Microfossil Research Ltd

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Microfossil Research Ltd

New Zealand
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Nichol S.L.,University of Auckland | Chague-Goff C.,University of New South Wales | Goff J.R.,University of New South Wales | Horrocks M.,University of Auckland | And 3 more authors.
Sedimentary Geology | Year: 2010

Chatham Island in the southwest Pacific Ocean is exposed on all sides to potential tsunami impact. In historical time, tsunamis are known to have inundated the coast on several occasions, with the largest event in 1868. Coastal dunes along the northeast coast of Chatham Island preserve sedimentary evidence of this and possibly earlier tsunami events, as localised gravel lags. However, these deposits lack a clear stratigraphic context and establishing their age is difficult. This study examines the sediment record in a freshwater wetland at Okawa Point, located directly landward of the dunes where apparent tsunami gravels occur. Sediment descriptions, pollen, foraminifera, chemical data and radiocarbon dates from cores are used to reconstruct the environmental history of the wetland. The record extends from ca >43. ka to the present and incorporates glacial, post-glacial and human-influenced phases. Throughout this time the wetland appears to have remained isolated from catastrophic marine inundation. The only evidence for saltwater intrusion is observed in the historic period, via geochemical, grain size and pollen data, which record a marine inundation event that forced the transport of a thin (cm-thick) deposit of dune and beach sand into the seaward edge of the wetland. This is interpreted as the signature of the 1868 tsunami. The lack of more widespread physical evidence for this and other tsunami events in the wetland is attributed to the morphological roughness afforded by coastal dunes and limited accommodation space for Holocene deposits. © 2010 Elsevier B.V.

Horrocks M.,Microfossil Research Ltd | Horrocks M.,University of Auckland | Nieuwoudt M.K.,University of Auckland | Kinaston R.,University of Otago | And 2 more authors.
Journal of the Royal Society of New Zealand | Year: 2014

Here we report on microfossil analysis of human dental calculus from Lapita (3000-2600 yr BP) and post-Lapita (2300-2000 yr BP) burials from Vao and Uripiv, Vanuatu. Phytoliths of introduced Musa and indigenous Heliconia in the calculus suggest the use of these taxa as food wrappings. Phytoliths and most other material in the calculus, namely sponge spicules, calcium oxalate crystals, xylem and charcoal, are unequivocal identifications. Another type of material, comprising degraded objects with a general morphology suggesting starch grains, is uncertain, however, as the unequivocal starch indicator, the Maltese cross, was not observed. We used a new method for calculus analysis, Fourier Transform InfraRed spectroscopy (FTIR), comparing the suspected starch with modern reference starch of prehistoric Pacific crops. Although the ancient FTIR analysis was limited to a small number of suspected starch grains, the results provide another line of evidence for starch. The calculus data are consistent with previous microfossil studies of Lapita deposits at the sites, and demonstrate the efficacy of this technique in contributing to the definition of the history of plant use and diet of early Pacific Island populations. © 2013 The Royal Society of New Zealand.

Feek D.T.,Massey University | Horrocks M.,Microfossil Research Ltd | Horrocks M.,University of Auckland | Baisden W.T.,Institute of Geological & Nuclear Sciences | Flenley J.,Massey University
Journal of Paleolimnology | Year: 2011

We describe an improved piston corer, the Mk II, for sampling soft sediments for ancient DNA analysis. The original Mk I model, designed to minimize contamination and successfully used in New Zealand, was subsequently deployed on Easter Island where three problems arose. Two of these problems related to sediment and water entering the core barrel and contaminating samples. The other difficulty was that plant material accumulated ahead of the piston and blocked the corer aperture. Design improvements were made to the prototype model and eliminated these problems. © 2010 Springer Science+Business Media B.V.

Horrocks M.,Microfossil Research Ltd | Horrocks M.,University of Auckland | Peterson J.,University of Guam | Carson M.T.,University of Guam
Journal of Island and Coastal Archaeology | Year: 2015

Recent advances in the study of crop fossils have been made at sites across much of the Pacific by the application of a range of microfossil techniques, namely analysis of pollen, phytoliths, and starch. Compared with Melanesia and Polynesia, however, the application of this in Micronesia is limited. Here we report on microfossil analysis of Micronesian archaeological deposits from the Mariana Islands, from two sites on Guam: Tumon and Ipan, and another near Lake Susupe, Saipan. All three sites contained subsurface deposits, dated ca. 1300–300 BP. The phytolith and starch data indicate the use of several subsistence taxa, including Musa (banana), up to three Dioscorea (yam) species, and other possible subsistence taxa, starch grains of which can be difficult to differentiate. Radiolarian fragments from the inside surface of a potsherd reflect the use of marine resources. Because plants have differential production and preservation of pollen, phytoliths, and starch, the data illustrate the value of using combined analyses of these microparts. This method also shows the combination and geographic range of crops, and that Micronesian archaeological deposits potentially contain microfossil evidence for prehistoric subsistence plants and other resources as detailed as that shown for elsewhere in the Pacific. © 2015 Taylor & Francis Group, LLC.

Abrahim G.M.S.,Geoenvironmetal Services | Parker R.J.,Geoenvironmetal Services | Horrocks M.,Microfossil Research Ltd
Estuarine, Coastal and Shelf Science | Year: 2013

Tamaki Estuary is an arm of the Hauraki Gulf situated on the eastern side of central Auckland. Over the last 100 years, Tamaki catchment has evolved from a nearly rural landscape to an urbanised and industrialised area. Pollen, 14C and glass shards analyses, were carried out on three cores collected along the estuary with the aim to reconstruct the estuary's history over the last ~8000 years and trace natural and anthropogenic effects recorded in the sediments. Glass shard analysis was used to establish key tephra time markers such as the peralkaline eruption of Mayor Island, ~6000 years BP. During the pre-Polynesian period (since at least 8000 years BP), regional vegetation was podocarp/hardwood forest dominated by Dacrydium cupressinun, Prumnopits taxifolia, and Metrosideros. Major Polynesian settler impact (commencing ~700yr BP) was associated with forest clearance as indicated by a sharp decline in forest pollen types. This coincided with an increase in bracken (Pteridium esculentum) spores and grass pollen. Continuing landscape disturbance during European settlement (commencing after 1840 AD) was accompanied by the distinctive appearance of exotic pollen taxa such as Pinus. © 2013 Elsevier Ltd.

Horrocks M.,Microfossil Research Ltd. | Horrocks M.,University of Auckland | Bedford S.,Australian National University
New Zealand Journal of Botany | Year: 2010

Analysis of deposits at a Lapita site in Vanuatu revealed putative starch grains of Dioscorea nummularia in ∼2800-3100 cal. BP layers and of Dioscorea pentaphylla in a ∼2000 cal. BP layer, suggesting local cultivation of these tuberous crops. The Dioscoreaceae are a new addition to the introduced cultigens thus far directly identified for prehistoric Vanuatu. © 2010 The Royal Society of New Zealand.

Horrocks M.,Microfossil Research Ltd | Horrocks M.,University of Auckland | Marra M.,University of Waikato | Baisden W.T.,Institute of Geological & Nuclear Sciences | And 2 more authors.
Journal of Paleolimnology | Year: 2013

A 20-m sediment core from Rano Kau, Easter Island provides plant microfossil, arthropod fossil and high-resolution 14C sampling evidence for late Quaternary environments, ant (Formicidae) distributions and human activity. The record commences prior to or during the LGM, providing the two oldest dates for Rano Kau thus far, 20,340 ± 160 and 34,260 ± 440 BP. The vegetation at the time was mostly Arecaceae (palm)-dominated grassland-woodland, suggesting cooler/drier conditions than present. Near the start of the Holocene c. 12,500 cal BP, climate alleviation is indicated by Asteraceae shrubland increasing at the expense of grassland. There is an early to mid-Holocene sediment hiatus. The record recommences c. 3,500 cal BP, with in-washed clayey soils bearing charcoal and phytoliths of Polynesian-introduced Musa (banana) and mixed with wetland detritus, reflecting slumping as a result of forest clearance and gardening. Dates of material of other plants from the clay/detritus layers containing the Musa phytoliths are older than expected, within the range 3,680-2,750 cal BP, well before settlement of Eastern Polynesia. This could reflect horticultural material settling in an older part of the sediment column or age increase by reservoir effects. A long section of overlying unconsolidated detritus provides a progressively younger upward sequence from 2,840-2,870 to 930-810 cal BP, but dates are variable after 1,290-1,180 cal BP, where charcoal, disturbance-related pollen and older than expected ant exoskeletons demonstrate the inclusion of pre-aged material from the floating vegetation mat or upslope erosion in the sediment column. Arecaceae pollen declines sharply after 930-810 cal BP. Arthropod analysis reveals two new weevil species for Easter Island, and two ant taxa, Tetramorium bicarinatum and Pheidole sp., the latter of which is also new for the island. Three of the four age determinations on ant remains suggest that ants were present prior to c. 2,500 cal BP, and probably associated with the period following the resumption of sediment accumulation c. 3,500 cal BP. Unless the apparent ant 14C ages have been increased by reservoir effects, these results question the long-accepted assumption that all Eastern Polynesia's ant species have been introduced. © 2013 Springer Science+Business Media Dordrecht.

Horrocks M.,Microfossil Research Ltd | Horrocks M.,University of Auckland | Baisden W.T.,Institute of Geological & Nuclear Sciences | Flenley J.,Massey University | Feek D.,Massey University
Journal of Paleolimnology | Year: 2012

Previous paleoenvironmental records from the lake of Rano Raraku crater, Easter Island's statue quarry, showed evidence of two major environmental changes, fluctuating lake levels and Polynesian forest clearance. There have been no reports, however, of former shorelines and it is not known if deforestation of the crater was for quarrying alone, or also for agriculture. We shed light on this by examining macrofossil casts of plants found in dryland iron pan deposits, and using combined analyses of pollen, phytoliths and starch in a lake sediment core and dryland soil profile. Casts of wetland taxa, namely Scirpus californicus and fern rhizomes, were identified in the iron pan deposits up to ~10 m above the current lake level, providing evidence of higher lake level during the last Glacial period. This height is near the level of the col on the western side of the crater, indicating that the lake was at its maximum possible elevation at the time, with overflow via the col. Microfossils of introduced Colocasiaesculenta (taro), Ipomoeabatatas (sweet potato), Musa (banana sp.) and possibly Lagenariasiceraria (bottle gourd) were identified in the core and soil profile, providing evidence of ancient Polynesian agriculture. Earliest evidence of gardening occurs at ~627-513 cal BP, immediately after large-scale forest clearance. The core and soil profile were located on opposite sides of the catchment, suggesting that the crater was intensively multi-cropped and that widespread irrigated gardens co-existed with statue-quarrying activity. © 2012 Springer Science+Business Media B.V.

Horrocks M.,Microfossil Research Ltd | Horrocks M.,University of Auckland | Baisden W.T.,Institute of Geological & Nuclear Sciences | Nieuwoudt M.K.,University of Auckland | And 2 more authors.
Journal of Paleolimnology | Year: 2012

Previous wetland vegetation records from Easter Island showing deforestation and Polynesian agriculture are limited to cores that rely on pollen, with a single cultigen pollen type identified: Urticaceae/Moraceae, possibly Broussonetiapayrifera (paper mulberry). Here we redress this by also using phytolith and starch analyses on four lake sediment cores on a ~350-m transect along the southwest edge of Rano Kau, focusing on in-washed basal clayey layers. We also use a new method, Fourier transform infrared spectroscopy, to positively identify degraded starch collected from sedimentary deposits. The cores are the first samples recovered from an area in the lake that (a) lies below the relict village of Orongo, (b) is near a section of the crater believed to be most accessible from the Pacific coast, and (c) is far from the northern crater rim and receives high solar radiation, a likely benefit for crops of tropical origin. Pollen and phytoliths are abundant in the clayey layers and sparse in overlying layers of organic lake detritus and living rhizomes. Mixing of core deposits as a result of human activity has disordered the radiocarbon sequence, precluding development of an reliable chronology. Containing microfossils of several introduced cultigens, the clayey layers represent gardened terraces that have slumped into the lake. The data indicate large-scale deforestation and a mixed-crop production system including Broussonetiapapyrifera, Colocasiaesculenta (taro), Dioscoreaalata (greater yam), Ipomoeabatatas (sweet potato), Lagenariasiceraria (bottle gourd) and Musa (banana) sp. The data show (a) the potential for using the combined analyses to provide direct evidence of Polynesian horticulture on Easter Island and (b) that the island's wetlands potentially hold extensive horticultural records. The study highlights the concept of 'transported landscapes,' whereby colonising people replace indigenous forests with artificial, imported agricultural landscapes. © 2011 Springer Science+Business Media B.V.

Allen M.S.,University of Auckland | Butler K.,Massey University | Flenley J.,Massey University | Horrocks M.,Microfossil Research Ltd
Holocene | Year: 2011

Three sediment cores, from one upland and two lowland sites on Nuku Hiva, Marquesas Islands, provide a c. 750-year record of palaeo-environmental change on the island. Accelerator mass spectrometry (AMS) dating of pollen concentrates from the base of each core indicates that the three widely separated marshes developed c. AD 1200 and 1350, after the known period of human colonisation and establishment. Detailed analyses (pollen, sediments, and charcoal) and additional dating of the upland core from Tōvi'i Plateau (810 m) allow for identification of four chronozones. The core sediment data and age-depth curve suggest an alternation of wet-dry-wet conditions over the c. 750-year period. The pollen spectra, in contrast, are fairly stable, with ferns dominating but arborescent species also present. The micro-charcoal evidence points to regional burning and long-distance transport until c. AD 1640, after which localised burning may be indicated. Among the more notable changes is a major increase in pollen and spore deposition after c. AD 1640, a trend most evident in the pollen concentration diagram. Overall, the data suggest rapid sedimentation in the fourteenth century AD, followed by drier and/or more settled conditions until the mid-seventeenth century, and finally wetter conditions after c. AD 1640. The latter in particular is consistent with emerging regional evidence for warm-wet conditions in the central eastern Pacific during the seventeenth century, the height of the Northern Hemisphere 'Little Ice Age'. The charcoal record also provides insights into human activities on the island, suggesting burning in the lowlands from the fourteenth century AD, probably in conjunction with forest clearance preparatory to tree and root crop cultivation. © The Author(s) 2011.

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