29,270 research outputs found

    Connecting and dating with tephras: principles, functioning, and application of tephrochronology in Quaternary research

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    Tephrochronology, the characterisation and use of volcanic-ash layers as a unique chronostratigraphic linking, synchronizing, and dating tool, has become a globally-practised discipline of immense practical value in a wide range of subjects including Quaternary stratigraphy, palaeoclimatology, palaeoecology, palaeolimnology, physical geography, geomorphology, volcanology, geochronology, archaeology, human evolution, anthropology, and human disease and medicine. The advent of systematic studies of cryptotephras – the identification, correlation, and dating of sparse, fine-grained glass-shard concentrations ‘hidden’ within sediments or soils – over the past ~20 years has been revolutionary. New cryptotephra techniques developed in northwestern Europe and Scandinavia in particular and in North America most recently adapted or improved to help solve problems as they arose, have now been applied to sedimentary sequences (including ice) on all the continents. The result has been the extension of tephra isochrons over wide areas hundreds to several thousands of kilometres from source volcanoes. Taphonomic and other issues, such as quantifying uncertainties in correlation, provide scope for future work. Developments in dating and analytical methods have led to important advances in the application of tephrochronology in recent times. In particular: (i) the ITPFT (glass fission-track) method has enabled landscapes and sequences to be dated where previously no dates were obtainable or where dating was problematic; (ii) new EMPA protocols enabling narrow-beam analyses (<5 um) of glass shards, or small melt inclusions, have been developed, meaning that small (typically distal) glass shards or melt inclusions <~10 um in diameter can now be analysed more efficaciously than previously (and with reduced risk of accidentally including microlites in the analysis as could occur with wide-beam analyses); (iii) LA-ICPMS method for trace element analysis of individual shards <~10 um in diameter is generating more detailed ‘fingerprints’ for enhancing tephra-correlation efficacy (Pearce et al., 2011, 2014; Pearce, 2014); and (iv) the revolutionary rise of Bayesian probability age modelling has helped to improve age frameworks for tephras of the late-glacial to Holocene period especially

    Measuring radiation in the environment following the Fukushima nuclear disaster, Japan

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    A group of scientists and technical staff from Toshiba Company, including Dr Hirokazu Kanai, undertook field trials at the station using a newly-developed, portable, two-dimensional gamma-ray visualization system known as a “Gamma Camera”

    Stratigraphy, age, composition, and correlation of late Quaternary tephras interbedded with organic sediments in Waikato lakes, North Island, New Zealand

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    Cores from 14 peaty lakes in the central Waikato region, northern North Island, contain a sequence of 41 well-preserved, mainly macroscopic, occasionally bedded, ash and lapilli layers ranging in thickness from c. 2 to 110 mm and interbedded with fine-grained organic lake sediment. The layers, whose field and compositional properties are described in detail, are distal airfall tephras that were erupted between c. 17000 and c. 1800 Âč⁎C years ago from six rhyolitic and andesitic volcanic centres located c. 70-200 km from the Waikato sites: Taupo (5 tephras), Okataina (7), Maroa (1) (rhyolitic); Mayor Island (2) (peralkaline); Tongariro (11), and Egmont (15) (andesitic)

    Quaternary volcanism, tephras, and tephra-derived soils in New Zealand: an introductory review

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    This two-part article comprises brief introductions to (1) volcanism and its products in general and to the broad pattern of Quaternary volcanism and tephrostratigraphy in North Island, and (2) the ensuing tephra-derived soils of North Island. Part 1 derives mainly from Smith et al. (2006), Leonard et al. (2007), and Lowe (2008a). Other useful reviews include those of Neall (2001), Graham (2008: Chapter 7), Wilson et al. (2009), and Cole et al. (2010). Recent reviews on tephras include Shane (2000), Alloway et al. (2007), Lowe (2008b, 2011), and Lowe et al. (2008a, 2008b). A history of tephra studies in New Zealand was reported by Lowe (1990). Part 2 describes the distribution and character of the main tephra-derived soils, these being Entisols and Andisols (mostly Vitrands and Udands) and Ultisols (Lowe and Palmer, 2005). Books on these and other soils in New Zealand include NZ Soil Bureau (1968), Gibbs (1980), McLaren and Cameron (1996), Cornforth (1998), and Molloy and Christie (1998). An excellent overview is the web-based article by Hewitt (2008), and encyclopaedic reviews by Neall (2006) and McDaniel et al. (2011) include New Zealand examples. Tonkin (2007a, 2007b, 2007c) provided a history of soil survey and soil conservation activities in New Zealand. A quantitatively-based classification of New Zealand‟s terrestrial environments was published by Leathwick et al. (2003)

    Polynesian settlement of New Zealand and the impacts of volcanism on early Maori society: An update

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    Presents an overview of the timing of Polynesian settlement in New Zealand, discussing the application of tephrochronology and rat and avian bone dating to the problem. The impacts of volcanism on early Maori society are examined, including the catastrophic impacts of the Tarawera eruption of 1886

    Pukekohe silt loam, Pukekohe Hill

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    Pukekohe Hill is an excellent starting point for the tour in various ways: it provides a commanding view of important market gardens developed within Ultisols, and associated landuse issues, and the Massey Memorial on the hilltop commemorates Irish-born, South Auckland identity William (‘Big Bill’) Fergusson Massey (1865-1925), Prime Minister of New Zealand 1912-1925, after whom Massey University is named. Pukekohe town has a population of about 23,000

    Transactional Education and Transactional Educators: Fostering the Habit of “Using Intelligence Fully”

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    This paper calls into question the assumptions implicit in many traditional theories of moral agency; namely, the assumption that moral agency requires the agent to be disinterested, disengaged, and psychically distant in order to be a good moral agent, an agent worthy of moral praise. I explore the nature of what it means to be a moral agent and, more broadly, what it means to live well as a human being and apply this analysis to education. The arguments made are grounded in a naturalistic-transactional understanding of how the human being comes to be and continues to be in this world and spells out some of the implications of this understanding of the human individual for education. In addition, I suggest specifi c strategies for capitalizing on the transactional potential of the educational relationship between student and teacher. I argue that, if we take the human being to be a transactional being, i.e., an entity that comes into existence and continues to exist necessarily in and through co-constitutional exchanges with both human and non-human entities, then the role of education becomes central to this development of the individual. Further, it also becomes clear that education must be of a particular nature if it is going to foster the immediate and ongoing development of that individual as a fl ourishing human being. However, we must fi rst explore briefl y what is problematic about our traditional conception of education in order to see that change is required

    Revision of the age and stratigraphic relationships of Hinemaiaia Tephra and Whakatane Ash, North Island, New Zealand, using distal occurrences in organic deposits

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    The stratigraphic and chronologic relationships of Hinemaiaia Tephra and Whakatane Ash are examined using distal tephras preserved in organic-rich deposits at five sites in eastern and northern North Island, New Zealand. A c. 10mm thick, unnamed white rhyolitic ash layer described at two of the sites (Tiniroto and Poukawa), and previously of disputed stratigraphic signillcance, also occurs at the other three sites (Kaipo, Rotomanuka, and Okoroire) as a primary airfall tephra. The tephra is derived from the Taupo Volcanic Centre and is correlated with Hinemaiaia Tephra (definition of Froggatt) using similarity of stratigraphic position, composition (ferromagnesian mineralogy and glass chemistry), and radiocarbon age. It stratigraphically overlies Whakatane Ash. The tephra underlying Whakatane Ash, and previously identified as Hinemaiaia Ash (definition of Vucetich & Pullar), is probably Motutere Tephra. Hinemaiaia Tephra has a mean age of old (TÂœ) c. 4500 years, Whakatane Ash c. 4800 years. New Âč⁎C dates, obtained on peat or gyttja adjacent to these tephras, are (old T1/2, years B.P.): 4220 ± 60 (NZ316OA), 4490 ± 70 (Wk541)( above Hinemaiaia Tephra); 4470 ± 70 (Wk542) (below Hinemaiaia Tephra); 4800 ± 50 (NZ3161A), 4490 ±60 (Wk496), 4530 ± 60 (Wk497), 4260 ± 140 (Wk662) (below Hinemaiaia Tephra and above Whakatane Ash); 5210 ± 80 (NZ3162A), 4860 ±70 (Wk501), 4850 ± 80 (Wk660) (below Whakatane Ash). Based on the distal occurrences described here, the Hinemaiaia Tephra has a much more wide spread distribution than previously demonstrated, and may have been emplaced by a very powerful "above average" plinian eruption

    INTREPID Tephra-II: - 1307F

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    The INTREPID Tephra project, “Enhancing tephrochronology as a global research tool through improved fingerprinting and correlation techniques and uncertainty modelling”, was an overarching project of the international community of tephrochronologists of the International Focus Group on Tephrochronology and Volcanism (INTAV), which in turn lies under the auspices of INQUA’s Stratigraphy and Chronology Commission (SACCOM). INTREPID’s main aim has been to advance our understanding and efficacy in fingerprinting, correlating, and dating techniques, and to evaluate and quantify uncertainty in tephrochronology, and thus enhance our ability to provide the best possible linking, dating and synchronising tool for a wide range of Quaternary research projects around the world. A second aim has been to re-build the global capability of tephrochronology for future research endeavours through mentoring and encouragement of emerging researchers in the discipline

    Project 0907: INTREPID – Enhancing tephrochronology as a global research tool through improved fingerprinting and correlation techniques and uncertainty modelling

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    In May, 2010, the inter-congress meeting of the INQUA International focus group on tephrochronology and volcanism (INTAV) was held in Kirishima City, southern Kyushu, Japan. INTAV was formed in 2007 at the International Union for Quaternary Research (INQUA) congress held in Cairns. It replaced SCOTAV (Sub-commission on tephrochronology and volcanism), COT (Commission on tephrochronology), and earlier tephrarelated research groups dating back to the 1960s. Previous meetings of the group in the past two decades were held in the Yukon Territory, Canada (2005), France (1998), New Zealand (1994), and USA (1990). The venue for the 2010 meeting was the main hall of the Kokobu Civic Centre in Kirishima City, which was very generously provided free of charge by the Kirishima authorities in return partly for the delivery of two public lectures, one by David Lowe (“Connecting with our past: using tephras and archaeology to date the Polynesian settlement of Aotearoa/New Zealand”) and the other by Hiroshi Machida (“Widespread tephras originating from Kagoshima occurring in northeast Asia and adjacent seas”), on Sunday 9 May. Participants were treated to a personal welcome by the Mayor of Kirishima City, Shuji Maeda, followed by what appeared to be a very special (and delicious) banquet. However, this spread turned out to be standard lunch and dinner fare provided by the centre’s cafeteria and was enjoyed by participants throughout the meeting
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