Crystallographic and structural transformations of sedimentary chalcedony in flint upon heat treatment

The early occurrence of intentional heat treatment of silica rocks has recently become a key element in the discussion about the cultural modernity of prehistoric populations. Lithic vestiges are the only sources that remain of this process and the understanding of the material’s properties and transformations are essential for reconstructing the conditions and parameters applied during heat treatment. Several models of the structural transformations upon heating have been proposed in the current literature. These models are often contradictory and do not account for the most recent structural and mineralogical data on chalcedony. In order to propose a new model, we elaborated an experimental procedure and applied different techniques involving infrared spectroscopy, solid state NMR, X-ray diffraction and electron microscopy. The results show that the major transformation to happen is the loss of silanole (SiOH) and the creation of new Si-O-Si bonds according to the reaction: Si?OH HO-Si → Si-O-Si + H₂O. This reaction starts between 200 °C and 300 °C and causes an increase in the hardness of the rocks. The maximal annealing temperature and the ramp rate are the functions of the ability of the structure to evacuate newly created H₂O and depend on the size of the specimen and the volume of its porosity. These results also show that the annealing duration at maximum temperature can be relatively short (<50 min) for a sufficiently large amount of transformation to be accomplished.     

SOMETIMES CLOSE IS GOOD ENOUGH: THE VALUE OF NEARBY ENVIRONMENTAL AMENITIES*

ABSTRACT An extensive empirical literature exists, showing that variations in region‐specific amenities can account for persistent differences in real wages across regions. However, this literature has considered only amenities in the same location as the household. This paper argues that environmental amenities at some distance from but accessible to urban areas may lead to negative compensating wage differentials. We use a general equilibrium framework and data from the 1995 Current Population Survey to calculate implicit amenity prices based on measures of distance to environmental amenities. Our results suggest that amenities outside the metropolitan area do generate compensating wage differentials, as workers are willing to accept lower wages to live in accessible proximity to “nice” places. This implies that these places provide a positive externality to those communities that find them accessible. The estimated effects are quantitatively important, suggesting that these externalities should be taken into account in policy making.     

Detection of diffusion and contact zones of early farming in Europe from the space-time distribution of 14C dates

The spread of early farming in Europe is revisited using a sample of 3072 audited 14C calBC dates from 940 georeferenced early Neolithic sites. The surface expansion of early Neolithic has been reconstituted using the kriging technique of spatial interpolation. Centres of renewed expansion, of contact zones, and the main routes of expansion have been highlighted by means of a vector map, representing the gradient. The expansion of the agricultural system on the map, was not uniform and regular across Europe as a whole, but proceeded in leaps. With the scale of detection of the 500-year isochrones, several leaps are identifiable: at 8000 calBC crossing the Taurus barrier, 6700–6100 calBC crossing the southern Adriatic barrier, 6100–5600 calBC crossing the Central European agro-ecological barrier and 5000–4000 calBC expanding on the other, marginal zones. Using a vector map, 10 points of renewed expansion and nine contact zones, were detected. The whole does not correspond to a process of homogeneous diffusion, approximately steady, but a process marked by phases of geographical expansion and stasis.     

Considering Multiscalar Approaches to Creolization Among Enslaved Laborers at Estate Bethlehem, St. Croix, US Virgin Islands

Archaeological studies of plantations need to consider the scale of the historical circumstances which shape locally circumscribed Creole processes. These circumstances range from broad generalizations down to factors operating only at the local level of the individual estate. Recent excavations at Estate Lower Bethlehem, St. Croix, Virgin Islands, have recovered an artifact assemblage from a laborer village dating from the mid-eighteenth century to the first quarter of the nineteenth century, which was situated adjacent to a previously unrecorded cemetery and a large tamarind tree. This assemblage illustrates the importance of a multiscalar approach to Creolization in two ways: an analysis of the distribution of vessel forms of European pottery and “Afro-Cruzan” earthenwares; and the identification of fragments of lead-glazed slip-decorated redware pottery produced by Moravians.     

Teaching revolutionary archaeology: African experiments in history making and heritage management

Este ensayo se enfoca en la experiencia de estudiantes africanos intentando estudiar y lograr administrar herencia en Tanzania y eritrea. El autor ilustra la necesidad de métodos prácticos que enfatizan hacer decisiones independientes y el crecimiento de la auto-confianza personal en los contextos del desarrollo rápido y disturbios políticos. Estas perspectivas de ense?anza ofrecen una respuesta positiva de los estudiantes que ven oportunidades para realizar la arqueología de su propia herencia desde su propio punto de vista.

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Résumé Ce papier se concentre sur l'expérience d'étudiants africains qui ont étudié et tenté de mettre en oeuvre la gestion du patrimoine en Tanzanie et en Erythrée. L'auteur illustre la nécessité d'avoir des approches pratiques qui favorisent la prise de décisions indépendante et l'augmentation de la confiance personnelle, dans le cadre professionnel, dans des contextes de développements rapides et de changements politiques brusques. Cette perspective pédagogique induit une réponse positive des étudiants qui voient des opportunités de faire l'archéologie de leur propre patrimoine selon leurs propres points de vue.