Figure 1. Location of Elletts Mt.. Spatial Interactions and Communications: A Geochemical Analysis of Obsidian from the Auckland Region Brendan Kneebone. School of Social Sciences, University of Auckland. Contact: bkne002@aucklanduni.ac.nz Elletts Mountain INTRODUCTION RESULTS DISCUSSION AND CONCLUSIONS This research used portable X-Ray Fluorescence (pXRF) to geochemically assign a previously unanalysed New Zealand obsidian assemblage from Elletts Mountain (Mangataketake) in the Auckland (Tamaki) region to its geological source. X-Ray Fluorescence (XRF) is a means to record the chemical composition of rocks by producing a list of the concentrations of elements and trace elements found in different rock types. In New Zealand, this method has become very useful in obsidian studies. When a distinctive lithic material is found to be widely distributed, archaeologists can attempt to infer the social communications, means of transport, and spatial interactions which have resulted in the archaeological pattern. Initial Sourcing. Table 2: Initial colour discrimination Geochemical Sourcing and Technical Analysis. Figure 3: Geochemical sourcing results. Results of the technological analysis indicated there was no hierarchy of obsidian source based on the performance characteristics of the material and the ability to manufacture artefacts. Figure 4: Source reference location and number of samples used. The analysis completed on 316 pieces of obsidian from Elletts Mountain contributes further to the hypothesis that pre-European people in the Tamaki region were likely highly mobile, and had communication networks spanning large geographical areas. The results show that there is very little variation among the size and physical attributes of Mayor Island and Great Barrier obsidian suggesting both sources may have been used in similar ways. The data obtained from this analysis (figs. 2 and 3) show that both Mayor Island and Great Barrier Island were important sources of obsidian to the people of Maungataketake. Wider research into obsidian use in the Auckland region suggest that a decline in Mayor Island obsidian coincides with a rise in Great Barrier material, and that these two sources dominate assemblages during different temporal periods. The temporal range of occupation at Maungataketake (ca. 1400-1800AD), coupled with the near 50/50 split of obsidian material between Mayor Island and Te Ahumata indicate it is likely that Maungataketake supports this emerging pattern of obsidian use. Unfortunately, more information is required in order to confidently associate the obsidian to the dates from the site to confirm this prediction. Figure 5: Mayor Island obsidian pieces Prior to its removal by quarrying, Elletts Mountain (Maungataketake) was one of the smallest volcanic cones in the Auckland region. It was situated on a broad, low-lying peninsular jutting into the Manukau Harbour around 3km north-west of the Auckland International airport. Maungataketake, classified as a terraced Pa (NZAA site R11/31 [N42/23]) was the last fully intact surviving volcanic cone in the Auckland region (Fig 1). It had the additional feature of having relatively undeveloped lower slopes and surrounding flats, with the western side running right down to the harbours edge. At the time of excavation Maungataketake was still in a rural setting and well preserved. Elletts Mountain (Maungataketake) was excavated over three seasons during the 1970’s and early 1980’s under the directorship of Jim McKinlay (fig.2). MATERIALS AND METHODS Initial visual sourcing characterization and metric measurements Table 1: Obsidian measurements taken. Geochemical Characterisation 316 samples were large enough to be geochemically analysed using portable X-Ray Fluorescence (pXRF). All obsidian flakes 10mm by 8mm or larger from the assemblage were geochemically analysed using pXRF. Figure 2: Areas excavated at Elletts Mt. REFERENCES Lawlor, I. 2016. Ancient Lifeways of Tāmaki: a case study from Maungataketake-Elletts Mountain. Poster presented to the NZAA 2016 Conference by the Maungataketake-Elletts Mt Ancient Lifeways project Management Team and Research Manager. Moore, P. R. n.d. [1988]. Physical Characteristics of New Zealand Obsidians and their Uses in Archaeological Sourcing Studies. Unpublished Manuscript. The line spacing is set to add one-half of a line height after each entry. Select ‘Format, Line Spacing’ to adjust this setting. Philipps, R. S., A. J. McAlister, & M. S. Allen. 2016. Occupation duration and mobility in New Zealand prehistory: Insights from geochemical and technological analyses of an early Māori stone artefact assemblage. Journal of Anthropological Archaeology, 42, 105-121. Sheppard, P. J. 2004. Moving Stones: Comments on the Archaeology of Spatial Interaction in New Zealand. In. L. Furey & S. Holdaway (eds.) Change Through Time: 50 Years of New Zealand Archaeology. New Zealand Archaeological Association, pp. 147-168. Sheppard, P. J., G. J. Irwin, S. C. Lin, & C. P. McCaffrey. 2011. Characterization of New Zealand obsidian using PXRF. Journal of Archaeological Science, 38(1), 45-56. Figure 1. Location of Elletts Mt.. Auckland, New Zealand