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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. Source

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. Source

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. Source

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. Source

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. Source

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