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- Dury, Jack, 1993-
(författare)
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Dealing With Reservoir Effects in Human and Faunal Skeletal Remains : Understanding the radiocarbon dating of aquatic samples
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Archaeology relies on the ordering of past events to study cultural developments. This has traditionally been achieved by looking at the stratigraphic depths of materials relative to one another. In this way, chronologies of past technological progressions and stylistic changes can be built. The introduction of radiocarbon dating in the 1950s revolutionised archaeology, allowing for direct, numerical estimates of a sample’s age. This allowed for more detailed past chronologies than was previously possible. Radiocarbon dating utilises the radioactive decay of carbon-14 (radiocarbon, 14C) to estimate a sample’s age with older samples having less 14C. Shortly after the introduction of radiocarbon dating, however, it was demonstrated that 14C is not evenly distributed globally. Typically, there is less 14C in marine (and sometimes freshwater) systems compared to the atmosphere. This results in aquatic samples appearing older than they are, a phenomenon known as a ‘reservoir effect’. When radiocarbon dating material from archaeological sites with marine activity, this is an important consideration. With aquatic resources being vital for human populations across the globe and for millennia, the ability to interpret aquatic radiocarbon dates is incredibly important. Making use of radiocarbon dates without properly handling any reservoir effects have proved problematic, sometimes resulting in archaeologically incorrect chronologies being constructed. Reservoir effects can, however, be managed. This thesis demonstrates how archaeologists should interpret radiocarbon dates from aquatic samples, avoiding erroneously-old age estimates. Through careful sample selection, considering complicated carbon source mixing, measuring the scale and variability of reservoir effects within a single ecosystem and using prior knowledge about a sample’s age, the dating of aquatic material can be greatly improved. This thesis also details a novel method of dating teeth, reducing uncertainty, and concomitantly estimating the extent of the reservoir effect. This was achieved by dating dental increments, combined with complex modelling. It is clear that there is no single method of handling reservoir effects, and methods for dealing with reservoir effects will differ depending on the archaeological site and specific research question. In this thesis, novel and existing methods of dealing with reservoir effects are demonstrated by considering five case studies from four archaeological sites:At the site of Hamanaka 2 (Rebun Island, Japan), it is demonstrated that by carefully selecting samples without reservoir effects, the dating of the stratigraphy of the site can be accurately modelled. Concerning the cemetery site of Rounala (northern Sweden), it is demonstrated that by carefully reconstructing complex human diets, the dating of humans can be modelled to a high resolution. This has implications for the understanding of the Church’s relationship with the cemetery. At the site of Ekven (Chukotka, Bering Strait) reservoir effect variability between species is carefully described. A more detailed understanding of regional reservoir effects allows for more accurate dating of human remains from the marine hunting Old Bering Sea culture. More accurate dating of human remains allows for the refining of existing Old Bering Sea culture chronologies. Finally, concerning the material from Resmo (Ӧland, Sweden), a novel dental wiggle matching model is presented as a possible method for reducing dating uncertainty in individuals with a marine dietary component.
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| 3. |
- Larsson, Anton, 1994-, et al.
(författare)
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Jordfallet at Bohus : Reinterpreting the 14C dating of a medieval landslide event
- 2022
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Ingår i: Radiocarbon. - 0033-8222 .- 1945-5755. ; 64:5, s. 1239-1255
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Tidskriftsartikel (refereegranskat)abstract
- Radiocarbon (14C) dating has, since its inception, become an integral part of disciplines such as geology and archaeology, underpinning many key findings made by researchers in the past seven decades. As 14C dating develops, the need arises to revisit older findings and legacy data which may well contain laboratory errors or post-analysis misinterpretations. In this paper we examine one such finding from Sweden, namely the 1958 14C dating of the great Jordfallet (“the Earthfall”) landslide, which was published in the very first volume of Radiocarbon in 1959. We further trace how the results of this 14C dating were misunderstood in a time prior to modern radiocarbon calibration, and the impact which this mistake has had throughout academic publications, state reports and local heritage literature through the course of over sixty years. Because of this flawed interpretation the credible date of 1249 AD given to the landslide by historical sources has been overlooked. Instead, a series of dates from the mid-12th and early 13th centuries have been attributed to the landslide event based on erroneous radiocarbon analysis, a mistake which has substantial implications for the understanding of both regional and international history in medieval Scandinavia.
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