Site Identification and Correlation Using Geoarchaeological Methods at the Cabeço do Porto Marinho (CPM) Locality, Rio Maior, Portugal

Several geoarchaeological techniques have been employed in evaluating an open-air site within a uniform sand matrix, near Rio Maior, Portugal. Electrical resistivity data, acquired at the Upper Palaeolithic site complex of Cabeço do Porto Marinho (CPM), delineated an important new occupational locus. This result was confirmed, first by auger testing which recovered subsurface artefacts, and then by direct excavation. In addition, 107 samples were recovered at the site for magnetic susceptibility measurements. Comparisons between magnetic susceptibility profiles from two loci, including the new area at CPM, show distinctive patterns which allow direct correlation between the occupation areas. These methods provide quick and inexpensive means for investigators to evaluate new sites or to correlate between and within sites, without resorting to other more time-consuming and expensive techniques.     

Town and countryside in northeastern Catalonia, 1267–c. 1450: the sobreposats de la horta of Perpignan

The study of the relationship between town and countryside in medieval Catalonia is still in an early stage. This article examines how Perpignan, the second most populous Catalonian town by the second half of the fourteenth century, extended its influence over the countryside of northeastern Catalonia through the sobreposats de la horta. Although they were the heads of the guild of Perpignan's agricultural labourers, the sobreposats de la horta acquired a broad jurisdiction over cases involving damage to property, and thus became responsible for protecting the rural interests of Perpignan's citizens more generally. First mentioned in 1339, the sobreposats de la horta continually encountered seigniorial and other opposition, but their powers steadily increased between their initial appearance and the 1380s, as did the control of Perpignan's consuls over them. However, the very success of the sobreposats de la horta necessitated a series of reforms, largely the work of Perpignan's consuls, from the 1380s onwards. These reforms attempted to restore the earlier efficiency of the sobreposats de la horta, to eliminate abuses of office, and even to limit the power of the sobreposats de la horta, whose growth the consuls had done so much to foster previously.     

Thermal waters of ‘tectonic origin’: the alkaline,Na‐HCO3 waters of the Rio Valdez geothermal area (Isla Grande de Tierra del Fuego,Argentina)

The geothermal area of Rio Valdez is located in the central portion of the Isla Grande de Tierra del Fuego (South Argentina), ten kilometers south of the southeastern sector of the Fagnano Lake. It consists of a series of thermal springs with low discharge rates (≤1 L/s) and temperatures in the range of 20–33°C distributed in an area of <1 km². The thermal springs are characterized by alkaline, Na‐HCO₃ waters with low salinity (0.53÷0.58 g/L), but relatively high fluoride contents (up to 19.4 mg/L). Their composition is the result of a slow circulation at depth, possibly through deep tectonic discontinuities connected with the Magallanes‐Fagnano Fault (MFF) system. According to geothermometric calculations, thermal waters reach temperatures in the range of 100–150°C and an almost complete chemical equilibrium with the alkali‐feldspars in the metavolcanic country rocks. The relatively high fluorine contents can be explained by the slow ascent and cooling of deep groundwaters followed by a progressive re‐equilibration with F‐bearing, hydrated Mg‐silicates, such as chlorite, which has been recognized as an abundant mineral in the metavolcanics of the Lemaire Formation and metapelites and metagraywackes of the Yahgán Formation. Finally, the isotopic composition of the investigated samples is consistent with the infiltration from local snow melting at altitudes in the range of 610–770 m asl. The comparison of our data with those collected in 1991 seems to suggest a possible progressive decline of the bulk thermal output in the near future. This possibility should be seriously considered before planning a potentially onerous exploitation of the resource. Presently, the only ways to exploit this geothermal resource by the population scattered in the area are the direct use of thermal waters and/or spa structures.     

Stable oxygen (δO) and hydrogen (δD) isotopes in ovicaprid dentinal collagen record seasonal variation

Understanding paleoenvironmental conditions, including the frequency and amplitude of seasonal variation, is crucial to understanding a wide array of human behaviors in prehistory. In vertebrate calcified tissue, inorganic oxygen isotopes derived from apatite have been widely used as a proxy for paleoenvironment and seasonality in the archaeological record. However, organic sources of δ¹⁸O and δD in mineralized tissue have remained largely unexplored. Here we measure the oxygen (δ¹⁸O) and hydrogen (δD) composition of dentin collagen sequentially sampled from the lower cheek teeth of four modern ovicaprids from the Baga Gazar'in Chuluu (BGC) region of the Gobi Desert of Mongolia. A significant correlation between trends in hydrogen and oxygen isotope values within individual teeth was identified. The amplitude of isotopic variation observed in sampled tooth dentin is similar to the yearly range of hydrogen and oxygen isotopic variation observed in meteoric precipitation for the region. These data indicate that dentin collagen δ¹⁸O and δD isotopic values reflect seasonal variation in the organic oxygen and hydrogen isotopic composition of diet and ingested water. We argue that paired measurements of dentin collagen δ¹⁸O and δD appear to be reliable seasonal climatic indicators.     

Impure and Worldly Geography:1 The Africanist Discourse of the Royal Geographical Society, 1831–73

The written networks through which knowledge is produced and circulated offer a focus for a theoretically informed critique of the formation of modern geographical knowledge. Drawing on deconstruction and colonial discourse theory, this paper presents a reading of the Royal Geographical Society's (RGS) published record of nineteenth-century African exploration. This discourse posits a racially unmarked subject-position as the condition of scientific discussion. The Society's geographical knowledge is shown to have been formed through the effacement of alternative subject-positions and the appropriation of other ways of knowing. It is suggested that closer attention to the discursive structures of written networks of knowledge might inform a more nuanced understanding of the reproduction of disciplined knowledge.