Obsidian source characterization in the Cordillera Real and eastern piedmont of the north Ecuadorian Andes

Recent research in the Quijos and Cosanga valleys of the eastern piedmont of Ecuador’s Cordillera Real has revealed and substantiated previous knowledge of obsidian sources that are unrelated to obsidian flow systems in the Sierra de Guamaní, Ecuador. Neutron Activation Analysis (NAA) and X-ray Fluorescence (XRF) were carried out on 47 obsidian source samples collected from several contexts in and adjacent to the study area. From samples within the study area three distinct obsidians were characterized: Cosanga A, Cosanga B, and Bermejo. These obsidians originate from a number of obsidian-bearing rhyolitic domes recently identified in the hills west of the Río Cosanga. Extensive survey of these dome localities has identified obsidian cobbles large enough for formal and informal tool manufacture. Beyond the study area, samples were collected and analyzed from the El Tablón source in the Sierra de Guamaní, providing much needed data on this poorly understood source. In addition, a sample from the newly identified Conda Dome source, near the Cotopaxi volcano, was characterized with XRF. All samples were then compared to 57 pre-existing samples from the Mullumica–Callejones, Yanaurco–Quiscatola and Carboncillo sources in the Ecuadoran Cordillera Real, as well as to artifacts from the Sumaco area in the Ecuadorian Amazon. Results of the elemental characterization indicate that the Cosanga Valley, El Tablón and Conda Dome obsidians are chemically distinct. Further, visual characteristics of Cosanga Valley obsidian types are useful in source attribution for the large artifact samples from the region. Finally, obsidian collected from the El Tablón flow suggests that this source may have produced obsidian suitable for tool manufacture.     

Excavations at Tilbury Fort,Essex

Tilbury Fort is situated on the N. bank of the Thames 25 miles doumstream from London (TQ 651 754) (FIG. 1). It is the best preserved example of late 17th-century military engineering in England and has been in guardianship since 1950. Plans by the Department of the Environment to alter the visitor access to the site from the riverfront to the landward approach necessitated excavations to establish the original construction of the earthworks, redan and ravelin and to identify the routes and levels of the roadways. Excavations were undertaken in 1973 by Jerry Pratt, concentrating on the ravelin, and in 1980 by the Passmore Edwards Museum. The results of both excavations are presented in this report.     

Investigation of the ‘canopy effect’ in the isotope ecology of temperate woodlands

Anomalously ¹³C-depleted carbon stable isotope values from closed forest ecosystems have been termed the ‘canopy effect’. Originally this was ascribed to recycling of depleted carbon from forest floor decomposition of organic material, although others have suggested that it is equally likely to be due to variations in leaf-level processes in response to increased shade. This depletion in the heavier carbon isotope is passed on to woodland herbivores feeding within the forest environments. A similar isotopic depletion has also been reported in the archaeological literature from more open temperate woodland settings, but no measurements have been made on the plants at the base of the food chain in order to quantify the effect. In this study we attempt this by examining the carbon and nitrogen stable isotopic values of different species of grasses from a range of open to closed habitat settings within Wytham Wood, Oxfordshire, UK. We find a strong relationship between carbon isotopic depletion of plant tissue and lowered light intensity with an up to 5‰ shift between grass grown in open and closed locations. In order to follow this up the food chain, we also report data on wool from sheep grazing in open pastures near the Wood, and on fallow deer living within the woodland, but which turn out not to show a strong canopy effect, probably related to their feeding strategies. We conclude that there is indeed a strong ‘canopy effect’ in temperate woodland, probably related to differential light levels, but that not all apparently woodland-dwelling mammals show such an effect. We also show considerable isotopic variation at the base of the food chain, which should counsel caution when attempting to interpret dietary isotopes using mixing models.     

Paleoenvironmental reconstruction at Canyon del Muerto,Arizona, based on principal-component analysis

A multivariate statistical technique, principal-component analysis, is used to interpret pollen assemblages from archaeological context in terms of paleoenvironmental information. The pollen samples originate from an archaeological site in northeastern Arizona (Canyon del Muerto) covering the period between AD 700 and AD 1300. Through the use of principal-component analysis the percentage constraint in the pollen counts is removed and the data set effectively reduced to groups of co-varying taxa. Once these groups are ecologically defined as to the environment they represent, their changes of dominance through time can be analysed. This study has shown a correlation between a population expansion in Canyon del Muerto (AD 1050–1150) and the dominance of upland forest types suggesting slightly cooler and/or wetter conditions. The pollen data compare well with the tree-ring indices for this region. Local disturbance is reflected in the record during the period of greatest population. A shift to a shrubland vegetation during the peak construction phase indicates the clearing of cottonwood, fir, spruce and pine (all found within the site) by local inhabitants. Thus, the palynological evidence suggests both cultural and climatic factors are involved in the explanation of pollen deposition.     

Fantastic topographies: neo-liberal responses to Aboriginal land claims in British Columbia

This paper presents an analysis of the referendum on Native land claims that took place in British Columbia (BC) in the spring of 2002. The province's Liberal Government claimed that the referendum was needed in order to secure a public mandate for a set of negotiating principles that would breath new life into the supposedly stalled treaty process. Drawing evidence from government press releases, politicians' statements and media coverage, we argue that the BC Government and its supporters employed a discourse centred on neo-liberal economic logic in order to justify the exercise. Furthermore, we charge that this discourse relies on an erasure of the historical–geographical contexts of Native–newcomer relations in the province. By drawing on Cindi Katz's socio-spatial metaphor of 'topographies', we suggest that Native space in British Columbia needs to be understood as a series of situated and grounded experiences of colonialism and capitalist production. Then, extending the metaphor, we highlight the ways in which the referendum supporters' rhetoric contains a vision of future topographies of Native experience that adhere to the private property ethic of neo-liberal economics. We conclude that the politics surrounding the treaty process must be understood as a contest over the terms of Aboriginal citizenship and not merely as a conflict over the allotment of land and resources.