200 results for University of Waikato, Lowe, David J.

  • INTREPID Tephra-II: - 1307F

    Lowe, David J. (2013)

    Journal article
    University of Waikato

    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.

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  • Stop 2 Kainui silt loam and Naike clay, Gordonton Rd

    Lowe, David J. (2008)

    Conference item
    University of Waikato

    At this stop are several remarkable features both stratigraphic and pedological, and a “two-storied” soil, the Kainui silt loam alongside (in just a few places) the Naike clay. Both soils are Ultisols. The sequence of tephra beds and buried soil horizons spanning about 1 million years was exposed in 2007 by road works.

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  • Guidebook for Pre-conference North Island Field Trip ‘Ashes and Issues’, 28-30 November, 2008

    Lowe, David J.

    Book
    University of Waikato

    Guidebook for Pre-conference North Island, New Zealand Field Trip ‘Ashes and Issues’, 28-30 November, 2008. The route goes progressively towards the locus of the most recently active volcanic centres in central North Island. Concepts of upbuilding pedogenesis in tephra-mantled terrains will be discussed. Topical issues relating to soil and water quality and land management of intensive horticulture, pastoral farming (especially dairying), plantation forestry and C budgeting and modelling, and municipal effluent disposal by land treatment, will be considered as well. The declining quality of water in lakes in the Rotorua region and in Lake Taupo (mainly as a result of increasing N and P), and large-scale land-use conversions from plantation forestry to dairy farming in the Taupo area, and implications, are examined on days 2 and 3 of the trip.

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  • Colin George Vucetich (1918–2007)—pioneering New Zealand tephrochronologist

    Lowe, David J.; Tonkin, Philip J.; Neall, Vincent E.; Palmer, Alan S.; Alloway, Brent V.; Froggatt, Paul C. (2008)

    Journal article
    University of Waikato

    Many Quaternarists, tephrochronologists, and soil scientists mourned the passing in New Zealand of Colin Vucetich—gentle mentor, pedologist, and pioneering tephrochronologist—on 25 April (Anzac Day), 2007. Colin was in his 89th year. As well as forming a 25-year partnership with W.A. “Alan” Pullar, with whom he published three classic papers on tephrostratigraphy based on field work undertaken by the pair largely in their own time, Colin inspired and mentored numerous postgraduates in his later career as an academic at Victoria University of Wellington. There he taught pedology, soil stratigraphy, and tephrochronology until his retirement as Reader (Associate Professor) in 1982. In retirement he was an honorary lecturer and supervisor at Massey University (Palmerston North) until 1991 (Fig. 1, Fig. 2 and Fig. 3).

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  • "New Zealand Soil Classification” by A.E. Hewitt [Book review]

    Lowe, David J. (1992)

    Journal article
    University of Waikato

    The publication of `New Zealand Soil Classification' by Dr Alan Hewitt this year (Hewitt 1992a) represents a major milestone in New Zealand soil science. That it was one of the final publications of the now defunct DSIR is somehow appropriate because, as classification systems should, it provides (in a mere 133 pages) a synthesis of much of what has been learnt about the soils of New Zealand over the past 60 years or more, The new classification was officially launched at the New Zealand Society of Soil Science Conference in Rotorua on 16 November, 1992.

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  • Globalization of tephrochronology: new views from Australasia

    Lowe, David J. (2008)

    Journal article
    University of Waikato

    Tephra (or volcanic ash) studies, once confined largely to volcanic lands, have become increasingly practised in countries far removed from areas of active or recent volcanism – and Australia is no exception. At the International Union for Quaternary Research (INQUA) conference in Cairns in July/August 2007, Sarah E. Coulter (née Davies), now a postdoctoral ice-core tephrochronologist at Queen’s University Belfast, reportedthe first occurrence of an exotic tephra in Australia in a core from Lynch’s Crater, Atherton Tableland, Queensland (Figure 1). The distal tephra, manifest as a tiny concentration of glass shards, was probably derived from a Papua New Guinean eruption around 75,000–80,000 years ago (S.E. Davies et al., 2007). Its value lies in providing a precise chronostratigraphic marker that potentially allows correlation of other long palaeoenvironmental sequences over wide distances. Davies’ study is but one of a revolutionary development in tephrochronology now focused on detecting diminutive, distal tephras that are invisible in the field and referred to as cryptotephras. From the Greek word kryptein, meaning ‘to hide’ (Hunt, 1999a; Hunt and Hill, 2001; Lowe and Hunt, 2001), cryptotephras typically comprise fine-ashsized (< ~100 μm) glass shards sparsely preserved and ‘hidden’ in peats or in lake, marine or aeolian sediments, or in ice cores (Figure 2). The cryptotephra theme is continued in section III, but beforehand nomenclature associated with the term ‘tephra’, which can be confusing and which sometimes is used incorrectly, is outlined.

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  • Impact of tephra fall and environmental change: a 1000 year record from Matakana Island, Bay of Plenty, North Island, New Zealand.

    Giles, Teresa M.; Newnham, Rewi M.; Lowe, David J.; Munro, Adam J. (1999-01-01)

    Journal article
    University of Waikato

    Palynological evidence was used to determine the development of vegetation communities on Matakana Island, North Island, New Zealand, over the last 1000 radiocarbon years. The pollen record indicates that changes occurred in the vegetation immediately following fallout deposition of the Kaharoa Tephra approximately 100 km from source at c. 665 years BP. Such changes may be a direct response to the impact of tephra fall, although the possibility of anthropogenic disturbance cannot be discounted. As a result of the eruption some taxa (Leucopogon fasciculatus and Tupeia antarctica) became at least temporarily extinct from the area. Two phases of anthropogenic influence on the environment are recorded in the pollen record: Polynesian, followed by European inhabitation of the island, giving a detailed history of human influence in the area for the millennium.

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  • Andisols of New Zealand and Australia.

    Lowe, David J.; Palmer, David John (2005-01-01)

    Journal article
    University of Waikato

    During the Quaternary, much of central North Island, New Zealand, was repeatedly overwhelmed or modified by emplacement of ignimbrites and especially by multiple rhyolitic and andesitic tephra fallout deposits, and reworked derivatives, that successively mantled landsurfaces forming buried paleosols in multisequal profiles. Relatively thick proximal deposits buried and isolated antecedent soils, forming compound soil profiles, whereas relatively thin tephra fallout at medial and distal sites resulted in composite or aggrading profiles, their character determined by the interplay of upbuilding and topdown pedogenesis. Scoriaceous basaltic tephras erupted in northern North Island were locally distributed. Andisols, of the 'allophanic' type with andic soil properties dominated by short-range-order (SRO) clays rather than Al-humus complexes, cover ~32, 100 km² and comprise about 12.5% of New Zealand soils. They consist of three groups : (1) 'Entic' Udands or Cryands occur on mainly andesitic eruptives (Tephric Recent Soils in New Zealand Soil Classification ; ~1200 km² , ~0.5%) ; (2) Vitrands occur in central-eastern North Island on glassy, rhyolitic pumiceous deposits mainly from the Taupo eruption c. 232 AD and the Kaharoa eruption c. 1314 AD (Pumice Soils ; ~17, 200 km² , ~6.5%) ; and (3) Udands occur typically on composite, multiple tephra deposits of varying ages in Taranaki (mainly andesitic tephras), King Country-western Waikato (mixed andesitic-rhyolitic), eastern Waikato-western Bay of Plenty-Coromandel (mainly rhyolitic), and Auckland-Northland (basaltic), the age span of sola increasing towards distal sites as constituent tephra layers become thinner and shallower (Allophanic Soils ; ~13, 700 km² , ~5.5%). Moisture and temperature regimes are mainly udic and mesic, thermic, or cryic. Udands are pre-eminent among New Zealand's most versatile, high-quality soils because they provide valuable soil ecosystem services including sorption, water storage and supply, natural fertility, and foundation support. Andisols are currently known only in the Mt Gambier area of southeast South Australia, and comprise ~85 km² (~0.001%) of Australian soils. Intraplate basaltic volcanoes at Mts Gambier and Schank erupted c. 5000 years ago and the resultant localised tephras contain both exotic crystalline material, derived from underlying limestone and calcareous dunes, and juvenile basaltic material. Sand fractions at Mt Gambier are dominated by exotic, silicic crystalline material (≥80%) and relatively little glass (<20%) but at Mt Schank unaltered Al-rich glass predominates (≥50%). Vitrixerands and Haploxerands with pHs 6.4-8.0 have been formed under xeric moisture and mesic temperature regimes (Andic, Chernic Tenosols in Australian Soil Classification). The parent mineralogies have influenced clay mineral formation : SRO clays at Mt Schank (up to 20% allophane, 7% ferrihydrite, fine-earth basis) are more abundant than at Mt Gambier (≤12% allophane, 4% ferrihydrite) because the glass at Mt Schank weathers more rapidly than the Al-poor crystalline material at Mt Gambier, releasing Al. Seasonal Si-leaching has also been influential: where leaching is sufficient to remove silica, and CaCO3 content is low (in upper soil horizons at Mt Gambier; in most horizons at Mt Schank), Al-rich allophane has formed ; where leaching is weak (intermediate horizons), Si-rich allophane and layer silicate minerals (but not halloysite) have formed; and where leaching barely occurs (in lowest horizons), smectite has formed. The Xerands are versatile soils.

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  • Age of the Rotoehu Ash. Comment.

    Lowe, David J.; Hogg, Alan G. (1995)

    Journal article
    University of Waikato

    Suggests that the article by Whitehead & Ditchburn (1994), although presenting useful new data on 230Th/232Th analyses, is flawed and misleading in suggesting that the Rotoiti Tephra is considerably younger than c. 50 ka.

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  • Towards rapid assay of cryptotephra in peat cores: review and evaluation of selected methods

    Gehrels, Maria J.; Newnham, Rewi M.; Lowe, David J.; Wynne, Shirley; Hazell, Zoë J.; Caseldine, Chris (2008-02)

    Journal article
    University of Waikato

    Peat bogs are highly effective archives for the preservation and detection of cryptotephra but the conventional methods used to detect these hidden, diminutive layers are destructive and can be time consuming. We briefly review methods that have been used for cryptotephra detection and evaluate the potential of a range of alternative reconnaissance methods, both non-destructive and destructive, to provide for more rapid examination of continuous cryptotephra content in peat cores. The techniques evaluated—magnetic susceptibility (MS), spectrophotometry, and X-ray fluorescence—are used to pick out compositional contrasts between tephra deposits and peat. Measurements of organic content are also evaluated as a potential guide to tephra content based on an inverse relationship. Although we find limitations to each method, particularly where deployed at the distal-most end of tephra dispersal, there is potential for all methods to be used in the detection of cryptotephra where time or material is limited. These methods can also provide additional sedimentological and stratigraphic information for studies of peat cores. However, where a reliable cryptotephra profile is required, we conclude that there is no quick or easy substitute for the conventional extraction-microscopy method.

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  • A late-Holocene and prehistoric record of environmental change from Lake Waikaremoana, New Zealand

    Newnham, Rewi M.; Lowe, David J.; Matthews, Brent W. (1998)

    Journal article
    University of Waikato

    Further evidence in support of a late pre-European (Polynesian) settlement of New Zealand is provided by an 1850-year-long tephropalynological record from a remote region in New Zealand's North Island. The earliest unequivocally anthropogenic forest clearance is estimated from sedimentation rates to have occurred c. 375 14C years BP (c. ad 1523–1631), although the radiocarbon chronology, shown by tephrochron ology to be erroneous due to hard-water effects, suggested this occurred c. 900 years earlier. Delineation of the anthropogenic era, and the distinction between human activity and other agents of environmental change in the pollen/spore diagram, are supported by cluster analysis and detrended correspondence analysis. Two distinct phases of forest clearance are evident during the pre-European era, reflecting local changes either in population pressure or settlement patterns. We note that the lull between the two phases of forest clearance coincides with the maximum of the ‘Little Ice Age’ within the period c. late ad 1600s to early 1800s.

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  • Late Quaternary volcanism in New Zealand: Towards an integrated record using distal airfall tephras in lakes and bogs

    Lowe, David J. (1988)

    Journal article
    University of Waikato

    Studies on distal airfall tephra layers preserved in lake sediments and peats in northern New Zealand have documented the stratigraphic, chronologic, and compositional relationships of 46 eruptives, aged c. 17000–700yr BP, which originated from six North Island volcanic centres: Taupo (9 tephras), Okataina (8), Maroa (1) (rhyolitic); Mayor Island (2) (peralkaline); Tongariro (11), Egmont (15) (andesitic). Sources were distinguished by mineralogy and composition, field relations, and 14C chronology. All known rhyolitic tephra-producing eruptions from Taupo, Okataina, and Maroa volcanoes since c. 17000yr BP are represented, but only a small proportion of the known tephras erupted from Tongariro, Egmont, or Mayor Island volcanoes is recorded. The distal tephras from these latter volcanic centres may thus reflect atypically powerful (or oblique) eruptions, or dispersal by strong winds. An improved record of volcanism for the Tongariro, Egmont, and Mayor Island centres might be obtainable from suitable lakes or bogs more proximal to them.

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  • Application of new technology liquid scintillation spectrometry to radiocarbon dating of tephra deposits, New Zealand

    Lowe, David J.; Hogg, Alan G. (1992)

    Journal article
    University of Waikato

    Two major technological advances in the radiocarbon dating method have recently enhanced its potential application to tephra studies: the advent of accelerator mass spectrometry and the development of new technology liquid scintillation (LS) spectrometry. The new technology LS spectrometer represents a significant refinement of the conventional dating method based on liquid scintillation counting of benzene. It improves upon conventional LS counting by allowing spectral analysis, and by providing a high degree of counting stability and efficiency in an ultra low-level background radiation environment. These attributes enable radiocarbon dating with greater accuracy and statistical precision, and also allow the determination of both smaller and older samples than previously possible by conventional radiometric methods. The new Wallac Oy ‘Quantulus’ LS spectrometer has been in operation at the University of Waikato Radiocarbon Dating Laboratory since 1988. The instrument achieves ultra-low background levels by both passive and active forms of shielding. The shielding comprises a massive asymmetric passive lead shield surrounding an aticoincident liquid scintillation guard. In addition, the Quantulus contains dual multichannel analyzers which allow spectral analysis and ‘windowless’ data acquisition. The Quantulus LS spectrometers at the Waikato laboratory have been used to date a variety of carbonaceous materials associated with tephra deposits in New Zealand, ranging in age from ca. 0.1–55 ka. In particular, we have tested the capability of the Quantulus for determining ages of samples that are typically more difficult or impossible to date by conventional methods: (1) very young samples (e.g. Tarawera Tephra, erupted ca. 100 years ago); (2) older samples (e.g. Mangaone Tephra, erupted ca. 30 ka); and (3) samples containing only sparse carbon (e.g. lake sediments associated with tephra layers aged ca. 20 ka or less). The Quantulus LS spectrometer is both more accurate and precise (statistical counting errors are reduced) than conventional instruments, is capable of extending the limits of detection at both ends of the age scale, and has a smaller sample handling ability. Analyses can be obtained at comparatively low cost. Such advances are potentially beneficial to tephrochronology and volcanology and a wide range of applications in Quaternary research.

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  • Holocene vegetation and volcanic activity, Auckland Isthmus, New Zealand

    Newnham, Rewi M.; Lowe, David J. (1991)

    Journal article
    University of Waikato

    A 12 000 to 4000 yr BP pollen and tephra-bearing profile from Auckland, New Zealand, provides insights into the vegetation history and evidence for early Holocene volcanic activity in this area centred on the Mount Wellington basaltic volcano. Possibly 500 yr separated initial scoriaceous ash deposition (ca. 9500 yr ago) and subsequent major lava flows (ca. 9000 yr ago) from Mount Wellington. The local vegelation, topography, and drainage patterns were substantially modified during this time, and damming by the lava flows resulted in the formation of Lake Waiatarua in a shallow valley head ca. 9000 yr ago. Diatom evidence indicates that this lake was initially deep (> 5 m) but was shallowing around 4000 yr ago. In contrast to the Mount Wellington eruptions, tephra deposition resulting from distant rhyolitic volcanic activity of the central North Island and Mayor Island has had little effect on the Auckland vegetation during this time interval (12 000–4000 yr ago). Between ca. 12 000 and 10 000 yr ago, conifer-angiosperm forest was the predominant vegetation cover on Auckland Isthmus, but during the early Holocene, forest dominated by Metrosideros expanded, probably on to fresh volcanic surfaces resulting from the Mount Wellington eruptions. At this time, swamp forest communities developed in Waiatarua valley basin, and included species indicative of moist, mild, relatively frost-free climates. Some taxa show histories consistent with other records from the northern New Zealand region, including the rise of Ascarina lucida ca. 11 000 to 9000 yr ago, and its subsequent decline, and the expansion of Agathis australis (kauri) forest communities from ca. 6000 yr ago. Taken together the history of local and regional vegetation points to a mild, moist and weakly seasonal early Holocene climate, which subsequently became drier with greater seasonal temperature extremes.

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  • Tephras and New Zealand archaeology

    Lowe, David J.; Newnham, Rewi M.; McFadgen, Bruce G.; Higham, Thomas F.G. (2000)

    Journal article
    University of Waikato

    Establishing an accurate date for earliest Polynesian settlement in New Zealand is essential for understanding patterns of settlement and associated environmental impacts, and the processes and rates of cultural change in Eastern Polynesia. Tephra deposits from five volcanic centres, together with exotic sea-rafted pumice, provide isochronous constraints on the timing of earliest settlement and human impacts in northern New Zealand. A local basaltic tephra from Rangitoto Island (Auckland) and locally distributed andesitic tephras from Egmont volcano directly date human occupation to c. AD 1400–1450. Distal andesitic tephras (Tufa Trig Formation) from Mt Ruapehu, Tongariro volcanic centre, help constrain the timing of earliest anthropogenic deforestation signals in Hawke's Bay. Sea-rafted Loisels Pumice(s), although of uncertain stratigraphic reliability in places, overlies cultural remains that can be no younger than c. AD 1350 along the east coast, North Island. The regionally extensive rhyolitic Kaharoa Tephra, which erupted from Okataina volcano between c. AD 1300–1390, is the critical “settlement layer” datum for dating prehistory in the North Island: no human artefacts are recorded beneath it and the earliest inferred environmental impacts by humans are dated to c. AD 1280, just prior to its deposition. This maximum date matches the earliest radiocarbon dates derived for both settlement and human impacts from archaeological and natural sites (c. AD 1250), and implies that the onset of deforestation was essentially contemporaneous with initial settlement. The widespread rhyolitic Taupo Tephra, which erupted from Taupo volcano c. AD 200, provides an isochronous benchmark well before earliest settlement. The tephra may coincide approximately with a putative earlier transient contact in New Zealand based on Pacific rat-bone (Rattus exulans) dates. More precise calendrical dates on the tephras—via dendrochronology or ice-core records or other dating methods—would help refine assessment of the timing of earliest settlement, while extending the distributional range of critical tephra layers, through application of crypto-tephra analysis, could lead to a greater understanding of settlement patterns.

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  • Quaternary environmental change in New Zealand: a review

    Newnham, Rewi M.; Lowe, David J.; Williams, Paul W. (1999)

    Journal article
    University of Waikato

    The discovery that orbital variations are the driving force behind Quaternary climate change provides an impetus to set local and regional records of environmental change into the global context, a principle that has been strongly embraced by Quaternary scientists working in New Zealand. Their major achievements and significant current initiatives are reviewed here. The importance of the New Zealand Quaternary stems from its geographical context: a climatically sensitive, remote oceanic, southern location spanning 17 degrees of the mid-latitudes; an obliquely convergent plate boundary setting resulting in a high mountain range athwart the prevailing westerlies, active volcanism, a youthful and dynamic landscape, and mountains high enough to maintain glaciers today; and a remarkably short prehistory. The resultant records show marked environmental changes due not only to climatic oscillations but also to vigorous, active tectonism and volcanism. The Taupo Volcanic Zone, containing the world's strongest concentration of youthful rhyolitic volcanoes, has produced at least 10 000 km3 of magma in the last 2 Ma. Climatic interpretations of records from marine sediments in the New Zealand region, together with several long sequences of alternating marine and terrestrial sediments, indicate broad synchrony with Northern Hemisphere events (within limitations of dating), although there are differences in detail for shorter-term climatic events. It is not yet certain that glacial advances coincided precisely with those in the Northern Hemisphere or were of similar duration. Late Cainozoic glaciation commenced c. 2.6-2.4 Ma but the record of glacial deposits is fragmentary and poorly dated except for the most recent events. The Last (Otira) Glaciation, from c. 100-10 ka, was characterized by at least five glacial advances including during the Last Glacial Maximum from 25 to 15 ka, when snowlines fell by 600-800 m. New Zealand evidence for cooling during the Younger Dryas stade is equivocal whilst isotopic records from speleothems, and other data, indicate warmer and wetter conditions from 10-7 ka, broadly conforming with records from mid-latitude Northern Hemisphere locations. Future advances will require sampling at shorter timescales, improvements in the accuracy and precision of existing dating methods and the development of new ones, extension of palaeoecological techniques to cover the full potential of New Zealand's diverse biota, and a stronger emphasis on quantification of palaeoclimatic parameters.

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  • Impacts of deforestation and burning, and the role of bracken fern, on the properties of surficial or buried soil A-horizons

    Lowe, David J.; McDaniel, Paul (2008)

    Conference item
    University of Waikato

    Bracken fern (Pteridium spp.) is an aggressive plant that commonly invades disturbed sites. Its success as an invader is attributable, in part, to its ability to produce abundant growth, both below ground in the form of rhizomes and fine roots and above ground as fronds and stems. This biomass production has been shown to affect numerous soil properties. In describing soils of the „Pumice Lands‟ (Pumice Soils or Vitrands mainly) in New Zealand, Molloy and Christie (1998) attributed black A horizons „to bracken fern, which replaced much of the forest‟. Analyses of humus and phytoliths in the A horizons of soils developed especially on Kaharoa and Taupo tephras in central North Island (buried beneath 1886 Tarawera eruptives in the Rerewhakaaitu area) showed that type-A humic acids predominated and that fernland and grassland had replaced the pre-existing forests (Birrell et al., 1971; Sase et al., 1988; Hosono et al., 1991; Sase and Hosono, 1996). Pollen, phytolith and associated studies, together with tephrochronology, have shown that human-induced deforestation by burning began in New Zealand soon after Polynesian settlers arrived (e.g. McGlone, 1989; Clarkson et al., 1992; Kondo et al., 1994; McGlone et al., 1994; Newnham et al., 1998; McGlone and Wilmshurst, 1999; Watanabe and Sakagami, 1999; see also article on Polynesian settlement by Lowe, this volume). The repeated burning resulted in the formation of extensive fernlands (McGlone et al., 2005).

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  • Old bones tell new tales

    Lowe, David J. (2006)

    Journal article
    University of Waikato

    Of all the so-called evidence that has been presented in support of human settlement in New Zealand before the second millennium, only a set of radiocarbon-dated rat bones has appeared scientifically credible. Now even that is coming under close scrutiny.

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  • Distal occurrence of mid-Holocene Whakatane Tephra on the Chatham Islands, New Zealand, and potential for cryptotephra studies

    Holt, Katherine A.; Lowe, David J.; Hogg, Alan G.; Wallace, R. Clel (2011)

    Journal article
    University of Waikato

    The Whakatane Tephra, a rhyolitic tephra erupted ca. 5500 cal. BP from Okataina Volcanic Centre, central North Island, has been identified on the Chatham Islands which lie ˜900 km east of Christchurch, New Zealand. The visible tephra layer, ˜5 mm in thickness and preserved within peat on Pitt Island, was identified using both radiocarbon dating and analysis of glass shards by electron microprobe. Whakatane Tephra is the first Holocene tephra to be identified on the Chatham Islands, and it is the most distal Holocene tephra yet recorded in the New Zealand region, being ˜850 km from source. The Pitt Island occurrence extends the tephra's dispersal area markedly, by an order of magnitude, possibly to ˜300,000 km2. An estimated dispersal index (D) of approximately 105 km2 indicates that the eruption generated a very high plinian column, possibly exceeding ˜30 km in height, with strong winds blowing the ash plume southeastwards. This new discovery of distal Whakatane Tephra as a thin but visible layer strongly implies that cryptotephras are likely to be preserved on the Chatham Islands and within adjacent ocean floor sediments. Therefore the potential exists to develop enhanced cryptotephrostratigraphic records from these distal areas, which in turn would help facilitate precise correlation via tephrochronology of palaeoenvironmental records (such as NZ-INTIMATE) from mainland New Zealand, the southwest Pacific Ocean, and the Chatham Islands.

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  • Stratigraphy and chronology of the Stent tephra, a c. 4000 year old distal silicic tephra from Taupo Volcanic Centre, New Zealand.

    Alloway, Brent V.; Lowe, David J.; Chan, R.P.K.; Eden, Dennis N.; Froggatt, Paul C. (1994-03-01)

    Journal article
    University of Waikato

    Tephrostratigraphic and chronologic studies in two areas of the North Island have identified a previously unrecorded, thin, distal silicic tephra derived from the Taupo Volcanic Centre. In Taranaki, three radiocarbon ages of the uncorrelated tephra are consistent with the independent radiocarbon chronology obtained from enveloping Egmontsourced tephras. In western Bay of Plenty, where the uncorrelated tephra is also directly dated, it is overlain by Whakaipo Tephra (c. 2.7 ka) and underlain by Hinemaiaia Tephra (c. 4.5 ka). From these sites in Taranaki and western Bay of Plenty, seven radiocarbon dates obtained on the uncorrelated silicic tephra yield an error-weighted mean age of 3970 ±31 conventional radiocarbon years B.P. The ages on the uncorrelated tephra (informally referred to as Stent tephra) from both areas are statistically identical but significantly different from those on both Waimihia and Hinemaiaia Tephras. occurrence of Stent tephra in Taranaki, c. 160 km upwind from the postulated source area, and in western Bay of Plenty, suggests that it represents the product of a moderately large plinian eruption. Until recently, its validity as a discrete eruptive event had been problematical, because a near-source equivalent deposit between Waimihia and Hinemaiaia Tephras was not recognised in the Taupo area. However, a revised stratigraphy proposed by C. J. N. Wilson in 1993 for eastern sectors of the Taupo area shows that multiple tephra layers were erupted from Taupo volcano between c. 3.9 and 5.2 ka. Of these newly recognised layers, unit-g--the product of a moderately large eruption (>0.15 km3) at c. 4.0 ka--is tentatively correlated with Stent tephra. Other eruptive units recognised by Wilson are either too old or too small in volume to be considered as likely correlatives.

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