A Christian Response to Radiometric Dating, by Tasman B. Walker - This reproduces Radiometric Dating: A Christian Perspective, by Dr. Roger C. Wiens, and gives a blow-by-blow rebuttal.
- K. F. Kuiper, A. Deino, F. J. Hilgen, W. Krijgsman, P. R. Renne, J. R. Wijbrans, Synchronizing Rock Clocks of Earth History, Science 25 April 2008: Vol. 320. no. 5875, pp. 500 - 504; DOI: 10.1126/science.1154339 - This is a research paper, so it is very technical. It is also very recent. There are several good illustrations. The correlation does not jump out and punch you in the eye, but reveals itself with careful study.
- Two Geologic Clocks Finally Keeping the Same Time, Richard A. Kerr, NEWS OF THE WEEK (25 April 2008), Science 320 (5875), 434. [DOI: 10.1126/science.320.5875.434] - The associated news story, less detailed, more accessible. Makes clear that the dating of the sediments is done via minerals in volcanic ash layers interspersed in the sediments. Also discusses the implication for the dating of the large extinction events, their association with volcanic eruptions, and the agreement between K-Ar dating fo the sediments and U-Pb dating of the lava flows. The adjustment of 0.65% makes dramatically clear how much explaining critics of radiometric dating have to do.
- Links to 13 articles that cite this one.
- "We avoid these drawbacks by applying the single-crystal 40Ar/39Ar dating method to sanidine phenocrysts extracted from numerous silicic tephra layers intercalated in an astronomically tuned open marine succession from the Messinian Melilla Basin in Morocco."
- earth-time.org has a series of pages providing brief and clear explanations of several aspects of ATS, Astronomical Time Scale
- Absolute astronomical time - Figure showing data. "Sapropels and/or carbonate cycles in the Mediterranean Narbone Formation and Trubi Marls were tuned to summer insolation 65° North with a 3-kyr lag between insolation maxima and sapropel (or low-carbonate grey-layer) midpoint."
- Floating astronomical time - Figure showing data. "Lower Cretaceous (Albian) deep-sea sediments (coccolith/globigerinacean marls) of the Umbria-Marche Apennines were drilled in 1979 near Piobbico, Italy. The drillcore revealed sustained, rhythmic sedimentary bedding, with drab facies representing normal stratified conditions, and red facies indicating downwelling warm saline waters. The drab facies is overprinted by cm- to dm-scale redox oscillations; these oscillations occur with a strong 5:1 bundling pattern."
- Earth's Orbital Parameters
- Orbitally Forced Insolation
- Precision and Accuracy of the ATS - "At the present time, models of Earth's orbital variations are reliably accurate over the past 50 Ma (Laskar et al., 2004). Prior to this time, expectations for chaotic behavior in the solar system casts uncertainty on the modeled orbits."
- Linda A. Hinnov and James G. Ogg, Cyclostratigraphy and the Astronomical Time Scale, stratigraphy, vol. 4, nos. 2/3, pp. 239-251, figures 1-2, 2007. - Another scientific paper (link provided by earth-time.org). Part of an issue on BEYOND THE GSSP: NEW DEVELOPMENTS IN CHRONOSTRATIGRAPHY, with a number of interesting titles. Note also the reletively recent date.
- "An important innovation in the International Geologic Time Scale 2004 is the use of astronomically forced stratigraphy, or cyclostratigraphy, to define geologic time over 0 to 23.03 Ma, much of it at an unprecedented resolution of 0.02 myr. In addition, ‘floating’ astronomical time scales with 0.10 to 0.40 myr resolution are defined for entire epochs and stages in the Paleogene and all three Mesozoic periods. Some of these calibrations use a new astronomical model with an hypothesized high accuracy over 0-250 Ma."
- "FIGURE 1: Astronomical forcing of the ancient sedimentary record."
- "The Cenozoic ATS is nearly complete. The scale is constructed from overlapping paleoclimate proxy records from the Mediter- ranean, Atlantic and Pacific basins, tied to the geomagnetic po- larity sequence and global biostratigraphic zones."
- New Astronomical Results Refine The Geological Time Scale, ScienceDaily (Nov. 3, 2004) - another news article. A bit older than the others. Talks more about the astronomical calculations.
These are about establishing a connection between astronomical cycles and radioactive dating. It is work from the past decade and now covers dates as early as 32 million years ago. If the radioactive decay rates were miraculously increased during the flood, then the development of orbital parameters must have been accelerated in just the same way.
University of Waikato radiocarbon dating sample record sheet
This section lists examples of radiometric dates which are inconsistent with known dates, inconsistent with each other, seriously inconsistent with the uniformitarian timescale, or inconsistent with other evidence.
Inconsistent with known dates
The five examples listed here are all cited in
The first one (Mt. St. Helens) is the subject of the article. The other five are quoted from
- Dalrymple, G.B., 40Ar/36Ar analyses of historic lava flows, Earth and Planetary Science Letters, 6:47–55, 1969.
In each case the K-Ar method is applied to a historical lava flow of known age less than 2200 years, and the radiometric age is calculated to be between a few hundred thousand and a few million years.
- Austin does indeed identify a real potential weakness in potassium-argon dating. However he is wrong that his phenocrysts constitute a fatal flaw in potassium-argon dating previously unknown to geology. In fact, the implications of phenocrysts were already well understood. Yes they are one of the variables, and yes, in some samples they do push the error bars. However, the errors they introduce are in the range of a standard deviation, they are not nearly adequate to explain errors as gross as three or more orders of magnitude, which would be necessary to explain the discrepancy between the measured age of rocks and the Biblical age of the Earth.
- What Austin did was to exploit a known caveat in radiometric dating; dramatically illustrate it with a high-profile test using the public's favorite volcano, Mount St. Helens; and sensationalize the results in a paper that introduces nothing new to geologists, but that impresses laypeople with its detailed scientific language.
- Only rarely does a creationist actually find an incorrect radiometric result (Austin 1996; Rugg and Austin 1998) that has not already been revealed and discussed in the scientific literature.
- Of the handful of flows that did contain excess 40Ar, only a few did so in significant amounts. The 122 BCE flow from Mt Etna, for example, gave an erroneous age of 0.25 0.08 Ma. Note, however, that even an error of 0.25 Ma would be insignificant in a 20 Ma flow with equivalent potassium content. Austin (1996) has documented excess 40Ar in the 1986 dacite flow from Mount St Helens, but the amounts are insufficient to produce significant errors in all but the youngest rocks.
- The 79 CE Mt Vesuvius flow, the dating of which is described above, also contained excess 40Ar. The 40Ar/39Ar isochron method used by the Berkeley scientists, however, does not require any assumptions about the composition of the argon trapped in the rock when it formed — it may be atmospheric or any other composition for that matter. Thus any potential error due to excess 40Ar was eliminated by the use of this technique, which was not available when the studies by Dalrymple (1969) and Krummenacher (1970) were done.
- Thus the large majority of historic lava flows that have been studied either give correct ages, as expected, or have quantities of excess radiogenic 40Ar that would be insignificant in all but the youngest rocks. The 40Ar/39Ar technique, which is now used instead of K-Ar methods for most studies, has the capability of automatically detecting, and in many instances correcting for, the presence of excess 40Ar, should it be present.
- (emphasis by Awc)
- Using science, there are at least three hypotheses that may be purposed to explain why Austin obtained 'dates' of 340,000 to 2.8 million years from his samples:
- Argon gas ('excess' argon) was incorporated into the glass and minerals in the dacite as they formed in the parent melt. The argon failed to degas from the minerals before the dacite solidified.
- Because all but one of the dates in the above table are below the 2 million year lower dating limit established by Geochron Laboratories, the dates may be nothing more than contamination artifacts from the mass spectrometer at Geochron Laboratories. The 2.8 million year old date also may have largely or entirely resulted from contamination.
- IF the Geochron mass spectrometer was exceptionally clean on the day that Austin's samples were run (that is, IF hypothesis #2 is not a factor), the dates may be approximately accurate. Even if the absolute values of the dates are highly erroneous, the relative order of the fractions' dates from oldest to youngest may be roughly correct. That is, the various minerals (phenocrysts) in the dacite may have grown in the parent melt at different times and the entire crystallization process may have taken as much as a few million years. Additionally, somewhat older xenoliths (foreign rocks) and xenocrysts (foreign minerals, for example, Hyndman, 1985, p. 250) from the surrounding rocks may have been incorporated into the melt as it rose to the Earth's surface.
- Any or all of these hypotheses are possible. Austin strongly argues that steps were taken in his laboratory to protect the samples from contamination and that xenoliths (foreign rocks, hypothesis #3) were removed from the samples before analysis. He also claims that microscopes were used to scan for 'foreign particles' (xenocrysts?, hypothesis #3) in the samples. Of course, he and his assistants may have missed many of the xenocrysts if they were small.
- Austin clearly ignores the possibility of contamination in the mass spectrometer (hypothesis #2) and the possibility that the phenocrysts in his samples may be much older than the 1986 AD eruption (hypothesis #3). Austin simply assumes that the first explanation is correct and then he proceeds to use the 'presence' of 'excess argon' in his samples to question the reliability of all K-Ar dates on other rocks and minerals. This is the logical fallacy of composition (Copi and Cohen, 1994). The validity of either hypothesis #2 or #3 would provide additional evidence that Austin's application of the K-Ar method is flawed and that he has failed to prove that the K-Ar method is universally invalid.
- Clearly, basic crystal chemistry and physics dictates that zoned and other relatively large phenocrysts grew deep within the Earth and existed before the glass matrix that rapidly formed during the 1986 eruption. Nevertheless, it is clear from Austin's essay that he has failed to incorporate the obviously diverse ages of the phenocrysts and the volcanic glass into his explanation for the origin of the dacite.
- Mt. St. Helens
- In 1996 rocks from the 1980s eruption of Mt. St. Helens were dated with potassium-argon dating to be 340,000 to 2.8 million years old.
- Lava flows from eruptions in Hawaii in 1800/01 were dated with potassium-argon dating to 1.46 million to 1.6 million years old.
- Mt. Etna
- Basalt from a 122 B.C. eruption of Mt. Etna gave an age with potassium-argon dating of 250,000 years.
- Basalt from a 1792 eruption gave an age with potassium-argon dating of 350,000 years.
- Mt. Lassen (California)
- Plaglioglase formed on Mt. Lassen in 1915 dated with potassium-argon dating to 110,000 years old.
- Sunset Crater (Arizona)
- Basalt formed in 1064-65 dated to 250,000-270,000 years of age.
Inconsistent with each other
- Mexican quarry
A British team reported finding markings in a layer of volcanic ash in a Mexican quarry that they interpreted as human footprints. Their measurements on quartz crytals found in the ash using Optically Stimulated Luminescence (OSL) indicated an age of 39 +/- 9 thousand years, but subsequent measurements by a team from Berkeley using the Ar-Ar method yielded an age of 1.3 +/- 0.03 million years. OSL is a non-radioactive technology to determine the time since certain crystals were last exposed to sunlight or last heated above 400 degrees, and is typically applied to sediments thought to be 300 to 100,000 years. After further investigations of the markings, including statistical comparisons to other findings of human and hominid footprints, the claim that these markings were human footprints was withdrawn.
- Surely the dating game is not as fickle as that. Actually, the dating is a problem whether they are footprints or not.
- It is not as if the British team pulled a date out of the air. They engaged the best laboratories in Britain and Australia, and used multiple dating methods on a range of different samples.5,6 Check this:
- Radiocarbon dating using Accelerator Mass Spectrometer on mollusc shells and organic balls by the Oxford Radiocarbon Accelerator Unit.
- Electron Spin Resonance dating on a mammoth molar by the Australian National University.
- Optically Stimulated Luminescence dating on sediments and ash by Oxford University.
- Argon-Argon dating on ash and lava by Open University.
- Uranium Series dating on animal bones by Bristol University.
- Nor does the British team trust the Berkeley work. Silvia Gonzalez said that one possible reason for the large discrepancy in dating may be due to the mixed nature of the volcanic ash: ‘This ash has got a very particular mineralogy that is very difficult to date.’
- Traditionally footprints are preserved by taking casts in plaster or latex. Experiments showed that these techniques damaged the friable ash in which the prints are preserved.
- The application of this technology to the footprints of the Oldest American allows the fragile prints to be preserved for posterity as well as for study.
- (emphasis by Awc)
- The results derived from different dating methods indicate that the Valsequillo gravels from the Barranca Caulapan area range in age from the Late Pleistocene, around 40,000 years ago, to the early Holocene, around 9,000 years ago. It is important to note that the Barranca Caulapan sands and gravels analysed were taken from strata geologically younger than the Xalnene ash layer in which the footprints were preserved.
- The mammoth molar was dated at approximately 27,000 years old using ESR; while an organic ball in the gravels was dated at 25,000 years old using C14. These materials were transported and incorporated into the fluvial sequence of the Barranca Caulapan.
- However, the mollusc shells are in situ in the deposits and were dated between 27,000 and 39,000 years old using C14.
- Attempts were made to date the Xalnene ash using Argon-Argon dating but the amount of potassium present in the ash was too low for a reliable age determination.
- More successful was the Optically Stimulated Luminescence (OSL) method to date quartz crystals found in baked lake sediments incorporated into the ash (as xenoliths) and secured an age of around 40,000 years. The sample was taken from the working quarry, 200m south from where the footprints were found.
- (Comment by Awc: Most of the different measurements and methods employed were on the material above the footprints. This made sense since the researchers were primarily interested in establishing that the footprints were older than previous finds. Of two attempts made to date the ash itself, the one using Ar-Ar failed to produce a result. The other, using OSL, is sensitive to the last time the crystal was exposed to sunlight, but also to the last time it was heated above 400 degrees.)
- Using palaeomagnetic analysis—a technique that looks at the Earth's magnetic field during past geologic time—and a radioactive dating technique called argon-argon, the team concludes the ash is actually 1.3 million years old.
- After visiting the site, Renne believes the markings are not really human footprints at all, but rather impressions left by machines or animals that have passed through the quarry in recent times.
- "You have to remember this is a public area," Renne said in a telephone interview. "Vehicles drive across it, you can see tire tracks on the surface. There are cows and other animals grazing nearby."
- Gonzalez told LiveScience that she and her colleagues will reply to Renne's findings formally in a scientific paper, but said that one possible reason for the large discrepancy in dating may be due to the mixed nature of the volcanic ash.
- "There are very different particles in there," Gonzalez said. "This ash has got a very particular mineralogy that is very difficult to date."
- Renne et al used Argon-argon dating and paeleomagnetic data suggesting that the layer in which the footprints are preserved is 1.30 ± 0.03 million years old, rather than the 40 000 years suggested by González et al. Renne suggested the marks were pick marks from nearby mining operations. As a result of this, while the editor decided to publish the original paper with a postscript pointing others to Renne's paper, some coauthors of the Gonazalez paper decided to withdraw their names from the publication.
- Gonzalez initially felt that the footprint marks could be differentiated from old quarry marks. Argon-Argon dating may be contaminated by olivine including older argon. Xenocrysts and phenocrysts were removed in a later dating of the ash material by Mark et al. 2010, which confirmed Renne's proposed age for the Xalnene Tuff. A re-examination of whether the features were footprints was conducted by Morse et al. 2010. A comparison with other markings thought to be footprints was undertaken, from various species of humans and in varying substrates and ages.
- 1. ^ a b Darren F. Mark, Silvia González, David Huddart, Harald Böhnel (2010) Dating of the Valsequillo volcanic deposits: Resolution of an ongoing archaeological controversy in Central Mexico. Journal of Human Evolution vol. 58, pages 441-445.
- 2. ^ Silvia González, David Huddart, Matthew R. Bennett and Alberto González-Huesca (2006) Human footprints in Central Mexico older than 40,000 years. Quaternary Science Reviews vol. 25, pages 201-222.
- 3. ^ Paul R. Renne, Joshua M. Feinberg, Michael R. Waters, Joaquin Arroyo-Cabrales, Patricia Ochoa-Castillo, Mario Perez-Campa and Kim B. Knight (2005) Age of Mexican ash with alleged ‘footprints’. Nature vol. 438 (1 December 2005) pages E7-E8.
- 4. ^ James Rose (2006) Editorial Quaternary Science Reviews vol. 25 pages 199-200.
- 5. ^ http://www.abc.net.au/rn/scienceshow/stories/2006/1564746.htm
- 6. ^ Sarita Amy Morse, Matthew R. Bennett, Silvia Gonzalez, David Huddart (2010) Techniques for verifying human footprints: reappraisal of pre-Clovis footprints in Central Mexico Quaternary Science Reviews, Volume 29, Issues 19-20, September 2010, Pages 2571-2578. (abstract
- Using an objective statistically based methodology developed here, these controversial marks are re-examined and found to be of questionable origin, as they are inconsistent with a suite of other, known human and hominin prints. Consequently, we argue that they should be removed as evidence in the ongoing controversy surrounding the colonization of the Americas.
- Grand Canyon
The Cardenas basalt at the bottom of the Grand Canyon was dated by the Rubidium-Strontium method to 1,070 million years (McKee and Noble, 1976), whereas lava which flowed into the canyon after it was cut—and therefore should be much younger—was dated with the same method to 1,340 million years (Austin, 1992). Whole rock samples from (in the first case) six or (in the second case) four different different lava flows were analyzed, a technique which only gives the age of the flows if they occurred at nearly the same time fed by an isotopically well-mixed source. Otherwise, the age returned, if it is meaningful at all, is the time since the material was last mixed, which might have been deep in the mantle. A more extensive study of the upper lava flows, with 20 samples, was done by Leeman already in 1974. He found a significant (>95%) correlation between the Sr87/Sr86 and Rb/Sr ratios (equivalent to an isochron) only for the four samples which showed independent signs of contamination from crust material. Mixing of two reservoirs with different compositions is one of the ways a straight line can be produced in an isochron plot that has no relation to the age of the material. Whether this has actually occured can usually be determined by plotting the data is a different way.
- It is a different story when the same rubidium-strontium method is used to date lava from volcanoes on the north rim of the Grand Canyon. We know these volcanoes are some of the youngest rocks in the canyon, because they spilled lava into the canyon after it had been eroded. Geologists generally think that these volcanoes erupted ‘only’ a million years or so ago. The measured age? 1.34 billion years.3
- 3. Austin, S.A. (ed.), Grand Canyon: Monument to Catastrophe, Institute for Creation Research, Santee, California, pp. 111–131, 1994. [book, not available online]
- During the last four years, the Institute for Creation Research has undertaken a research project to test the "ages" assigned by the best radioactive isotope dating methods to Grand Canyon rocks. This research has been called the "Grand Canyon Dating Project."
- One K-Ar "model age" determination gave 1.2 + 0.2 million years for the lava dam, 3 and geologists consider these lava flows to be Pleistocene in age.
- Figure 2 shows the isotope ratios of six rock samples from the Cardenas Basalt. These analyses were determined by E. H. McKee and D. C. Noble, two geologists working with support from the U.S. Geological Survey, National Science Foundation, and National Aeronautics and Space Administration. 5 The fact that the data seem to describe a line on the plot of 87Sr/86Sr versus 87Rb/86Sr, is thought to testify to the validity of the method and the suitability of the specimens, and thus the basalt was given an "age" interpretation by the two geologists. They reasoned that the Cardenas Basalt issued from a volcano or volcanoes which originally had lavas with a common ratio of strontium isotopes.
- Figure 3 shows the isotope ratios obtained for basaltic lava flows from the western Grand Canyon. The isotope ratios are from hawaiite lava flows from the Uinkaret Plateau on the north rim of Grand Canyon. Four whole rock samples and one feldspar sample separated from one of the whole rock samples were submitted independently to three different laboratories for testing. These data were obtained by the author, of the Institute for Creation Research, with private-donor support and the assistance of the three analytical laboratories.
- It would appear that an "age" relationship is suggested by the linear plot of Figure 3. Indeed, the same equation used to date the Cardenas Basalt at 1.07 billion years gives an "age" of 1.34 ± 0.04 billion years for these recent lava flows of western Grand Canyon.
- EDWIN H. McKEE and DONALD C. NOBLE. Age of the Cardenas Lavas, Grand Canyon, Arizona. GSA Bulletin; August 1976; v. 87; no. 8; p. 1188-1190. (abstract)
- Six whole-rock specimens of basalt from the Cardenas Lavas of the younger Precambrian Unkar Group yield a Rb-Sr isochron of 1.09 ± 0.07 b.y. This age is believed to approximate the time of extrusion of the lava. Potassium-argon age determinations of the lava are considerably younger and may reflect either diffusive loss of 40Ar or a period of heating about 800 m.y. ago.
- In other words, Austin claims that he has produced a seemingly reliable isochron age which must necessarily be wrong, and therefore the Rb-Sr isochron dating method, which is considered to be among the more reliable of radiometric dating methods, must be considered suspect.
- In order to understand what is going on, it is useful to examine the paper trail. Prior to ICR starting the Grand Canyon Dating Project, Austin (1988) produced a similar isochron -- this time 1.5 billion years -- for the same lava flows. He used data taken out of a mainstream scientist's paper (Leeman 1975) to construct the plot.
- Leeman's paper contains quite a bit more data than Austin used, with sufficient scatter to suggest that the resulting isochron probably is either an "inherited" reflection of the mantle source age or has no significance at all. However, Austin narrowed down the data set to flows which fell into a particular stratigraphic range -- "stages III and IV of Hamblin's later classification," said Austin (1988) -- and those selected data points fell quite close to a single line.
- In his 1988 paper, Austin noted that this sort of "false isochron" is well known, and explained in the mainstream literature. He cited a discussion of it in Faure (1986, pp. 145-147), a popular textbook/handbook on isotope dating methods.
- That is why isochron results are usually considered reliable if the data points are derived from the individual minerals of a single igneous rock sample, or on multiple samples of a single lava flow. The molten state allows isotopic homogenization, the solidification ceases that process, and therefore the expected result is the time since the solidification occurred.
- It is possible for the data points to fall on an isochron line if this requirement is violated. The result will still have the same meaning: the time since all of the samples were isotopically homogenized with respect to each other. However, that result does not have to be the time since each sample formed. Often it will be the isotopic age of the common source of the samples. That result could also be the age of the samples themselves, but only in the case where their common source was isotopically homogeneous -- i.e., zero-age -- when the samples formed from it.
- [emphasis in original]
- Before the Grand Canyon Dating Project began, in his 1988 Impact article, Austin admitted in print that the selected lava flows fell into two different stratigraphic stages. That is, the very information which he used to select the flows, also clearly indicates that they did not all occur at the same time. In his subsequent book (1994, p. 125), Austin indicated that his five data points came from four different lava flows plus an extracted "phenocryst" (large mineral which likely formed in the magma chamber and was not molten in the lava flow). We had known from the Impact articles that Austin's samples were not all cogenetic; years later we found out by his own admission that no two of them are so.
- In fact, as discussed above, the selection of non-cogenetic samples is sometimes used intentionally by isotope geologists. It is known to be a way to have an isochron dating method "look back" beyond a recent event to an earlier event -- the age of the common source of the samples. Thus, it is misleading for Austin to pretend that his resulting isochron plot should be expected to represent the age of the flows themselves.
- A geologist in my acquaintance suggested that this FAQ should be very short:
- It should merely state that Austin has confirmed what mainstream geologists have known all along: that the lithospheric mantle underlying the Grand Canyon must be older than the Cardenas Basalt.
- The mantle is the source of much of the sampled flows' material, and Austin's sampling technique matches the technique one would use to obtain a minimum for the age of the flows' source.
- W. P. LEEMAN. Late Cenozoic Alkali-Rich Basalt from the Western Grand Canyon Area, Utah and Arizona: Isotopic Composition of Strontium. Bulletin of the Geological Society of America, v. 85 no. 11 p. 1691-1696 (1974). (abstract)
- Twenty samples of Pliocene-Holocene basanite, hawaiite, and quartz-bearing basaltic andesite from the western Grand Canyon district have Sr87/Sr86 ratios that range from 0.7028 to 0.7069. Sixteen of these are lava flows that have Sr87/Sr86 (0.7028 to 0.7041), K/Rb (500 to 790), and Rb/Sr (0.016 to 0.047) ratios, which suggest a probable mantle origin. These data are typical of many late Cenozoic basaltic flows from the southern Great Basin and southern Colorado Plateau. In the remaining four Grand Canyon samples (3 hawaiites, 1 basaltic andesite) Sr87/Sr86, K/Rb, and Sr concentrations are suggestive of possible crustal contamination. Correlation coefficients for chemical and isotopic compositions of the Grand Canyon basalt are significant at the 95 percent level for covariances between Sr87/Sr86 and only TiO2, Rb/Sr, and Sr. The latter two correlations are mainly influenced by data for the four possibly contaminated basalt samples and are insignificant when those samples are omitted.
- The isotopic and chemical data are compatible with the model proposed by Best and Brimhall (1974) in which the Grand Canyon basalt flows are derived by variable degrees of partial melting of mantle material over a range in depth and modified by polybaric crystal fractionation during ascent to the surface. Small variations in isotopic composition in the bulk of these samples probably reflect heterogeneities in their mantle source regions rather than the effects of crustal contamination. It is inferred that the mantle underlying the western Grand Canyon district is similar in its isotopic characteristics to typical oceanic-type mantle regions.
- [emphasis by Awc]
- Mungo Man
In 1969 over 175 bone fragments were found on the edge of dry Lake Mungo in New South Wales. They were the remains of a woman, and were carbon dated to between 24,500 and 26,500 years old. Five years later more remains, this time of a man, were found 300 metres away. It has not been possible to use carbon dating on these remains, but the initial publication by their discoverer, Jim Bowler, and Alan Thorne estimated the age to be 28,000 to 32,000 years on the basis of geomorphological criteria and stratigraphic association with the previous find. In 1999 Thorne argued for an age of 62,000 ± 6,000 years based on new results using three different techniques (uranium series, electron spin resonance, and optically stimulated luminescence). That study was criticized in the professional literature on a variety of grounds. In 2003 Bowler presented a review of the dating attempts, including OSL data from 25 new samples. His conclusion was an age of 40 ± 2 kyr for both finds, which seems to have become a durable concensus.
This story provides a case study of the difficulties and limitations of dating human remains, especially near the “event horizon”, which is now about 50,000 years with the best available technology. In retrospect, some of the controversy arose because various effects (like contamination of the bones with recent carbon) added systematic error to the dating results, and some arose because the age of related objects (like the layer of sand in which the body was buried) could not be directly transfered to the find itself. The intensity of the controversy was doubtless fueled by the significance the older date would have on the field of human origins, particularly in relation to the theory that had been proposed by Thorne. The ages proposed at various times differed by up to a factor of two, compared to the ±5% error estimate of the current consensus. The extreme value propagated by Thorne was in the end about three of his error bars removed from the value later accepted.
Dating around Mungo 3
|Bowler and Thorne
||geomorphological criteria and stratigraphic association with Mungo 1
||28,000 to 32,000
||Grün and Schwartz
||ESR should not be applied to bone
|Thorne et al.
||62,000 ± 6,000
(during or before oxygen isotope stage 4, i.e. 57,000-71,000)
|"The bottom of the Mungo Unit from which LM3 was recovered has been securely dated to 43,000 years. Given that the grave of LM3 must have been dug from a higher, and therefore younger, land surface there is little possibility that the LM3 burial can be older than 43,000 years."|
Bowler et al. 2003: The OSL samples used to date LM3 by Thorne et al (1999) had little, if any, stratigraphic relationship with the original burial.
||calcite crust covering the skeleton
||sediment surrounding the skeleton
||25 new samples
||42,000 to 45,000
(or < 50,000)
- MacDonald, Janine, "Mungo Man older than thought", The Age, 21 May 1999, reproduced by Hitchcock.
- "Dawn in our Garden of Eden", Sydney Morning Herald, 22 February 2003, reproduced by Hitchcock.
- Lake Mungo 3 (No bibliographic information is given, but the domain is from the University of New England, Armidale NSW 2351 Australia)
- The Lake Mungo 3 skeleton was discovered by Jim Bowler. In February 1974, after prolonged rain in 1973, Bowler noticed the exposed left side of a carbonate encrusted human cranium 500m east of the Mungo 1 cremation site. Later that month the extended burial that was Lake Mungo 3 was excavated by a team from the Australian National University (Bowler and Thorne 1976). When first published this burial had not been directly dated but Bowler and Thorne argued on the basis of geomorphological criteria and stratigraphic association with Mungo 1 that an age of 28,000 to 32,000 years BP was probable (1976: 136-138). In 1987 Caddie et al. reported an electron spin resonance date on bone of 31,000 ±7000 years BP for Lake Mungo 3. Grün and Schwartz (1987) argue that while ESR can produce reliable dates on dental enamel bone is not a suitable material for ESR. Most recently Thorne et al. (1999) report that the age of the Lake Mungo 3 burial, as determined by the combined results of electron spin resonance (ESR) on dental enamel, U-series on calcite crust covering the skeleton and OSL on the sediment surrounding the skeleton indicate colonisation during or before oxygen isotope stage 4 (57,000-71,000). These dates make little sense given the original stratigraphic argument and the absence of archaeological materials of similar age from the Willandra Lakes region. The bottom of the Mungo Unit from which LM3 was recovered has been securely dated to 43,000 years. Given that the grave of LM3 must have been dug from a higher, and therefore younger, land surface there is little possibility that the LM3 burial can be older than 43,000 years. Critiques of Thorne et al. (1999) dating of LM3 by Gillespie and Roberts (2000), and Bowler and Magee (2000), have been published in the Journal of Human Evolution. In the same volume Brown (click for pdf copy) examines Thorne et al. (1999) claims for morphological gracility and male sex for LM3. There is a rep[l]y to the two dating critiques by Grün et al. (2000). A review of the debate can be found in Brown (2000b, click for a pdf copy), with further contributions by Thorne and Curnoe (2000) and Brown and Gillespie(2000). Bowler et al. (2003, click for a pdf copy) argue that the OSL samples used to date LM3 by Thorne et al (1999) had little, if any, stratigraphic relationship with the original burial. They report the results of 25 new OSL dates which suggest LM3 can not be older than 50,000 years BP. While the dating of the Lake Mungo stratigraphic sequence now seems more secure I don't believe that Bowler et al (2003) have established a minimum age for the burial, only a possible maximum. When LM3 was discovered it had been exposed by erosion. You can only speculate at the nature of the original deposit above the burial, and the land surface from which it was intered. I suspect that LM3 was buried during a period in which the nearby lake was full of water, with the environment most suited for human habitation, but lake levels fluctuated over a a long period of time (Bowler et al. 2003). A range of 15,000 to 50,000 appears possible (Gillespie 2002, click for pdf copy).
- ABSTRACT. The dating of selected archaeological and megafaunal sites from the Australian region is reviewed, with emphasis on recent work at some of the oldest sites. Improved chemical procedures with decreased analytical background for 14C analysis, combined with new luminescence dating methods, has confirmed many of the results processed decades ago and significantly increased the maximum age for some others. The oldest occupation horizons in four different regions reliably dated by defendable multi-method results are in the range 42–48,000 calendar years ago, overlapping with the age range for similarly well-dated undisturbed sites containing the youngest extinct megafauna. There is less secure evidence suggesting some archaeology may be earlier and some megafauna may have survived later than this period.
- Traditional 14C dating using radiometric counting has become less important in Sahul, as elsewhere, since accelerator mass spectrometry (AMS) laboratories began to take on large workloads from the mid 1980s. In many situations this new measurement technology also allowed better pretreatment chemistry to be applied in the isolation and decontamination of specific sample components. At about the same time newer thermoluminescence (TL), optically stimulated luminescence (OSL), electron spin resonance (ESR), amino acid racemization (AAR), and uranium-thorium series (U/Th) dating methods began to make significant contributions to archaeology and the earth sciences.
- Ongoing new work suggests that the Upper Mungo occupation horizons are close to 44 ka (Spooner et al. forthcoming).
- Burial Mungo 1 (or WLH-1), yielded dates of 28 ka on an acid insoluble residue and 22 ka on “apa- tite” (Bowler et al. 1972). Later work showed that >90% of the carbon in this burnt bone was alkali- soluble humic acids dated at 29 ka, with an A/B/A insoluble residue at 20 ka.
- No 14C dates have been reported for the Mungo 3 skeleton, nor on any archaeological material associated with the burial, and the response of Grün et al. (2000) has not resolved all the issues.
- Chappell et al. (1996a) pointed out that such distributions are simply reflecting the limitations of 14C dating, includ- ing contributions from chemical decontamination, analytical background and calibration. The fact that older 14C dates exist for geological samples is irrelevant because sufficient carbon in uncontam- inated form is rare in the oldest archaeological sites. Over the three decades of 14C dating results from Europe and Australia shown in Figure 4A, chemistry has improved and analytical background reduced from about 1% to 0.1%, resulting in a change of the applicable “event horizon” from about 40 ka to 50 ka. Similar technological advances have also been made in other dating methods, but incorrect dates have not been removed from the distributions.
- Many black samples labeled “charcoal” from Australian archaeological sites turn out to contain almost no real charcoal; all fractions have similar carbon content and might more descriptively be labeled unburnt detritus or “compost” (Gillespie 1998).
- Thus both charcoal and carbonate samples are subject to contamination and often give incorrect results in the >30,000 BP period, even when the dates are clearly resolved from the “event horizon”. Removing the dubious organics, shell, otolith and eggshell dates from the Australian dataset in Fig- ures 2 and 4A leaves the charcoal results shown in Figure 4B as the most reliable 14C evidence for human occupation. These 44 “good” charcoals are all finite age estimates younger than 50 ka and well supported by some combination of TL, OSL, U/Th, and ESR dating.
- The direct 14C dating of bone has had a troubled history, in most cases because the samples fail to meet one of the original assumptions for the method: “the possibility of obtaining unaltered sam- ples” (Arnold and Libby 1949). Poor organic preservation in most Willandra human bones is similar to bones from other semi-arid open sites in Australia or elsewhere. Well-documented methods for reliable 14C measurements on single amino acids from bone collagen (e.g. Stafford et al. 1991) have not been applicable because almost no protein has been found. Phase 1 or 2 chemistry has so far pro- duced no results older than about 28 ka for the Mungo 1 cremation, with a younger group of burials at 13–14 ka near Lake Garnpung (WLH-23, 24 and 122; Gillespie 1997).
- Dating the first Australians has become an issue for which 14C may no longer be the final word, because we are near a reliable age limit for the method. The “event horizon” with best available tech- nology is about 50 ka, with realistically large error ranges reflecting uncertainty in both measure- ment and calibration of 14C dates. Other dating methods such as OSL, ESR, AAR, and U/Th extend the available age range, sometimes by an order of magnitude, and there is increasingly good agree- ment between methods within the 14C limits. Direct bone dating remains a difficult problem throughout the Late Pleistocene, and significant technical developments have been required in all dating techniques to push back the time of first human occupation from the very uncertain >37,800 BP of thirty years ago.
- Australia’s oldest human remains, found at Lake Mungo, include the world’s oldest ritual ochre burial (Mungo III)1 and the first recorded cremation (Mungo I)2. Until now, the importance of these finds has been constrained by limited chronologies and palaeoenvironmental information3. Mungo III, the source of the world’s oldest human mitochondrial DNA4, has been variously estimated at 30 thousand years (kyr) old1, 42–45 kyr old5,6 and 62 ± 6 kyr old7,8, while radiocarbon estimates placed the Mungo I cremation near 20–26 kyr ago2,9,10. Here we report a new series of 25 optical ages showing that both burials occurred at 40 ± 2 kyr ago and that humans were present at Lake Mungo by 50–46 kyr ago, synchronously with, or soon after, initial occupation of northern11,12 and western Australia13. Stratigraphic evidence indicates fluctuations between lake-full and drier conditions from 50 to 40kyr ago, simultaneously with increased dust deposition, human arrival and continent-wide extinction of the megafauna14,15. This was followed by sustained aridity between 40 and 30 kyr ago. This new chronology corrects previous estimates for human burials at this important site and provides a new picture of Homo sapiens adapting to deteriorating climate in the world’s driest inhabited continent.
- The importance of Lake Mungo to world archaeology and human evolution has recently been accentuated by claims for direct dating of the Mungo III skeleton to 62 ± 6 kyr ago8 and for the extraction of mitochondrial DNA from these remains4. The Mungo I and III burials were both inserted near the Lower to Upper Mungo strati- graphic boundary. Mungo III was placed in a grave 80–100 cm deep, and traces of pelletal clay and dark, reworked soil were found in the grave fill. The grave was dug into sands, dated here to 42 ± 3 kyr ago, underlain by a thin band of pelletal clay derived from the lake floor (Fig. 2). The overlying unit sealing the grave is dated to 38 ± 2 kyr ago. Therefore, Mungo III was buried 40 ± 2 kyr ago, close to the age estimates from two previous studies5,6, but 20 kyr later than the most recent claims7,8.
- Reasons for the 20-kyr age discrepancy invite speculation. One factor may involve uncertainties in U-migration29, which is enhanced in carbonate-rich sedimentary deposits such as those studied here. U-migration can considerably affect the accuracy of ‘open system’ ESR and U-series ages, such as those used to date the Mungo III skeletal remains7,8. The previous two optical ages for the Mungo III burial relate to sediments collected in uncertain strati- graphic contexts more than 300 m away from the burial site8.
- The Mungo I cremation is indistinguishable in age from the Mungo III burial. Our new age constraints for Mungo I are 15– 20 kyr older than the previous radiocarbon-based estimates2,9,10, a difference we attribute to contamination of the radiocarbon samples by younger carbon.
- Our study shows that humans were present at Lake Mungo as early as 50–46 kyr ago. We find no evidence to support claims for human occupation or burials near 60 kyr ago. A most significant climatic change of the last 60 kyr occurred near 40 kyr ago, when early lake-shore Homo sapiens, with culturally advanced mortuary practices, were forced to adapt to increasing aridity. The Lake Mungo evidence presented here provides a new chronological and environmental context for examining the interaction between the first human arrivals, the last of the megafauna, and the Australian landscape under conditions of major climatic change.
- Java Man
The homo erectus fossils from Indonesia were dated in 1996 at 30,000 to 50,000 years of age, using analysis of radioactive elements in fossil-bearing sediment. However, new dates published in 2010 based on argon decay in rocks above and below the fossils gave their age as about 550,000 years.
- It all depends which radiometric method you use to assess the fossils’ age, New York University anthropologist Susan Antón reported at the annual meeting of the American Association of Physical Anthropologists.
Inconsistent with the uniformitarian timescale
- Hawkesbury Sandstone
- An item that appeared to be petrified wood was found by a local resident in a crack in a block of Hawkesbury Sandstone, believed by conventional geologists to be 225–230 million years old. He turned the sample over to creationist Andrew Snelling, who submitted it to Geochron Labs for carbon-14 analysis, which, when interpreted as an age, returned 33,720±430 years. The head of the Radiocarbon Group at Geochron Labs has expressed doubt that the sample was wood at all. 33,700 years is 5.9 times the half-life of carbon-14, and 25.9 is 60, so contamination with modern carbon at the 2% level would be sufficient to give this result. Contamination could occur, for example, through percolation of rainwater while the sample was still buried or through less than meticulous handling during sample collection.
- In June 1997 a large finger-sized piece of fossil wood was discovered in a Hawkesbury Sandstone slab just cut from the quarry face at Bundanoon (see photo, right).8 Though reddish-brown and hardened by petrifaction, the original character of the wood was still evident.
- Because this fossil wood now appears impregnated with silica and hematite, it was uncertain whether any original organic carbon remained, especially since it is supposed to be 225–230 million years old.
- The analytical report from the laboratory indicated detectable radiocarbon had been found in the fossil wood, yielding a supposed 14C ‘age’ of 33,720 ± 430 years BP (before present). This result had been ‘13C corrected’ by the lab staff, after they had obtained a d13CPDB value of –24.0‰.9 This value is consistent with the analyzed carbon in the fossil wood representing organic carbon from the original wood, and not from any contamination.
- Anticipating objections that the minute quantity of detected radiocarbon in this fossil wood might still be due to contamination, the question of contamination by recent microbial and fungal activity, long after the wood was buried, was raised with the staff at this, and another, radiocarbon laboratory. Both labs unhesitatingly replied that there would be no such contamination problem. Modern fungi or bacteria derive their carbon from the organic material they live on and don’t get it from the atmosphere, so they have the same ‘age’ as their host. Furthermore, the lab procedure followed (as already outlined) would remove the cellular tissues and any waste products from either fungi or bacteria.
- Index to Creationist Claims, edited by Mark Isaak, Copyright 2008. Claim CD011.5
- 1. It is doubtful that the sample was even wood. Snelling was not even sure what the sample was. Nor could the staff at Geochron tell what the sample was (Walker 2000). It may not even have retained any of its original carbon. Using carbon dating was pointless from the start since it would inevitably give meaningless results.
- 2. The sample was porous, making it likely that it would have absorbed organic carbon from the groundwater. It was probably this contaminating carbon that produced the date. Another possibility is that some 14C was created in situ by natural radioactivity in the surrounding rocks (Hunt 2002).
- 3. Furthermore, 33,720 years is still significantly older than the age which many creationists, Snelling included, ascribe to the earth, and there are no plausible sources of error to make the age younger than 33,000 years.
- According to uniformitarian geology the rock this wood was found in has been above the water table for millions of years, so this can be eliminated as a possible source of contamination. This was explained in one of Talk.Origins references (Dating dilemma deepens: Moore on ancient radiocarbon), yet the Talk.Origins author apparently chose to ignore it. [Link is dead. --Awc]
- Snelling has not submitted this article for peer-review, nor does he apparently have any intention of doing so. The paper is for dissemination to other young-earth creationists. As you read, please note that the principle question regarding these studies is the level of contamination in the samples. Snelling NEVER addresses the fundamental objection. [emphasis in original]
- [Quoting an email from Dr. Alexander Cherkinsky, head of Geochron Labs Radiocarbon group]
- I remember this sample very well. So they called it "wood'? It wasn't wood at all and more looked like the iron concretion with the structures lightly similar to wood. I have told about that to submitter, but anyway they wanted to date the sample. I think maybe this concretion was formed significantly later than Triassic period and I do not think that is a very rare case when you can find younger formation in the old deposits especially if it is sand or sandstones which could be easy infiltrated with oil solutions.
- Please note, Snelling seems puzzled that an iron concretion could give a radiocarbon age. This is not at all uncommon and a cursory look at the literature would have given Snelling something to think about when he noticed the iron present in the sample.
- Furthermore, it is this microbial contamination that is responsible for the 'apparent age' of the sample. We have Snelling admitting that the sample was altered (silica and iron-rich), the radiocarbon lab manager-- whose specialty is C-14 dating of woody material-- stating that the sample appears to be a concretion and a study that shows quite clearly how such samples can give 'dates' through contamination. Unfortunately, Snelling keeps the data locked in a drawer and refuses to submit it for peer-review. Until he does so, recent contamination of the sample remains the most viable explanation for the supposed 'anomalous' dates. Note, this is not a case of he said, she said. This is a case of poorly documented science on the part of Snelling. He wants to overturn all of geology, but does not want to properly document the evidence.
- It is also very likely that Snelling repeated this error half a world away. In his 'study' of the Marlstone rock bed in England, he also reports anomalous C-14 ages in an area known to contain younger iron oxidative products.
- [The following is in relation to the Marlstone case.]
- Snelling lists 4 reasons why contamination can be ruled out. He states:
- (1) since labs all obtained similar ages this rules out contamination.
- That is simply twisted logic. If the contamination is all of a similar age, then the data will be similar.
- (2) he talks about levels of 'unavoidable contamination'
- This seems to cancel the logic in point number 1, he also 'invents a 0.2% value out of thin air, contamination could be more and he needs to document that HIS samples contain no more than 0.2% of contaminants. Cherkinsky noted (in a personal communication) that iron deposite contain up to 15% organic matter. Furthermore, if the sample is indeed a Jurassic wood any contamination would be a problem.
- (3) He states the the d13C values are indicative of organic plant material.
- This is correct but as noted above contamination by younger organic plant material will still result in 'characteristic d13C values.
- (4) Snelling asserts that if anyone claims contamination it would be an ad-hominem attack against respected laboratories.
- One wonders why Snelling might mention this since he claims (kind of) that the samples are not contaminated. Perhaps, it is a pre-emptive strike since he realized that he has not fully documented his case for no contamination? Unfortunately, contamination can occur at any point along the way including during formation of the sample. As noted above and again below, there are cases where contamination cannot be removed. Hence, not a single one of his 4 reasons involves unequivocal proof that his samples were not contaminated! It is also not a slam on the laboratories.
- Snelling does not demonstrate that the fossil wood was 'impregnated during fossilisation' nor does he demonstrate that this 'wood' is in-situ. Limonite will also 'splinter'.
- Note: These data would be absolutely required by peer-reviewed journals in light of the known complications of C-14 dating in iron-rich deposits so I am asking the same thing any good editor would ask.
- SNELLING ANSWERS (SORT OF)
- AS: Snelling?
- JM: Meert
- JM: The Hawkesbury sandstone is highly jointed (BMR Report The Sydney Basin) which allows fluid flow and rootlet and other microbial material penetrate the sandstone.
- JM: Partly true, because no one disputes the fact that wood can be dated. The problem is that the type of replacement suggested by BOTH Snelling and Cherkinsky allows contamination of the sample. If the original wood is older than ~50K years, there would be no original carbon in the wood and the lab would be measuring only the contamination. This is a critical point NEVER addressed by Snelling with the proper analysis.
- AS: That was the rationale behind submitting this sample to Geochron's radiocarbon laboratory. Its validity as fossilised wood was carefully checked and was never in doubt.
- JM: Actually, it is very much in doubt as the letter from Dr. Cherkinsky attests. Snelling has provided hearsay evidence to support his claim and he could rightly claim Cherkinsky's statement is hearsay. At this point both are irrelevant. It might be righteous indignation, but as any scientist worth his/her salt knows---the case rests on the evidence. Snelling can settle this by providing the SEM photos (Scanning Electron Microscopy) and the chemical analyses of the sample. I assume, as a careful scientist, he ran these critical tests.
- AS: The question was whether Geochron would find any residual organic material in the sample, and therefore be able to obtain a radiocarbon analysis. Thus their lab report answered our questions.
- JM: Actually it did no such thing. The lab reported an age. Snelling would have had to do the contamination analysis himself.
- AS: Third, the question of contamination is dealt with in the lab report by the chemical treatment of the sample in its preparation for analysis.
- JM: Actually, this is very much in doubt as the paper by Bird et al. (1994) indicates. The procedure followed in that study shows that the cleaning methods do not remove all contaminants in these iron nodules: The procedure for AMS C-14 sample prep is described by Bird et al. (1994) is lengthy (compare to Snellings): Here is the summary:
- The sample still gave C-14 ages due to microbial contamination that was not removed by this procedure. Compare to what Snelling reports.
- JM: The lab report from Geochron is not at issue here. Nor is the 'age'---for what it is worth, I do believe that Geochron returned the age to Snelling as documented. The issues are the significance of the age and the possibility of contamination. Snelling has not answered those questions.
- Final Note: If Snelling can indeed substantiate his case, I will publicly apologize and withdraw this material. Most scientists, when criticized respond by thoroughly documenting their case.
- JM: ... However, let's assume, for the sake of argument that 10-15% of ages produced are anomalous. That leaves 85% of age determinations that are not. How do you explain the 85% of ages that are not anomalous? ... I went back and looked at the percentage of age determinations that I personally have worked on and less than 5% are troubling. Each one of those 5% have a reasonable explanation for why they didn't work (from excess argon clearly evident in the plateaus to severe hydrothermal alteration of the samples).
- HF: I retracted, with apologies, the statement that MOST dates were thrown out and admitted I had understood or been told wrongly about this.
- JM: Your intuition may be correct that most geochronologic data available are K-Ar determinations. I would not bet against that conclusion, since it was one of the first and cheapest methods for determining ages. It also has a wide range of applications so the cheapness and the range made it extremely popular. It still is used quite a bit today and it does quite a good job. Today, our understanding of closure temperatures and the behavior of the K-Ar system is much better constrained by using the 40Ar/39Ar method. In general, most of the K-Ar ages that I have personally examined are quite robust. In the cases where the ages seemed a bit askew based on more recent datings, the 40Ar/39Ar system usually reveals the reason why the K-Ar ages were skewed. In fact, the 40Ar/39Ar has been a nice addition and way to double check for isotopic disturbances in the K-Ar system.
- JM: The best part about the whole process is that we can now tell, with some ease and care, when isotopic systems have been disturbed. In fact, some of these thermal disturbances have helped us decipher tectonic histories with greater precision than ever (see Meert, 2002 available at http://www.clas.ufl.edu/users/jmeert).
- Granting that the specimen is fossilized wood, then where did it fossilize? Certainly not while buried in sandstone well above the water table. Fossilization requires the presence of circulating groundwater which bring in the dissolved minerals that slowly replace the organic materials of the original wood. So the fossilization must have occurred somewhere else before its entombment in the sandstone.
- The sample received by Geochron is described by Dick Reesman as soft and fluffy(?) and very small. It didn't seem to be wood and he couldn't tell if it ever had been wood. It was largely non-combustible (mineral?) But some carbonaceous material that had not been removed by the cleanup (you can't get rid of everything, especially when you don't know what it is that you want to keep) produced a radiocarbon age value of about 34,000 years.
- But there is no evidence to show that this material was the original wood and thus no assurance, apart from that of Dr Snelling (hardly a disinterested observer), that this "age" bears any relation to reality.
- How effective was the sample clean up really? The hot acid and alkali washes would remove the carbonates and organic contaminants, but what about materials such as carbon(2)(3)? This could be carried in by groundwater and would not have been affected by the washes. In the ref.(2), colloidal carbon in groundwaters is discussed as a possible contaminant and it is claimed that a 1% contamination of 'infinitely old' carbon with modern carbon would yield an apparent age of only 38,000 years. Ref.(3) mentions contamination from groundwaters by carbon exchange.
- Gunther Wagner (4) discusses a number of contamination possibilities and concludes that
- "....the applicability of C14 dating toward high ages is limited by unavoidable contamination rather than by instrumental capabilities..."
- In the paper it is assumed that all contamination has been removed by the washes while, in the 'feedback', other contamination is declared to have been impossible, according to some un-named 'authorities'.
- Obviously, sample contamination is a key question here and Dr. Snelling has shown us no good reason to conclude that what was 'dated' here was anything else but organic contamination of a long-mineralized fossil.
- Take a look at the photograph of the sample; note that it is stuck in a crack in the stone. Would not Dr. Snelling's hugely overblown scenario of the fossil being "Buried catastrophically in the sand by the raging Flood waters....." require at least that the fossil end up completely encased in sandstone? It looks to me as if the fossil arrived at its resting place after the sand had turned to sandstone rather than before.
- But he has broken a cardinal rule of sampling for radiocarbon dating:
- "Second, great care must be taken in collecting and packing samples to avoid contamination by more recent carbon.......Also, the stratigraphy should be carefully examined to determine that a carbon sample location was not contaminated by carbon from a later or an earlier period."
- Quoted from: Chronological Methods 8: Radiocarbon Dating A University of California in Santa Barbara course.
- JM = Jim Moore, TW = Tas Walker, DR = Dick Reesman (a Geochron official)
- DR: Had this sample been submitted by one of our clients other than a Creationist we would have said it was not worth analyzing since no one knew what it was, and what good is a "date" on some unidentified material if it can’t be related to anything specific in the real world? Remember, I said before that we will more readily analyze bad samples for Creationists than for anyone else? After all, they can have us analyze whatever they want. And what do you think they would say if we declined to carbon date a “225–230 million piece of ‘wood’”? My suspicion is they would most likely say “Conspiracy of silence!” or something similar.
- For example, samples of coal almost invariably have measurable 14C [Lowe, D.C., Problems associated with the use of coal as a source of 14C-free background material, Radiocarbon 31:117–120, 1989]. Note that the coal samples were analyzed to find a source devoid of 14C to use as a blank in the processing of samples for 14C dating—evolutionary scientists would not normally bother trying to measure 14C in stuff they think is millions of years old.
Inconsistent with other evidence
- Devils Postpile (California)
- Basalt from Devils Postpile dates with potassium-argon dating to 940,000 years ago, although stratigraphic study puts the rock as being less than 100,000 years old.
- Keramim (Israel)
- Basalt from Keramim dates with potassium-argon dating to 250,000 years ago, but has 'stone age' artefacts underneath it.
- Hornton Quarries (England)
- Limestone in the Marlstone Rock Bed at Hornton Quarries was dated by index ammonite fossils at about 189 million years old, but has embedded wood dated with carbon dating between 20,000 and 30,000 years old.
C-14 levels in ancient carbon
- Fossils older than 100,000 years should have too little 14C to measure, but dating labs consistently find 14C, well above background levels, in fossils supposedly many millions of years old.21,22 For example, no source of coal has been found that lacks 14C, yet this fossil fuel supposedly ranges up to hundreds of millions of years old. Fossils in rocks dated at 1–500 Ma by long-age radioisotope dating methods gave an average radiocarbon ‘age’ of about 50,000 years, much less than the limits of modern carbon dating22 (see pp. 65–69 for why even these radiocarbon ages are inflated). Furthermore, there was no pattern of younger to older in the carbon dates that correlated with the evolutionary/uniformitarian ‘ages’.
- Even Precambrian (‘older than 545 Ma’) graphite, which is not of organicorigin,contains14Cabovebackgroundlevels.22 Thisisconsistent with Earth itself being only thousands of years old, as a straightforward reading of the Bible would suggest.
- Jonathan Sarfati. Diamonds: a creationist’s best friend: Radiocarbon in diamonds: enemy of billions of years. First published: Creation 28(4):26–27. September 2006. - secondary source
- John R. Baumgardner, D. Russell Humphreys, Andrew A. Snelling, and Steven A. Austin. Measurable 14C in Fossilized Organic Materials: Confirming the Young Earth Creation-Flood Model. Presented at the Fifth International Conference on Creationism, Pittsburgh, Pennsylvania, August 4–9, 2003. Published in: Proceedings of the Fifth International Conference on Creationism, R.L. Ivey (Ed.), pp.127–142, 2003.
- Measuring notable levels of 14C in samples intended as procedural blanks or “background” samples is a phenomenon that has persisted from the earliest days of AMS down to the present time. For example, Vogel, Nelson, & Southon (1987) describe their thorough investigation of the potential sources and their various contributions to the 14C background in their AMS system. The material they used for the blank in their study was anthracite coal from a deep mine in Pennsylvania. An important part of their investigation was variation of the sample size of the blank by a factor of 2000, from 10 μg to 20 mg. They found that samples 500μg and larger displayed a 14C concentration of 0.44±0.13pmc, independent of sample size, implying this 14C was intrinsic to the anthracite material itself. For samples smaller than 500μg, the measured 14C could be explained in terms of this intrinsic 14C, plus contamination by a constant amount of modern carbon that seemed to be present regardless of sample size. After many careful experiments, the authors concluded that the main source of this latter contamination was atmospheric CO2 adsorbed within the porous Vicor glass used to encapsulate the coal sample in its combustion to CO2 at 900°C. Another source of smaller magnitude was CO2 and CO adsorbed on the walls of the graphitization apparatus retained from reduction of earlier samples. It was found that filling the apparatus with water vapor at low pressure and then evacuating the apparatus before the next graphitization mostly eliminated this memory effect. Relative to these two sources, measurements showed that storage and handling of the samples, contamination of the copper oxide used in combustion, and contamination of the iron oxide powder used in the graphitization were effectively negligible. And when the sample size was greater than 500μg, the intrinsic 14C in the coal swamped all the sources of real 14C contamination. Rather than deal with the issue of the nature of the 14C intrinsic to the anthracite itself, the authors merely refer to it as “contamination of the sample in situ”, “not [to be] discussed further.”
- The laboratory claims most of their quoted system background arises from sample processing. This processing involves combustion (or hydrolysis in the case of carbonate samples), acetylene synthesis, and graphitization. Yet careful and repeated analysis of their methods over more than 15 years have convinced them that very little contamination is associated with the combustion or hydrolysis procedures and almost none with their electrical dissociation graphitization process. By elimination they conclude that the acetylene synthesis must contribute almost all of the system background. But they can provide little tangible evidence it actually does.
- Other RATE projects are building a compelling case that episodes of accelerated nuclear decay must have accompanied the creation of the earth as well as the Genesis Flood (Baumgardner, 2000; Humphreys, Baumgardner, Austin, & Snelling, 2003; Snelling & Armitage, 2003). We believe several billions of years worth of cumulative decay at today’s rates must have occurred for isotopes such as 238U during the creation of the physical earth, and we now suspect a significant amount of such decay likely also occurred during the Flood cataclysm. An important issue then arises as to how an episode of accelerated decay during the Flood might have affected a short half-life isotope like 14C. The fact that significant amounts of 14C are measured routinely in fossil material from organisms alive before the cataclysm argues persuasively that only a modest amount of accelerated 14C decay occurred during the cataclysm itself. This suggests the possibility that the fraction of unstable atoms that decayed during the acceleration episode for all of the unstable isotopes might have been roughly the same. If the fraction were exactly the same, this would mean that the acceleration in years for each isotope was proportional to the isotope’s half-life. In this case, if 40K, for example, underwent 400Ma of decay during the Flood relative to a present half- life of 1250Ma, then 14C would have undergone (400/1250)*5730 years = 1,834 years of decay during the Flood. This amount of decay represents 1–2-(1834/5730)=20% reduction in 14C as a result of accelerated decay. This is well within the uncertainty of the level of 14C in the pre-Flood world so it has little impact on the larger issues discussed in this paper.
- The data already present in the peer-reviewed radiocarbon literature suggests there is indeed intrinsic 14C in such materials that cannot be attributed to contamination. If this conclusion proves robust, these reported 14C levels then place a hard limit on the age of the earth of less than 100,000 years, even when viewed from a uniformitarian perspective.
- Nadeau M-J, Grootes PM, Voelker A, Bruhn F, Oriwall A, 2001. Carbonate 14C background: Does it have multiple personalities? Radiocarbon 43 (2A), 169–176. (abstract)
- Measurements of the radiocarbon concentration of several carbonate background materials, either mineral (IAEA C1 Carrara marble and Icelandic double spar) or biogenic (foraminifera and molluscs), show that the apparent ages of diverse materials can be quite different. Using 0.07 pMC obtained from mineral samples as a processing blank, the results from foraminifera and mollusc background samples, varying from 0.12 to 0.58 pMC (54.0-41.4 ka), show a species-specific contamination that reproduces over several individual shells and foraminifera from several sediment cores. Different cleaning attempts have proven ineffective, and even stronger measures such as progressive hydrolization or leaching of the samples prior to routine preparation, did not give any indication of the source of the contamination. In light of these results, the use of mineral background material in the evaluation of the age of older unknown samples of biogenic carbonate (>30 ka) proves inadequate. The use of background samples of the same species and provenance as the unknown samples is essential, and if such material is unavailable, generic biogenic samples such as mixed foraminifera samples should be used. The description of our new modular carbonate sample preparation system is also introduced.
Correlations between radiometric dates and incremental dates
- "Radio isotope dating, using 210Pb (lead) (Crozaz & Langway, 1966), 32Si (silicon), 39Ar (argon) (Oeschger et al., 1977) and 14C (carbon) (Paterson et al., 1977) have all been used with varying degrees of success, over different time scales, to determine the age of ice cores."
- Oeschger, H., Stauffer, B., Bucher, P. & Loosli, H.H., 1977. Extraction of gases and dissolved and particulate matter from ice in deep boreholes. In: Isotopes and impurities in Snow and Ice, International Association of Scientifc Hydrology Publication No. 118. IASH, Washington D.C., pp. 307-311.
Variability with time
Helium Diffusion Age of Zircons
Helium Diffusion in Zircons — Does it show that the earth is young? - links to articles on both sides
- However, the most extensive and devastating recent criticisms of Dr. Humphreys' claims originate from old-Earth creationist and materials engineer Dr. Gary H. Loechelt. Dr. Loechelt applied multi-domain diffusion models to Dr Humphreys' and R. V. Gentry's data, which raise many new arguments that further undermine Dr. Humphreys' young-Earth creationist (YEC) claims. Loechelt (2008a; 2008b), which are at the old-Earth creationist Reasons to Believe website, are brief and less technical summaries of Loechelt (2008c). Loechelt (2008c) is a detailed report that argues that Dr. Humphreys' claims and his underlying assumptions are oversimplistic, inconsistent and erroneous, and that Dr. Humphreys' helium diffusion data are actually consistent with a date of about 1.5 billion years for the Fenton Hill zircons. Although Humphreys (2008b) and Humphreys (2010) briefly mention Loechelt (2008a; 2008b; 2008c), Dr. Humphreys provides no detailed responses to Dr. Loechelt's models and his numerous criticisms. Loechelt (2009a) is a detailed rebuttal of Humphreys (2008b) and Loechelt (2009b) is a less technical summary of his response to Humphreys (2008b).
- The "dating" equations in Humphreys et al. (2003a) are clearly based on many questionable assumptions (including: isotropic helium diffusion in minerals, constant subsurface temperatures over time, ignoring the possibility of extraneous helium, etc.). The vast majority of Humphreys et al.'s critical a, b, and Q/Q0 values that are used in these "dating" equations are either missing, poorly defined, improperly measured or inaccurate. Using the best available chemical data on the Fenton Hill zircons from Gentry et al. (1982b) and Zartman (1979), the equations in Humphreys et al. (2003a) provide ridiculous "dates" that range from hundreds to millions of years old (average: 90,000 ± 500,000 years old [one significant digit and two unbiased standard deviations] and not 6,000 ± 2,000 years as claim by Humphreys et al., 2004).
- Nevertheless, a review of the available documents from Dr. Humphreys' critics shows a lot of agreement among us. For example, Whitefield (2008), Loechelt (2008c) and I all agree that Dr. Humphreys' Q/Q0 values are inflated. Many of us have also protested against Dr. Humphreys' mysterious changes in the Q values from Gentry et al. (1982a) and his inability to justify his Q0 value of only 15 ncc STP/μg despite the promise in Humphreys (2005a) to present his math "soon" in a Creation Research Society Quarterly (CRSQ) article.
- To begin with, the "dating" equations in Humphreys et al. (2003a) are based on many blatantly false assumptions (isotropic diffusion, constant temperatures over time, etc.) that cannot be dismissed with any claims of "generosity" to the "uniformitarians." As Loechelt (2008c, p. 8) keenly points out:
- "The RATE radiohalo theory proposes the following mechanism for the formation of polonium radiohalos. Radon gas escapes uranium bearing minerals, such as zircon, which are embedded in biotite crystals, and migrates to accumulation sites where it decays into polonium, thereby forming a radiohalo. This theory requires that the heaviest of all noble gases, radon, have the ability to leave its host mineral and travel scores of microns between biotite plates, all within the time constraint determined by the 3.8235 day half-life of 222Rn. On the other hand, the helium diffusion theory requires that this same biotite trap helium, the lightest of all noble gases, and hold it for thousands of years. Clearly, the RATE researchers were focused on two isolated phenomena (helium diffusion and radiohalos) rather than solving a more general problem, like noble gas migration in biotite. Ironically, the helium diffusion study and the polonium radiohalo study are published as consecutive chapters in the same [2005 RATE] book... [references from Vardiman et al., 2005 omitted]."
- More recently, Humphreys et al. (2004, p. 5) and Humphreys (2005b) continue to refer to their "granodiorite" samples from depths of 750 and 1,490 meters. ... A review of the scientific literature on the subsurface geology of the Fenton Hill borehole site indicates that about 75% of the GT-2 and EE-1 cores consist of gneisses (Laughlin, 1981, p. 308; Laney et al., 1981, p. 2) and that granodiorite is not encountered in the cores until depths of 2591 meters (my Figure 1) (Laney et al., 1981, p. 1; Laughlin et al., 1983; Burruss and Hollister, 1979; Sasada, 1989, Figure 2, p. 258). Information in Laughlin et al. (1983) and other references clearly indicate that Humphreys et al.'s 750 and 1,490-meter samples are gneisses (Figure 1).
- Because Dr. Baumgardner's conclusions are inconsistent with the results of professional geologists that have examined and analyzed the cores in great detail, I emailed him with a list of questions about the samples that he had collected for Humphreys et al. In his kind reply, Dr. Baumgardner described the core as consisting of dark gneissic "veins" surrounded by an "unaltered granodiorite" consisting of "large (typically, 2-3 mm)" pinkish grains. Although I requested any mineralogical (such as petrographic or X-ray diffraction analyses) or chemical data (that is, major oxides, minor and trace element analyses) that Dr. Baumgardner might have to support his claims, he provided none.
- Dr. Feeley writes:
- "Well, after the Q & A session Humphreys called me 'evil' for asking such a question (I thought it was a valid question, but Humphreys apparently didn’t and I don’t think he is a very nice man). I also told him that he had a problem because the core sample he showed in his talk from where his zircons were separated was clearly a gneiss and not a granodiorite (‘with schist veins through it’), as he claimed. I could see this from the back row, as could the undergraduate geology students in attendance. At this point he called me 'dumb' and asked if I had the guts to tell Baumgardner (who selected the core) that the sample was a metamorphic rock and not an igneous rock. Sure, I’d tell him. As we walked over to speak with Baumgardner, a young woman who identified herself as a Christian, scolded Humphreys for being mean and not behaving in a Christian-like manner by calling me evil and dumb. She didn’t think he was a very nice man either. To get back to the point, Baumgardner conceded that the core sample was indeed a gneiss and not a granodiorite. To his credit, Humphreys did begrudgingly apologize. Personally, I didn’t care about the apology, which wasn’t sincere anyway. I was more concerned that this guy was conducting expensive research on the age of the earth, yet couldn’t even tell the difference between a metamorphic rock and an igneous rock. Oh yeah, I forgot, he’s a creationist physicist and not a geologist."
- First of all, two zircons can have identical U/Pb dates and Pb/Pb isotope ratios, but still greatly differ in size, which affects Dr. Humphreys' a values, and have radically different absolute concentrations of lead, uranium, thorium and helium (that is, very different Q/Q0 values; my Appendix B). Secondly, Dr. Humphreys makes several bold assertions in the above paragraph that are flatly refuted by the chemical data in the very reference that he cites (i.e., Gentry et al., 1982b). Gentry et al. (1982b) show that uranium and thorium concentrations in the Fenton Hill zircons can vary by more than an order of magnitude even if the zircons are taken from the same section of the cores (my Appendix B). In the case of zircon 1A in Table B1 of my Appendix B, the uranium concentrations vary by more than an order of magnitude within the zircon!
- Because Dr. Humphreys collected his zircons from gneisses and not granodiorites (my Figure 1), he needs to realize that thermodynamic and other laboratory studies indicate that gneisses and their metamorphic zircons form under much greater metamorphic pressures than could ever have existed at depths of only 750 to 4,310 meters (Hyndman, 1985; Winkler, 1979). ... Considering that the metamorphic rocks of the Fenton Hill cores probably spent a lot of their history at depths greater than 15 kilometers, Dr. Humphreys is sadly mistaken when he believes that his modeling of helium diffusion in some zircons from current depths of 750 meters to 4.3 kilometers yield valid information on the beginning of the Earth's geologic history.
- Humphreys et al. (2003a, p. 17) states that the biotites from the "Beartooth gneiss" ("Beartooth amphibolite" in Humphreys, 2005b) and the "Jemez granodiorite" were extracted through "crushing, magnetic separation, and density separation with heavy liquids." However, silicate minerals can lose much of their helium through crushing (Trull and Kurz, 1993, p. 1314; Mussett, 1969, p. 298). Allowing personnel from the Institute for Creation Research (ICR) laboratory to grind the biotite specimens could have resulted in substantial helium loss and significant errors in Appendix B of Humphreys et al. (2003a).
- Gentry et al. (1982a) contains helium (Q) measurements of zircons from their Fenton Hill samples 0-6. While Humphreys (2000) simply listed the helium measurements from Gentry et al. (1982a), Humphreys et al. (2003a, post-conference version) in consultation with YEC R. V. Gentry concluded that the helium measurements in Gentry et al. (1982a) had "typographic errors" (see my Table 1). Their undocumented "corrections" to the measurements in Gentry et al. (1982a) usually included lowering most of the Q values by 10 times (my Table 1).
- As others (e.g., Isaac, 2008b) and I have noted, Dr. Humphreys has yet to reveal adequate details on how these "typographic errors" in Gentry et al. (1982a) were discovered and reliably corrected, and how the associated Q/Q0 values could remain unaffected. An unknown writer(s) at CreationWiki makes the following interesting statement about the discovery of the "typographic errors" in Gentry et al. (1982a):
- "The errors were discovered when Humphreys was doing the retention calculations for RATES [sic, RATE's] sample. He noticed an order of magnitude discrepancy in the absolute helium amounts. When he contacted Gentry, Gentry agreed that they probably were typographical errors."
- It is not known whether this statement is based on a rumor or first-hand knowledge from Dr. Humphreys and/or R. V. Gentry. If this account is true, R. V. Gentry agreed that his paper "probably" contained typographical errors after Dr. Humphreys obtain his results and noticed a discrepancy between his results and the data in Gentry et al. (1982a). Humphreys (2005a) also admitted that:
- "Gentry's original calculations are no longer available."
- If Dr. Humphreys and R. V. Gentry did not have R. V. Gentry's original calculations or laboratory notes, how do they know after more than 20 years that typographic errors had been made in Gentry et al. (1982a)? Was R. V. Gentry simply admitting to the possibility of "typographic errors" to help his friend, Dr. Humphreys, and the RATE project? Also, why were the Q values affected by the "typographic errors", but not the associated Q/Q0 values? How is this mathematically possible? Correcting errors in previous manuscripts is certainly honorable. However, authors should not agree to any "corrections" unless they can first review their original laboratory notes and confirm that copying, analytical or other errors were indeed made. In other words, scientists should not admit to making mistakes before seeing the evidence.
- Using the available information from Gentry et al. (1982a) and ignoring the possibility of extraneous 4He and 3He, I was unable to derive a Q0 of 15 ncc STP/μg for the zircons. Instead, I found that the assumptions in Gentry et al. (1982a) yield a Q0 of 41 ncc STP/μg (Appendix A). Loechelt (2008c, p. 5) also concluded that the assumptions in Gentry et al. (1982a) would yield a Q0 of about 40 ncc STP/μg and not 15 ncc STP/μg.
- Meanwhile, Humphreys (2005a) still won't adequately explain how he and supposedly Gentry et al. (1982a) calculated a Q0 of only 15 ncc STP/μg (also see my Appendix A) and why chemical data in another article by R. V. Gentry, Gentry et al. (1982b), indicate that Q0 is typically much greater than 15 or even 41 ncc STP/μg (perhaps as high as 800 ncc STP/μg; see Table B8 in my Appendix B).
- As discussed below, when my lower Q/Q0 values are entered into Dr. Humphreys' "dating equations", they often raise Humphreys et al.'s "helium diffusion dates" to well above 6,000 years and, in some cases, over one million years. In other cases, the revised Q/Q0 values actually lower the "ages" of the zircons to ridiculous values of only 200 years.
- Rather than always carefully measuring critical factors such as the lengths and widths of his zircons, Humphreys (2005a) admits that the sizes of the zircons in his 750-meter (2002) sample were never determined. Instead, he simply assumed that a was 30 microns.
- Specifically, Mussett (1969) showed that improper estimates of a can cause the argon diffusion coefficients (D values) to vary by over seven orders of magnitude at a given temperature (also see McDougall and Harrison, 1999, p. 147).
- Humphreys et al. (2003a, p. 6) describe a graph in Magomedov (1970, his Figure 3) and reproduce it in their Figure 5 (p. 6) (also see my Figure 2). The y-axis of the graph in Magomedov (1970) has the English units of "ln(D,σ)," where "ln" refers to natural log, D represents the diffusion coefficient and σ refers to electrical conductivity, which may influence diffusion in some crystals as cited in Girifalco (1964, p. 92-102), a reference used by Humphreys et al. (2003a). Based on helium diffusion results of zircons from the Fish Canyon Tuff (Reiners et al., 2002), Humphreys et al. (2003a, p. 6) conclude that the units on Magomedov's graph must be "incorrect" and that the actual units should be log base 10 D (log10 D). Based on this faulty assumption, Humphreys et al. (2003a, p. 6) manipulate the Magomedov (1970) data from natural log (ln) to log base 10 to comply with their data and the data in Reiners et al.'s (2002). As further discussed below, Dr. Humphreys' unjustified manipulation of the data in Magomedov (1970) exposes his inability to properly handle the literature, even with an English translation.
- Clearly, the data within Magomedov (1970) overwhelmingly indicates that he was using natural logs. Dr. Humphreys has absolutely no justification for arguing for a log base 10 interpretation of the Magomedov data and fudging Magomedov's helium diffusion data to support his YEC agenda. As discussed below, the ramifications of the natural log format in Magomedov (1970) undermine Dr. Humphreys' YEC agenda.
- According to Laughlin et al. (1983), sample 5 is a biotite granodiorite, whereas sample 6 consists of a gneiss and a biotite granodiorite (Table 1). Gentry et al. (1982a, p. 1130) admit that the low concentrations of helium in the zircons of these samples may not be in- situ radiogenic 4He:
- "In fact, at present we are not certain whether the minute amounts of He recorded from the deepest zircons (3930 and 4310 m [i.e., samples 5 and 6]) are actually residual He in the zircons or derived from some other source." [my emphasis]
- "Derived from some other source" could mean extraneous helium (see below) or possibly interferences from the analytical equipment. It's also possible that both the helium in samples 5 and 6 are in equilibrium with extraneous background concentrations that may include contributions from regional volcanic, hydrothermal and/or tectonic activities sometime in the recent geologic past (e.g., Harrison et al., 1986).
- So, Vbiotite / Vzircon = 0.0095 and not 1000.
- A scientist that peer-reviewed this essay decided to perform the calculations and verify Dr. Humphreys' conclusion that the amount of helium in the Fenton Hill biotite at a depth of 750 meters and the amount in the zircons of R.V. Gentry's sample 6 from a depth of 4310 meters were "almost exactly the same." ... The scientist then wrote the following comments to me:
- "Almost exactly the same???? The numbers are off by over an order of magnitude! I cannot find any mistake in my math, but then again, if Humphreys meant something else, he should have elaborated on his argument in the first place. What is worse, for Humphreys, is the fact that the biotite value is higher than the zircon value (which cannot happen through out-diffusion), which goes back to your point that one cannot claim that the biotite was in equilibrium with the zircon when the two minerals were separated by 3.5 kilometers."
- However, without giving any proper notification by inserting an errata statement in his paper, Dr. Humphreys changed the Q values in Humphreys et al. (2003a) after the conference and had the revised version posted on the ICR website. When Dr. Humphreys' "corrected" the Q values in Humphreys et al. (2003a), which included changing the Q value of sample 6 from ~0.2 to ~0.02 ncc STP/μg, his claim was no longer true.
- Although the above calculations and disputes over the accuracy of the values in Dr. Humphreys' documents are important, there is a danger that all of us (including Dr. Humphreys) could get bogged down in these numerical disputes and overlook the even more critical questions about Dr. Humphreys' behavior and claims. Dr. Humphreys needs to answer critical questions about his sloppy methodology and his flippant approach to scientific research and criticism from scientists. That is, why are the claims and numerical results of Dr. Humphreys and his allies so often shown to be wrong when other individuals perform their calculations (e.g., my Appendix A)? Why did he change the text in Humphreys et al. (2003a) after the 2003 International Conference on Creationism (ICC) without publicly announcing the changes with an errata statement? Where is the Creation Research Society Quarterly article promised in Humphreys (2005a) that would explain how he obtained a Q0 of only 15 ncc STP/μg? How can Dr. Humphreys in Humphreys (2005a) claim that any errors in Q and Q0 would cancel out and not affect his Q/Q0 values? What valid justification does Dr. Humphreys have for omitting sample 6 from his models, but including sample 5? etc. (see my Appendix C for further questions).
- His inconsistent use of one or two standard deviations seems to depend on which approach best serves his YEC agenda. As examples, Figure 13 in Humphreys (2005b, p. 55) uses 2σ, which helps to overlap the diffusion data with the creation model. In contrast, the errors on his high Q/Q0 values are only given in 1σ, which deemphasizes the errors associated with these values that are "crucial" components of his creation model (Humphreys, 2005b, p. 30).
- Using activation energy and diffusion coefficients from Magomedov (1970) (which are listed in footnote 16 of Gentry et al., 1982b), Humphreys et al. (2004, p. 10) performed some calculations and claimed that 60-micron long zircons (assuming a = 30 microns) from sample 6 should lose about 50% of their lead if they were exposed to 313°C for 1.5 billion years. Because the zircons supposedly have only lost about 10% of their lead (Humphreys et al., 2004, p. 9), Humphreys et al. (2004, p. 10) spuriously argue that the zircons must be much younger than 1.5 billion years old.
- Lee et al. (1997, p. 160, 161) list a more recent activation energy value (161 kcal/mol) and temperature-independent diffusion coefficient (approximately 3.9 × 109 cm2/sec) for lead in a gem-quality Sri Lankan zircon. The Lee et al. (1997) diffusion coefficient is 11 orders of magnitude larger than the measurement in Magomedov (1970), which was obtained on exceptionally metamict (radiation damaged) zircons. Inserting the values from Lee et al. (1997) into the same equation used by Humphreys et al. (2004, p. 9-10) (that is, Nicolaysen, 1957 in footnote 16 of Gentry et al., 1982b, p. 298) predicts only about 1% lead loss at 313°C over 1.5 billion years rather than a loss of approximately 50% as claimed by Humphreys et al. (2004, p. 10). Entering data from another lead diffusion in zircon study (Cherniak and Watson, 2000) into the Nicolaysen equation also predicts about 1% lead loss in the zircons over 1.5 billion years.
- My resulting "dates" with samples 1, ~3, 5 and 6 are listed in Table 4. The average of all of the "dates" in Table 4 is a ridiculous 90,000 ± 500,000 "years" old (one significant digit with two unbiased (n-1) standard deviations) with a range of 200 to 1,700,000 years old. Considering the faulty equations and assumptions in Dr. Humphreys' "creation" and "uniformitarian" models as further shown by Loechelt (2008c), I don't think that any reliable helium diffusion dates are possible with Dr. Humphreys' approach. Furthermore, after viewing the absurd range of "dates" using Dr. Humphreys' methods, YECs have no basis for criticizing the relatively minor problems with radiometric dating.
- YECs readily accept the existence of extraneous argon in igneous and metamorphic minerals because they improperly believe (see response here) that "undetected excess" argon nullifies K-Ar and Ar-Ar dating. Because helium atoms are much smaller than argon atoms, helium would tend to more readily move in and out of most minerals than argon. So, if YECs enthusiastically accept the existence of extraneous argon, why shouldn't they acknowledge that subsurface minerals (including zircons) could be substantially contaminated with extraneous helium? The answer is obvious. Extraneous helium is one of many factors that could completely nullify the YEC conclusions of Dr. Humphreys' Fenton Hill zircon study.
- Open systems not only mean that helium may flow out of zircons, but extraneous helium may periodically flow into them.
- The extraneous helium concentrations in at least the Baca 4 well approached or exceeded the helium concentrations that Humphreys et al. (2004) list for the zircons in samples 4-6 (my Table 1).
- Unless Humphreys et al. can thoroughly identify and subtract out any extraneous helium in their zircons and correct the other numerous problems with their work, no one should expect realistic results from their "creation" and "uniformitarian" models. For example, the extremely small Q/Q0 values predicted by the "uniformitarian" model in Table 5 of Humphreys et al. (2003a, p. 12) could be easily masked by extraneous helium concentrations of only 0.01 ncc STP/μg.
- Obviously, Dr. Humphreys has an invalid Lyell uniformitarian mindset that YECs so often accuse scientists of possessing. That is, Dr. Humphreys falsely believes that if the helium concentrations in surrounding biotites are now relatively low, then these concentrations must have always been low in the past. Dr. Humphreys simply fails to realize that the zircons may have been contaminated with extraneous helium over a prolonged period long ago. While abundant cleavage planes could have allowed extraneous helium to eventually dissipate from biotites in the distant past, the extraneous helium could substantially remain in the relatively impermeable zircons (see further discussions below).
- Dr. Humphreys simply fails to realize that the zircons may have been contaminated with extraneous helium many thousands of years ago. Extraneous helium from the lower crust or mantle may have periodically passed through Fenton Hill in the past just as the gas is currently passing through the nearby Valles Caldera (Smith and Kennedy, 1985; Truesdell and Janik, 1986), parts of the Española Basin (Manning, 2008), and in many other areas of New Mexico (Broadhead, 2006). The presence of uranium deposits in at least part of the GT-2 Fenton Hill core (West and Laughlin, 1976, p. 618) is another potential source of extraneous helium and indicates that at least at one time the Fenton Hill subsurface rocks were far more permeable for uranium-bearing fluids than what Humphreys (2005a) realizes.
- So, before Dr. Humphreys can use his "studies" to promote a religious agenda and overthrow nuclear physics and geochronology, he clearly needs to measure the 3He and 4He values on preferably fresh (not >30 years old) minerals and eliminate any possible effects from extraneous helium.
- Dr. Humphreys is assuming that natural pressures of 200-1,200 bars would not have closed or narrowed a significant number of fractures or other defects in his zircons, thereby decreasing the permeability of the zircons and lowering the zircon defect curve in his graph away from his "creation model" and towards his "uniformitarian model" (see my Figure B).
- Even if Dr. Whitefield's hypothesis is an insignificant factor, Dr. Humphreys fails to mention some important results in Dunai and Roselieb (1996). Dunai and Roselieb (1996) concluded that at high pressures of 250 bars, helium would take TENS to HUNDREDS OF MILLIONS OF YEARS even at high temperatures (700°C) TO PARTIALLY DIFFUSE out of garnets. Like zircons, garnets are "hard" silicate minerals. If it takes many millions of years for helium to just partially diffuse out of "hard" garnets at 700°C and pressures of 250 bars, what makes Dr. Humphreys believe that 200-1,200 bars of pressure might not significantly lower the diffusion of helium out of his "hard" zircons? It doesn't take much thought to realize that helium diffusion could be much greater from a rapidly heated, bare and fractured zircon in a laboratory vacuum than a zircon 750 to 4,310 meters in the subsurface encased in other minerals and possibly bathed in extraneous helium over long periods of time.
- Loechelt (2008c, p. 17) comments on his young-Earth multi- domain model (#4):
- "With the more retentive multi-domain diffusion model, there is now insufficient thermal budget in a young earth to cause enough helium loss. The combination that best fits the measured data is a multi-domain diffusion model in the context of an old earth with multiple thermal events occurring over the last 1.44 billion years."
- Dr. Humphreys and his allies argue that his helium in zircons study is "evidence" of "accelerated" radioactive decay, presumably during the "Creation Week" and/or "Noah's Flood." Besides vaporizing the zircons and releasing their helium, any acceleration of radioactive decay would release an enormous amount of heat and other radiation that would have fried Noah or created a molten Earth that would have been too hot to plant the "Garden of Eden" until long after the "Creation Week." Therefore, the very presence of any helium in zircons is incontrovertible evidence that accelerate radioactive decay as advocated by Dr. Humphreys and his allies never occurred. Whitefield (2008) notes that even the RATE YECs admit that the terrestrial temperature increase from their "accelerated" radioactive decay would have been about 20,400 degrees Kelvin, or more than three times hotter than the surface of the Sun. Morton and Murphy (2004) also quote YECs that readily admit that they have a "heat problem", including Dr. Humphreys. Humphreys (2000) and Humphreys (2005b) speculated on a "solution" to the YEC heat problem that involve the expansion of space. Morton and Murphy (2004) and Pitts (2009) show that Dr. Humphreys' "solution" is refuted by scientific observations.
- Dr. Loechelt's models are thorough and their underlying assumptions are definitely superior to anything that Dr. Humphreys has to offer. Nevertheless, as discussed earlier, possible effects from extraneous helium and high subsurface pressures as well as the unreliable a, b, Q/Q0 values, and other data that went into both Dr. Humphreys' and Dr. Loechelt's models do not allow anyone at this time to definitively determine the age of the zircons on the basis of helium diffusion.
- [Somewhere around p. 74, this article seems to shift from the directly scientific issues to issues of Humphreys' conduct as a scientist and debate participant in general. Although this is interesting and not irrelevant to the question of how his diffusion work should be received, I think it more profitable to move on to other sources at this point. There are also the lengthy appendices, but these are more technical and seem to cover the same ground as the main text. --Awc]
- When the scientific merits of the Fenton Hill study are examined, five specific flaws in the data analysis and modeling are found which are serious enough to invalidate the argument for accelerated nuclear decay. Furthermore, once these errors are corrected, forward modeling of the helium diffusion from these zircons produces retention values that are commensurate with the radiometric ages of the samples. Therefore, not only is the accelerated nuclear decay argument invalidated, but the scientific evidence supports the conventional 4.5 billion year age of the earth.
- Two fundamental flaws are usually seen in these arguments. First, they fail to demonstrate in the common case that experimental uncertainties result in errors of sufficient magnitude to completely invalidate the dating methods in question. Second, and perhaps more importantly, no credible alternative is given which can adequately explain the well- documented patterns in isotopic ratios which are repeatedly observed in terrestrial, lunar, and meteoric samples (Dalrymple, 1991).
- The ensuing eight-year research program, called RATE for Radioisotopes and the Age of The Earth, acknowledged that much larger quantities of nuclear decay have occurred in most geologic processes than could be explained by an earth only a few thousand years old (Vardiman et al., 2005; DeYoung, 2005).
- Most of the cases documented by the RATE team proved to be weak tests for their hypothesis because the other clocks were not independent (i.e. they were also based upon nuclear phenomena) and showed very little difference in time (i.e. 10-20% instead of 5-6 orders of magnitude).
- The notable exception was a helium diffusion experiment using zircon mineral samples (ZrSiO4 crystals) from deep geothermal test wells at Fenton Hill, New Mexico.
- In particular, there are five specific errors that were committed by Humphreys and his RATE colleagues in their helium diffusion modeling, two of which are serious enough to completely invalidate their conclusions. These five errors are expounded in the following discussion.
- 1. Helium retention measurements
- The first error traces back to the prior work by Robert Gentry and his original estimate of the helium retention ratio.
- The problem with this helium retention experiment, however, was not in the measurement of the current helium content of these zircon samples, but in the calculation of the total amount of helium generated from the α-decay of radioactive nuclei (Qo). This quantity was estimated using the ~80 ppm lead concentration measured at 2900 m, which was assumed to be representative of all the samples in the formation, regardless of depth. This assumption is not very good.
- The Precambrian basement rock type at Fenton Hill changes with depth over a scale of kilometers from gneiss to gneiss with mafic schist to biotite granodiorite and back to gneiss. Furthermore, dozens of cores from the Precambrian section showed a marked diversity of composition, texture, degree of alteration, and fracturing over distances of only a few centimeters (Laughlin et al., 1983). In fact, variations in the radioisotope content, or zoning, frequently occur in the zircon crystals themselves over a length scale of microns (Gentry et al., 1982b). Because of effects like these, current researchers active in the (U-Th)/He thermochronometry field typically follow the practice of measuring both the He and U-Th content from the same sample (Reiners et al., 2004). Unfortunately, this practice was not followed.
- Far more seriously, even if the ~80 ppm lead concentration is assumed to be a valid measure of the amount of radioactive decay in these zircons throughout the depth of the formation, one still cannot account for the ~15 ncc/μg value for Qo which was originally reported by Gentry and subsequently used in the RATE study. Since neither Gentry nor Humphreys have published details as to how they determined Qo, this discrepancy remains unexplained.
- Taking 40% as an upper limit, the minimum corrected value for Qo would be around 40 ncc/μg, which is well over twice the value of ~15 ncc/μg reported by Gentry and subsequently used in the RATE study. Humphreys maintains that the original calculations are correct, despite unpublished criticism. However, he has yet to provide an explanation as to how a helium content of only ~15 ncc/μg was determined (Humphreys, 2005b).
- A further compounding problem is the use of the lead concentration in the zircons as a proxy for the total amount of α-decay. Based upon a detailed isotopic analysis, Zartman (1979) concluded that the lead system showed signs of redistribution at the mineral grain level, even though no evidence for disturbance was found at the whole rock level. Using his measured concentrations of 328.78 ppm for uranium and 169.42 ppm for thorium and a decay time of 1440 Ma, a Qo value of 73.68 ncc/μg is obtained. This number will be used in the subsequent analysis instead of the original Qo value calculated by the Oak Ridge research team, with the correction for α-ejection being handled during the diffusion simulations (Meesters and Dunai, 2002b).
- The remaining errors committed by the RATE researchers all pertain to their diffusion model. This model comprises several components, including a physical geometry, surface boundary conditions, thermal history, and material properties. Remarkably, the RATE team managed to make mistakes in all four of these areas. The physical geometry will be addressed first.
- Hence, a 20 μm sphere, which has the same β value, is the appropriate equivalent geometry for the real crystals.
- Consequently, this error in the physical geometry had the effect of artificially increasing the helium retention ratios predicted by the RATE models.
- 3. Surface boundary conditions
- The rate at which diffusing helium atoms can leave a zircon crystal depends upon the environment in which the crystal is embedded. In many rocks, zircons are often found inside larger biotite crystals. The RATE researchers assumed that this was the case in their Fenton Hill study.
- In their published papers, the RATE team discuss a diffusion model by Bell (1945) which is capable of handling a system of two concentric spheres with different diffusion coefficients (Humphreys et al., 2003b; Humphreys, 2005a). Although the authors imply that this model is well suited for modeling the two material zircon/biotite system, they never actually use the model! Instead, they use a simpler model in which both materials have the same diffusion coefficients. The justification given for this simplification, despite the fact that the diffusivity of helium in biotite is much higher than that of zircon, is that “this approximation is generous to the uniformitarian point of view because it increases the time helium could remain in the zircons.” (Humphreys, 2005a, p. 49) Yet, in a classic bait and switch maneuver, this approximation is applied only to their young-earth creation model, and not to their old-earth uniformitarian model. In the old-earth model, the effect of the surrounding biotite is neglected altogether (Humphreys et al., 2003b, p. 184; Humphreys, 2005a, p. 53).
- From this figure it is apparent that below 300 °C, which is the temperature region of interest, the diffusivity of helium in biotite is 2-3 orders of magnitude higher than that of zircon.
- As in the case for the physical geometry, we encounter an error which effectively increases the helium retention for the young-earth model.
- All things considered, the errors mentioned up until this point are somewhat inconsequential to the ultimate question regarding the accelerated nuclear decay hypothesis. Although they demonstrate deficiencies in the RATE study, they cannot account for the several orders of magnitude discrepancy between their old-earth uniformitarian model and measured data. In contrast, the remaining two errors are far more serious and are of sufficient magnitude to invalid the conclusions of the Fenton Hill helium diffusion study.
- The first of these major errors in the RATE study is the use of a constant temperature profile in their old-earth uniformitarian model. The original purpose of the deep wells drilled at Fenton Hill was to study the suitability of this site for extracting geothermal energy. Recent volcanic activity has raised the geothermal gradient in the area (the rate at which temperature increases with depth in the earth) to over twice its typical value in continental crust. These elevated temperatures have been sustained for a relatively short period of time on a geologic timescale. The use of a constant temperature over time by the RATE team demonstrates their misunderstanding of the thermal history of the site as well as the meaning of the word “uniformitarian”.
- As can be seen in Fig. 3, the temperature over the last 500 million years was well below the current temperature. In fact, the volcanic activity which is responsible for the present-day elevated temperatures at the site was so recent that it appears as a vertical spike near zero on the far right-hand side of the figure! By using a constant temperature in their uniformitarian model, the RATE researchers unfairly handicapped the opposing old-earth position.
- Humphreys apparently read this figure backwards, supposing that time advanced from right to left instead1.
- Once again, it appears that Humphreys read this curve backwards.
- Apparently, the temperature values on these curves were never compared against the present-day well temperatures measured at the Fenton Hill site, otherwise this mistake would have been avoided. Perhaps Humphreys assumed that the time axes followed the common geologic convention of using positive numbers to represent time before present. However, thermal modeling would more likely have followed the convention of assigning zero to an event in the past and using positive numbers to represent elapsed model time.
- The final error committed by the RATE research team was also the most subtle. The modeling of the helium diffusion clock required an underlying understanding of the diffusion properties of the zircon mineral system. Using data from a laboratory experiment in which gas release from a zircon sample was measured at different temperatures, they extracted the parameters for a simple kinetic model.
- The problem with their interpretation of the results from this laboratory experiment is that the few parts per million of gas released at the lowest temperatures (175-255 oC) were insufficient for constraining the bulk helium diffusion behavior.
- Essentially, there are two distinct populations of helium atoms in the solid (A and B), each with different diffusion properties.
- Not only did the RATE researchers choose a simplistic kinetic model, but also their lack of discussion of the subject suggests that they were unaware of the existence of alternate models.
- Several (U-Th)/He thermochronometry studies document complex diffusion behavior. Anomalously high diffusivities were observed in the initial low temperature steps of helium diffusion experiments on titanite (Reiners and Farley, 1999).
- More significantly for the case of Fenton Hill, this same pattern of diffusion was later observed in the helium/zircon system (Reiners et al., 2004). Specifically, anomalously high diffusivities were seen in the early, low temperature stages of a stepwise heating diffusion experiment. This trend was repeatedly observed in many different samples with varying degrees of radioactivity and crystal damage from several different geologic contexts. After considering both U-Th zoning and radiation damage as possible causes for this anomalous behavior, a multi-domain diffusion model was again preferred. When different models were compared with experimental data, the best agreement was consistently found for those cases in which a small fraction of gas in the system (less than 2%) diffused at a much higher rate than the majority of gas (greater by a factor of 40 000 or more). These small gas domains would have little impact on the bulk diffusivity of a zircon crystal (Reiners et al., 2004, pp. 1872-1874).
- Additional evidence can be found in diffusion experiments involving spallogenic 3He released from proton irradiated minerals. ... When titanite samples from the Fish Canyon tuff were analyzed using this technique, excess 3He and 4He was released during the initial low temperature steps of the experiment (Shuster et al., 2003). The fraction of gas released during these steps was negligible compared to the total (~1% for 3He and 0.5% for 4He). These results corroborate the prior work that was done on the same samples by Reiners and Farley (1999).
- In summary, there are several important observations to note regarding these studies. First, anomalously high helium release is frequently observed during the low temperature steps of diffusion experiments involving minerals which are of geologic interest. In particular, zircon is one of these minerals (Reiners et al., 2004; Reiners, 2005). Second, researchers have successfully accounted for this anomalous behavior by using multi-domain diffusion models. A common feature of these models is the partitioning of a small fraction of gas to a low retentivity domain and the remainder to a high retentivity domain. Because of this unequal partitioning, the low retentivity domain has little effect on the bulk helium retention properties of the material over time, despite the domain’s higher diffusivity. Finally, the work of these scientists is very relevant to the study at Fenton Hill. Farley, Reiners and Shuster were all members of the same research group that performed the helium diffusion experiments for the RATE team. Ironically, Humphreys and his young-earth colleagues ignored the published works and practices of the same experts whom they contracted to do their laboratory work.
- [Sec. 4. "A corrected model" goes into details that are acientifically crucial, but not needed for the aSK article. --Awc]
- If the reader is perplexed at this point as to how an old-earth model with a 1.44 billion year timescale can show more helium retention than a young-earth model with a 6000 year timescale, the answer is simple: the kinetic model. The old-earth model uses a multi-domain diffusion model whereas the young- earth model, like the RATE study, uses a single-domain diffusion model. The difference is that important. It is hard for a realistic single-domain diffusion model to show significant helium retention past a few thousand years.
- If the kinetic model is so important, then what would a young-earth model look like with a multi- domain diffusion model? Figure 8 answers this question. The young-earth model goes from excessive depletion to excessive retention. With the more retentive multi-domain diffusion model, there is now insufficient thermal budget in a young earth to cause enough helium loss. The combination that best fits the measured data is a multi-domain diffusion model in the context of an old earth with multiple thermal events occurring over the last 1.44 billion years.
- The old-earth model matches the revised measurements much better than any of the young- earth models considered. The RATE team claimed that essentially no helium would be left in these zircons if they were much more than a few thousand years old. However, direct computation has demonstrated otherwise – The helium content and the ~1.5 billion year radiometric age of these zircons are in very good agreement. Since no anomaly exists, there is no scientific need to postulate the existence of exotic physics, like accelerated nuclear decay, to explain the phenomenon.
- Not only does this result deprive the accelerated nuclear decay hypothesis of its best case, it actually counts as evidence against accelerated nuclear decay. Two independent clocks (nuclear decay and helium diffusion) are now in agreement on the billion year age of these rocks. Now the accelerated nuclear decay hypothesis requires accelerated diffusion as well. At some point accelerating natural processes becomes an untenable scientific position, and one must start reading nature’s “clocks” at face value.
- [extensive appendices --Awc]
- A general critique of this work by Dr. Kevin R. Henke appears elsewhere and I will not repeat most of those issues here, beyond mentioning that there are some serious questions as to how RATE calculated the ratios of theoretical to actual residual helium contents in the zircons (their Q/Q0 values). Rather, I will discuss the ability of the RATE conclusions to predict what is observed in other studies of helium in zircon crystals.
- In recent years, researchers like Dr. Kenneth Farley of the California Institute of Technology and Dr. Peter Reiners of Yale University have used helium-based age measurements to determine something of the cooling history of the zircon crystals. The uranium/lead age gives the time of initial formation, while the helium age tells when the crystal cooled to a temperature at which the helium was essentially all retained. These techniques can also be applied to other minerals such as titanate and apatite. Farley and Reiners and have developed the sophisticated laboratory equipment needed to accurately analyze microscopic crystals for the different isotopes of concern.
- Having made these predictions, the next step is to compare them with data from studies on zircons that are found at ambient temperatures and are not likely to have been at elevated temperature during the last 6000 years (RATE’s estimate of the age of the earth). There are several studies in the literature that report such data. The first was published by Reiners, Farley and Hickes. ... The zircons from the deepest section, prior to tilting, have helium contents only about 1 percent of the theoretical helium that should have formed during 1.5 billion years of radioactive decay. The helium level of the uppermost rocks is about 10 percent of the theoretical maximum. Those helium levels are hard to reconcile with RATE’s ideas about the age of the earth. According to RATE this rock formation is only about 6000 years old. How then could zircons from near the surface (at temperatures even lower than the 100EC I used for my diffusion calculation) have lost so much of their helium?
- Thus, many of the zircons from these sediments have helium ages of less than one percent of the uranium/lead age as well as correspondingly low helium contents. The results of helium measurements from these detrital samples are significant because there is no conceivable scenario for those zircons to have been exposed to elevated temperature (>100EC) during the last 6000 years. These sediments must have been eroded from near the surface in the mountains of northern India. To have eroded during the last 6000 years they could not have been at great depths beneath the surface. Thus, they could not have been exposed to elevated temperatures during the last 6000 years. This leaves the question of how the zircons that have certainly been at low temperatures during a time span that exceeds the creationist estimate of the age of the earth could have lost most of their helium. There simply has not been enough time for the helium to have diffused out. Clearly the real answer to this question is that the zircons are millions or billions of years old and that most of the helium diffused out during a time when the crystals were exposed to higher temperatures that corresponded to much faster diffusion rates. The trouble is that RATE’s idea of the age of the earth does not admit enough time for that to have happened.
- The RATE study claims to have correctly predicted the helium contents of zircons from various depths (and temperatures) in the Fenton Hill well. That may or may not be the case, depending on the validity of the residual helium calculations in that study. In any case, the RATE "theory" totally fails to predict the helium contents of other zircons found at different sites in Asia and North America. The zircons have clearly lost more helium than could be explained by 6000 years of diffusion at low temperatures.
- In the interest of responsible science, the RATE team members should carefully consider why their results are so different from everyone else’s. In particular they should have more carefully evaluated the possibility that helium from external sources got into their zircons and added to the radiogenic helium formed by uranium and thorium decay. They should have also considered the very complex thermal and geologic history of a site so close to a volcano. They should have examined whether their specimen preparation technique might have induced some unusual behavior in the zircon crystals that accelerated the diffusion rate measurements. Finally, they should have repeated their lower temperature (down to at least 100C) experiments with helium in the zircons from the Fenton Hill well to show that they had reproducible results. Real science needs to be duplicated to prove its validity. RATE certainly has no grounds to declare the entire science of radiometric dating to be invalid based on a study that apparently involved only two published diffusion tests (only one of which actually showed the low temperature fast diffusion rates essential to their "theory"). In short, RATE needs to do a better job of explaining their results if they want to be taken seriously by mainstream scientists.
Radiohalos in Granites