Lewisville, Texas : an Oldie but Goodie.

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Lewisville, Texas : an Oldie but Goodie.

Postby uniface » Mon Jun 22, 2015 3:40 pm

William B. Topping's stuff -- except for the paper with Firestone (who subsequently annonymized him in citations as "et al.") -- has been memory holed. Here's a paper he wrote that deserves wide attention:

Lewisville Revisited: A North American Paleo-Indian Site more than 26,000 years old.

In the classic by H. M Wormington, Ancient Man in North America, there is a short discussion about the Lewisville, Texas, Paleo-Indian site in which radiocarbon testing from two different features returned dates more than 37,000 years old (1957: 58-59). A controversy followed over whether or not the fluted point had been “planted,” or whether or not the “hearths” were actually features produced by human activity (Brannon et. al., 1957; Crook and Harris, 1957, 1962; Ferguson and Libby, 1962).  In 1985 a study of the site was made possible because of lower water levels caused by drought; the Trinity river had been damned and water had covered the site for many years. The study was conducted by the Illinois State Geological Survey (Environmental Geology Notes 109, 1985) and primarily used comparative Moessbauer analyses of samples from the hearth as well as samples of lignite from the nearby Woodbine formation in an effort to determine whether or not the Paleo-Indians had burned “lignite” to yield a falsely very old date. Lignite is simply coal, but very low grade and fibrous to woody in its composition.

A careful inspection of the report is instructive. The preface to the report begins: “...lignite in hearth residues would give older than actual ages by radiocarbon dating. X-ray diffraction proved inconclusive; however, Moessbauer spectroscopy indicated that hematite, a pyrite combustion product, was present in the ash. From this evidence we conclude there is some support for this hypothesis [bold here and below author] (Shiley et. al. 1985: 1).”  Anyone reading the preface probably would come to the conclusion that lignite had contaminated the samples. However, on careful reading it is clear that in fact there is “no support whatsoever” for the hypothesis that lignite was used by the Paleo-Indians at Lewisville. Part of the study involved obtaining another radiocarbon date from one of the hearths. The date obtained (TX-2A) was 26,610 300 B.P (Shiley et. al.: 2). This date was much younger than dates originally obtained, but radiocarbon pretreatment methodology had improved substantially in the two decades that had passed since the original dates were obtained. In a very thorough comparative analysis of “burned Woodbine lignite” and the ash from the actual hearths, the key to the suggestion that there was “some support” for the hypothesis that lignite had been used lies in one simple statement about a particular aspect of the research: “Of the hearth samples analyzed, only the ash from the modern all-night lignite fires ...showed any appreciable increase in iron over that found in surrounding soil (Shiley et.al.: 3)” The conclusion apparently was drawn that “iron” (pyrite) = “lignite only,” and therefore lignite must have been used by the Paleo-Indians.

The analysis of the rare earth elements resulted in the following conclusion: “ ...it dramatically illustrates that the rare earth composition of Woodbine Formation lignite and its corresponding ash are very similar to one another, but are not similar to the soil or the hearth samples. The rare earth composition of the surrounding soil follows the same pattern as that of the hearths. From this data, it is reasonable to provisionally conclude that Woodbine Formation lignite was not burned in the hearths (Shiley et. al.: 5).” X-ray
diffraction was even more clear: “An authogenic kaolinite characteristically found in the lignites DJ-2 and DJ-5 and in the all-night fire ash (DJ-3) was not found in any of the hearth samples (Shiley et. al.: 6).” In the conclusion there is the statement: “From 'fingerprints' obtained from neutron activation analysis of the hearth samples, it was reasonable to provisionally conclude that no Woodbine Formation was burned in the hearths. Furthermore, perhaps because of concentration problems, pyrite combustion products were not detected using X-ray diffraction (Shiley et. al.: 10). This is followed by this statement: “The use of Moessbauer spectroscopy, on the other hand, produced positive results. Hematite, a pyrite combustion product, was found in hearth 22. We conclude that there is some support for the hypothesis that Woodbine Formation lignite was burned in this hearth, thus increasing the apparent age (radiocarbon date) of the hearth material (Shiley et al.: 10).”

This statement, which is very misleading, is completely out-of-context. Above, in the report, are two very important clues to the obvious misinterpretation. First is a section related to the Moessbauer analysis: “Pyrite decomposition products were positively identified only in the samples from the all-night fires and the 35- to 40-cm lining of hearth 22...(Shiley et. al.: 6).” Second is the logic pursued: “Because hematite, a combustion product of pyrite, was found in the samples from hearth 22, which had a controversial radiocarbon date of 26, 610 B.P., we found some support for the suggestion that small quantities of Woodbine Formation lignite were burned in this hearth. The result would be a mix of carbon dated > 37,000 radiocarbon years with younger carbon-14 materials (Shiley et al.: 9).”  What complicated the analysis was the oversight of the mobility of irons, and special chemical or environmental conditions that foster pyrite buildup: “Bacteria have been suggested to cause deposition, or at least to catalyze deposition, of ferric hydroxide deposits such as bog iron ores....Precipitation of iron sulfides such as pyrite may also be aided by sulphur-reducing bacteria (Boggs 1987: 75).” Pyrite is FeS2 (Boggs: 30) and the sulphur is easily oxidized to form hematite which is 2Fe2O3. There are particular conditions that foster the buildup of pyrites: "Iron sulfides, particularly pyrite (FeS2 ), are forming in black muds that accumulate under reducing conditions in stagnant ocean basins, tidal flats, and organic-rich lakes....hematite (Fe2O3) is precipitated under oxidizing conditions at the pHs commonly found in the ocean and surface waters, siderite (FeCO3) forms under moderately reducing conditions, and pyrite (FeS2) forms under moderate to strong reducing conditions (Boggs: 94-95).”  “Authogenesis” refers to the postdepositional manufacture of new minerals, and the primary process is the formation of pyrites under reducing conditions (Boggs: 273-274). Iron is common, and it reduces and transports rapidly and very efficiently and rapidly under conditions that most favor transport: a water environment. The damning of the Trinity River provided a perfect setting for the manufacture of pyrites, and thus “had to have” transported irons into the features. In fact, the bulk of the data and associated analyses in the report are clear: no lignite was present in the hearth samples. The report mentions the “controversy” of the radiocarbon date obtained, and probably (almost certainly) explains why the authors suggested the possibility of lignite contamination when, in fact, there was no evidence for that conclusion at all.

Simply put, the date obtained in 1985 was at odds with worldview “then” (but no longer is, primarily due to the pioneering efforts of Dennis Stanford, Henry T. Wright and others). As a factual matter, we now have (and for many years have had, but unknown to the public) a reliable radiocarbon date for a Paleo-Indian site in North America that is more than 26,000 years old, and evolving evidence suggests that the date might be much older still (Firestone and Topping). The Lewisville radiocarbon date of “at least” 26,000 yrs bp rcy should be regarded as the new Paleo-Indian baseline, and very probably a minimal age for the peopling of the Americas.

(former google.doc URL no longer exists. Just like his scrib.doc Baldwin Memorandum has disappeared).

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