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This digital document is a journal article from Palaeogeography, Palaeoclimatology, Palaeoecology, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Gastropod shells are commonly preserved in Quaternary sediments, but are often avoided for radiocarbon dating because some taxa incorporate ^1^4C-deficient carbon during shell formation. Recently, Brennan and Quade [(1997) Quat. Res. 47, 329-336] found that some minute taxa (Vallonia, Pupilla, and Succineidae) appear to yield reliable ^1^4C ages for late Pleistocene samples. A more rigorous evaluation of the ^1^4C inventory of minute gastropods is presented here, which involved measuring the ^1^4C activity of specimens collected live in two geologic settings that maximize the potential for ingestion of 'old' carbon: (1) alluvium dominated by Paleozoic carbonate rocks, and (2) adjacent to extant springs with highly ^1^4C-deficient water present at the surface. We found that several minute taxa, including Vallonia, incorporate significant and variable amounts of old carbon (~2 to >30%) during shell formation. The ^1^4C activities of the land snails Pupilla blandi and Euconulus fulvus, however, are indistinguishable from the ^1^4C activity of live plants. The ^1^4C activity of the semi-aquatic gastropod Catinella sp. (Family: Succineidae) deviates from modern values in the presence of ^1^4C-deficient water by an amount equivalent to ~10% of the local carbon-reservoir effect. These results imply that at least some minute gastropods can provide reliable ^1^4C ages even when ^1^4C-deficient carbon is readily available. To demonstrate an application of our findings, we ^1^4C-dated shells from P. muscorum, E. fulvus, and Succinea sp. (Family: Succineidae) recovered from the Coro Marl, a late Pleistocene spring-fed marsh deposit exposed at the Murray Springs Paleoindian site in the San Pedro Valley of southern Arizona, USA. Radiocarbon ages obtained from the minute gastropods show that the unit was deposited between ~25@?000 and 13@?000 ^1^4C years ago. The marl is situated >15 m above the modern water table at Murray Springs, and is similarly positioned in discontinuous outcrops along a ~150-km stretch of the San Pedro Valley. Thus, the ^1^4C ages of minute gastropods presented here may be used to infer the timing of high water-table levels throughout the valley. ... Read more

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Radiocarbon Dating. Radiometric Dating, Radionuclide, Before Present, Beta Decay, Exponential Decay, Carbon-14, Age of the Earth, Environmental Radioactivity, Willard Libby, Hessel de Vries, Calibration Curve, Half-Life, Enrico Fermi, Article Sources and Contributors, Image Sources, Licenses and Contributors ... Read more

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This digital document is a journal article from Journal of Archaeological Science, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The chronology of prehistoric Sami settlement sites has previously been established by conventional radiocarbon dating of bulk charcoal samples associated with hearths from sunken hut floors (stallo-foundations). Here we present results of a comprehensive dating exercise of stallo-foundations in the alpine area of northern Scandinavia using Accelerator Mass Spectrometry (AMS) radiocarbon dating of charcoal. Over a 3km^2 study area, AMS calibrated ages of hearth charcoal from 22 stallo-foundations across 12 sites securely date these features to between cal. AD 640 and AD 1180. Only small variations in age were found between charcoal samples from different areas of a given hearth. Statistical analysis of all the charcoal AMS radiocarbon dates obtained reveals that 12 stallo-foundations across nine sites are contemporaneous and date to the Viking Period (AD 800-AD 1050). The tightly constrained AMS-based chronology of stallo-foundations contrasts with the existing chronology based on conventional radiocarbon analysis, which places these features within a significantly greater time-frame of between AD 600 and AD 1900, with most dates ranging between AD 800 and AD 1350.This discrepancy is likely to result from the necessity of collecting composite hearth charcoal particles, which may originate from different phases of occupation, in order to achieve the required final carbon content for conventional radiocarbon analysis. We argue that the new AMS-based radiocarbon chronology of stallo-foundations presented here supersedes the existing chronology based on conventional (Gas Proportional counting) radiocarbon analysis and we advocate the use of AMS radiocarbon dating in future hearth investigations. ... Read more

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Glottochronology is an approach in historical linguistics for estimating the time at which languages diverged, based on the assumption that the basic (core) vocabulary of a language changes at a constant average rate. This assumption, originally suggested by Morris Swadesh, is based on an analogy with the use of carbon dating for measuring the age of organic materials, in that a "lexical half-life" is estimated. The method estimates the length of time since two or more languages diverged from a common earlier proto-language, by counting the number of words that have been replaced in each language. This yields an estimated date of origin for those languages. Glottochronology is an adjunct to lexicostatistics, with which it has been sometimes confused. ... Read more

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This digital document is a journal article from Journal of Archaeological Science, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Archaeologists have long recognized the problem of the ''old wood'' effect in radiocarbon dating charcoal and wood samples, the age of which may be hundreds of years older than their use by humans. Such problems have resulted in significant changes in how most researchers select wood and charcoal samples for ^1^4C dating, with many now using relatively short-lived carbonized materials for dating. Despite the significant strides made in our understanding of the potential biases of the ''old wood'' effect, little emphasis has been placed on the possible impacts of dating ''old shell'' in archaeological deposits. The use of marine shell for ^1^4C dating is widespread in coastal areas around the world, including a growing emphasis on the dating of individual shell artifacts via Accelerator Mass Spectrometry (AMS). In dating shell artifacts, we have obtained several dates older than associated ^1^4C dates for short-lived subsistence remains from the same deposits, including great disparities (>10,000years) and more subtle differences (>=100years). These discrepancies appear to be due to the use of old shells by humans to make beads and other artifacts, including shells collected from fossil deposits, older archaeological sites, and beaches. The problems caused by the use of old shells to make beads and other artifacts are surmountable through careful sample selection, analysis of multiple ^1^4C dates on a variety of materials, and proper calibration procedures. ... Read more

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This digital document is a journal article from Quaternary Science Reviews, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Accurate geochronologies are the key for comparison of palaeoclimate records. In order to clarify problems concerning the geochronology of glacier fluctuations we dated palaeosols in moraines in the Kebnekaise mountain region of Swedish Lapland. These palaeosols already have been dated several years ago using bulk samples of the palaeosols and yielded ages of 6180-5790 and 2750-2100calyrBP. In an attempt to evaluate the sources of contamination associated with bulk samples these soils were re-dated by using Coleoptera fragments, Cenococcum geophilum spores, humic acids and woody plant tissues. The new dates reveal that the two palaeosols found within the moraines represent much longer periods of time than was previously assumed. Soil formation periods can be distinguished for periods 7800-7580, 6300-4080, 2450-2000 and 1170-740cal yr BP. These age groups point to differentiated soil formation processes, resedimentation, bioturbation and/or cryoturbation. The results show that dated terrestrial macrofossils from glacial moraines indicate climate changes that are in accordance with other proxy records in northern and central Scandinavia and in certain times off-phase with glacier fluctuations in southern maritime Norway. This throws light on possible changing interaction of forcing factors during the Holocene. ... Read more

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This digital document is an article from World of Earth Science, brought to you by Gale®, a part of Cengage Learning, a world leader in e-research and educational publishing for libraries, schools and businesses.The length of the article is 666 words.The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase.You can view it with any web browser.A comprehensive guide to the concepts, theories, discoveries, pioneers, and issues relating to topics in earth science. Its encyclopedic approach offers entries that are written in easy to understand language. ... Read more

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This digital document is an article from Archaeology in Oceania, published by Thomson Gale on October 1, 2006. The length of the article is 2863 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser.

Citation Details
Title: Radiocarbon dates for earth mounds on the Adelaide River, Northern Australia.(Research Report)
Author: Sally Brockwell
Publication: Archaeology in Oceania (Magazine/Journal)
Date: October 1, 2006
Publisher: Thomson Gale
Volume: 41Issue: 3Page: 118(5)

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This digital document is an article from World of Earth Science, brought to you by Gale®, a part of Cengage Learning, a world leader in e-research and educational publishing for libraries, schools and businesses.The length of the article is 3273 words.The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase.You can view it with any web browser.A comprehensive guide to the concepts, theories, discoveries, pioneers, and issues relating to topics in earth science. Its encyclopedic approach offers entries that are written in easy to understand language. ... Read more

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This digital document is an article from Journal of Shellfish Research, published by National Shellfisheries Association, Inc. on December 1, 2008. The length of the article is 6003 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available immediately after purchase. You can view it with any web browser.

Citation Details
Title: The feasibility of bomb radiocarbon analysis to support an age-at-length relationship for red abalone, Haliotis rufescens Swainson in northern California.(Abstract)
Author: Robert T. Leaf
Publication: Journal of Shellfish Research (Magazine/Journal)
Date: December 1, 2008
Publisher: National Shellfisheries Association, Inc.
Volume: 27Issue: 5Page: 1177(6)

Article Type: Abstract

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This digital document is an article from UXL Encyclopedia of Science, brought to you by Gale®, a part of Cengage Learning, a world leader in e-research and educational publishing for libraries, schools and businesses.The length of the article is 541 words.The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase.You can view it with any web browser.This collection of entries covers major areas of science including: biology, genetics, microbiology, astronomy, chemistry, physics, engineering, technology, geology, weather, archaeology, psychology, mathematics, and medicine, and provides readers with a wide range of up-to-date, relevant, and accurate information. ... Read more

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This digital document is an article from Fishery Bulletin, published by National Marine Fisheries Service on October 1, 2008. The length of the article is 8731 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available immediately after purchase. You can view it with any web browser.

Citation Details
Title: Age validation of Dover sole (Microstomus pacificus) by means of bomb radiocarbon.(Report)
Author: Craig R. Kastelle
Publication: Fishery Bulletin (Magazine/Journal)
Date: October 1, 2008
Publisher: National Marine Fisheries Service
Volume: 106Issue: 4Page: 375(11)

Article Type: Report

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