New research on the Holocene settlement and environment of the Chad Basin in Nigeria

Recent investigations of three archaeological sites in the Nigerian part of the Chad Basin during the Holocene reveal key stages in the cultural development and environmental history of that region. At Dufuna, a dugout boat was dated to around 6000 BC, making it the oldest known boat in Africa and one of the oldest in the world. Boats may thus have contributed to the mobility of the population of the southern edge of the Sahara 8000 years ago and, thereby, to the cultural homogeneity of this period. The pottery site at Konduga is around a thousand years younger than Dufuna but still belongs to the time of Mega-Chad. The site is on the Bama Ridge, an old shoreline. Its pottery, decorated in the Saharan tradition, belongs to the earliest ceramic phase of the West African Later Stone Age, long before the beginnings of food production. Although this site was probably settled by pioneers advancing into a largely flooded landscape along the slightly raised shoreline, the human occupation of the area previously covered by Mega-Chad began along a broad front around 2000 BC. Archaeological and palaeoecological finds from two settlement mounds at Gajiganna are described as case studies for this phase, which predates the well-known site of Daima.

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Résumé Les résultats présentés proviennent de recherches récentes sur trois sites archéologiques, dont chacun représente un épisode clé du développement culturel et de l'histoire environnementale du Bassin nigérian du Tchad au cours de l'Holocène. A Dufuna, la découverte d'une pirogue monoxyle, datée d'environ 6000 ans BC, constitue le témoignage le plus ancien d'une embarcation en Afrique et l'un des plus ancien dans le monde. Ce moyen de transport indique la mobilité des populations de la marge sud du Sahara à l'Holocène inférieur et moyen; ce qui a dû contribuer à l'homogénéité culturelle de cette période. Le site à poterie de Konduga est le plus jeune d'un millénaire que Dufuna, mais appartient à l'époque du Méga-Tchad. Le site est installé sur une ancienne ligne de rivage, la Bama Ridge. Sa poterie, décorée selon la tradition saharienne, appartient à la plus ancienne phase à céramique du Later Stone Age ouest-africain, bien avant le début d'une production alimentaire. Vu que ce site ne devait étre occupé que par des pionniers aventurés dans un paysage largement amphibie à la faveur d'un mince cordon émergé, la colonisation de l'espace antérieurement couvert par le Méga-Tchad, débute le long d'un large front vers 2000 ans BC.Les trouvailles archéologiques et paléoécologiques de deux tertres anthropiques à Gajiganna sont décrites commes études de cas illustrant cette phase, qui précède celle du célèbre site de Daima.

     

Stretching the Limits: Environmental Compensation, Habitat Creation and Sustainable Development

The rationales for ecological and landscape engineering are becoming absorbed within economistic interpretations of sustainable development grounded in maintaining 'environmental capital'. These interpretations incorporate the possibility of compensating for the adverse impacts of development with environmental benefits of equivalent worth, thus maintaining the 'stock'. Habitat creation is an important form of this 'environmental compensation'. This paper explores the conflicts surrounding environmental compensation as sustainable development is translated into policy and practice in the British planning system. The extent to which environment damage can be meaningfully compensated raises difficult questions of environmental values and technical expertise. Analysis at two levels – national planning policy and the negotiation of compensatory habitat creation for a specific development scheme – indicates that the pursuit of environmental compensation through present planning processes can serve to accommodate development interests. Furthermore, claims about the manageability of environmental impacts help legitimize particular patterns of economic growth.     

Time, Space, and Image Making: Rock Art from the Dhar Tichitt (Mauritania)

Prehistoric images are particularly versatile and difficult to grasp. In a few cases of historical continuity, local cultural glosses provide researchers with a rich corpus of data and help in the interpretation of the imagery. Such approaches contribute to the interpretation of the material in a frozen time perspective. Their impact on the development of archaeological methodologies enabling researchers to deal with strictly prehistoric image making traditions without any known descendant communities remains to be felt. This paper is an attempt to develop a subtle and robust archaeological methodology for the study of prehistoric images. The suggested approaches are replicable, and conclusions are falsifiable.Les images préhistoriques sont particulièrement versatiles, et leur sens difficile à cerner en raison de leur polysémie. Dans une poignée de cas, là ou il y a continuité historique, les chercheurs ont reussi à constituer une riche documentation sur les pratiques culturelles liées à l'utilisation des images. Ils/elles parviennent ainsi à des niveaux d'interpretation très detaillée, dans une conception paradoxalement réifiée des sociétés en question, conservant des pratiques culturelles inchangées pendant des millénaires. L'impact de telles approches sur l'élaboration de bonnes méthodes archéologique est négligeable. Dans la plupart des cas, les images et les vestiges matériels sont le uniques témoins des sociétés préhistoriques étudiées. Cet article s'efforce de developper des méthodes, à la fois subtiles et robustes, permettant une analyse systématique des images préhistoriques. Les méthodes proposées sont réplicables, et les conclusions refutables.     

Changes in the Physico-Chemical and Microbial Nature of Wetlands from the Leaching of Chromated Copper Arsenate (CCA)-Treated Wood

Abstract

Microbial activities are responsible for reducing the harmful effects of pollutants in different burial environments. Within wetlands in particular, microorganisms play an important role in the transformation of heavy metals and metalloids via direct or indirect oxidation/reduction. In turn, these microbial transformations can lead to the detoxification of pollutant elements such as copper, chromium and arsenic that comprise CCA-treated wood.

CCA was the most commonly used wood preservative in the UK (up until its partial ban in 2004). CCA prolongs the service life of wood by making it resistant to microbiological attack. As such, it has been regularly used in the construction of platforms and boardwalks in wetlands. However, recent concerns over the impact of the chemical constituents of this treatment on both the environment and human health have prompted the introduction of legislation in order to ensure that this type of treated wood is disposed of in accordance with the relevant health and safety guidelines.

In light of this information, it is important to assess changes in the physico-chemical and microbial nature of wetlands associated with the leaching of CCA from wooden structures. The results will not only provide a greater scope for understanding the implications associated with the in situ preservation of the archaeological resource contained within these environments, but also highlight the potential ramifications for wetland ecosystem dynamics.     

Overpressure and petroleum generation and accumulation in the Dongying Depression of the Bohaiwan Basin, China

The occurrence of abnormally high formation pressures in the Dongying Depression of the Bohaiwan Basin, a prolific oil‐producing province in China, is controlled by rapid sedimentation and the distribution of centres of active petroleum generation. Abnormally high pressures, demonstrated by drill stem test (DST) and well log data, occur in the third and fourth members (Es3 and Es4) of the Eocene Shahejie Formation. Pressure gradients in these members commonly fall in the range 0.012–0.016 MPa m^?1, although gradients as high as 0.018 MPa m^?1 have been encountered. The zone of strongest overpressuring coincides with the areas in the central basin where the principal lacustrine source rocks, which comprise types I and II kerogen and have a high organic carbon content (>2%, ranging to 7.3%), are actively generating petroleum at the present day. The magnitude of overpressuring is related not only to the burial depth of the source rocks, but to the types of kerogen they contain. In the central basin, the pressure gradient within submember Es32, which contains predominantly type II kerogen, falls in the range 0.013–0.014 MPa m^?1. Larger gradients of 0.014–0.016 MPa m^?1 occur in submember Es33 and member Es4, which contain mixed type I and II kerogen. Numerical modelling indicates that, although overpressures are influenced by hydrocarbon generation, the primary control on overpressure in the basin comes from the effects of sediment compaction disequilibrium. A large number of oil pools have been discovered in the domes and faulted anticlines of the normally pressured strata overlying the overpressured sediments; the results of this study suggest that isolated sandstone reservoirs within the overpressured zone itself offer significant hydrocarbon potential.     

Hydrothermal fluid flow models of stratiform ore genesis in the McArthur Basin, Northern Territory, Australia

This paper explores the role of basin‐scale fluid migration in stratiform Pb–Zn ore formation in the southern McArthur Basin, Australia. Mathematical models are presented for coupled brine migration and heat transport in the basin. The models account for: (i) topographically driven flow (forced convection) during periods when parts of the McArthur Basin were subaerial and elevated above the central Batten Fault Zone; (ii) density‐driven flow (free convection) during periods when the basin was mostly submarine; and (iii) transient flows associated with fault rupture during periods of transpression. These hydrologic models help to compare and contrast a variety of hypotheses concerning deep fluid migration and the origin of base metal ores in the McArthur Basin. The numerical results exhibit a strong structural control on fluid flow caused by the north‐trending fault systems that characterize the Batten Fault Zone. As a result, fluids descend to depths of a few kilometers along the western side, migrate laterally to the east through the clastic and volcanic aquifers of the upper Tawallah and lowest McArthur Groups, and then ascend along the eastern side of the fault zone. This recharge–discharge pattern dominates all of the hydrogeologic models. The basin‐wide flow pattern suggests that Na–Ca–Cl brines acquired base metals in the deepest levels of the basin stratigraphy as the fluids migrated eastwards through the aquifer system. Upward flow was relatively rapid along the Emu Fault Zone, so much so that fluid temperatures likely approached 130°C in the muddy sediments near the sea floor due to upward flow and venting at the HYC (‘Here’s Your Chance'). Transient pulses of flow characterized periods of transpressional stress and subsequent faulting may have punctuated the basin history. Large‐scale free convection, however, characterized notably long periods of diagenesis and ore mineralization during the Proterozoic in the McArthur Basin.     

The origin of deep subsurface microbial communities in the Witwatersrand Basin, South Africa as deduced from apatite fission track analyses

The first fission track analyses of detrital apatite grains from the subsurface of the Kaapvaal Craton were utilized to delineate the thermal history for the northern margin of the Witwatersrand Basin, South Africa, where evidence for subsurface thermophilic and hyperthermophilic microorganisms have been discovered. Fission track apatite ages for core samples ranged from 21 to 422 Ma. The trend of decreasing age with increasing depth parallels a trend previously reported for fission track data from surface samples collected from the higher altitude centre and lower altitude margins of the Kaapvaal Craton, South Africa. These new fission track ages are older than the surface samples of equivalent elevation, indicating that the uplift history and/or the geothermal gradient of the centre of the Kaapvaal Craton is distinct from that of its margins. Modelling of one sample collected from a depth of 3.7 km records cooling from 120°C at 75 Ma at a rate of approximately 1.4°C m.y.^?1 and reaching present day temperatures at 30 Ma. This modelling result when compared to other apatite fission track dates indicate that this cooling trend followed a 90‐Ma thermotectonic event. The fission track data also indicate that heated fluid migration, which is observed today in this region of the Witwatersrand Basin, was also active in the past in order to explain the greater palaeogeothermal gradient (18 versus 8°C km^?1). The fission track results suggest that at approximately 70 Ma only hyperthermophilic microorganisms could have existed at palaeodepths >3.2 km depth in the Witwatersrand Basin, and that the current meso/thermophilic microbial communities living at or beneath the present depth of 1.7 km in the Witwatersrand Basin must have migrated to their current location since 70 Ma. Any hyperthermophilic microorganisms found at the present depths 1.2–3.7 km could be descendents of subsurface hyperthermophiles that colonized the crust since the early Mesozoic to Palaeozoic eras.     

Analysis of the role of fluids in causing fractures in the Spraberry Trend,Midland Basin

The Spraberry Formation in west‐central Texas is a highly fractured formation with both extension and shear fractures. At least two sets of natural fractures exist in two reservoir intervals. We have considered two possible origins for the fracturing: (i) high fluid pressure plus tectonic stress and (ii) tectonic stress at near‐hydrostatic fluid pressure. Reconstruction of geologic, thermal and hydrodynamic histories suggests that high fluid pressures probably did not occur during the basin’s history. To explore the second hypothesis, we developed and applied a calibrated, discrete‐element model of Spraberry strata to investigate whether weak Laramide compressional forces could cause fractures in the absence of high fluid pressures. Simulation results suggest that a mild compressional episode of geologically short duration may indeed have induced conjugate shear fractures.     

Approaches to Prehistoric Diet Breadth, Demography, and Prey Ranking Systems in Time and Space

Zooarchaeological data on small game use hold much potential for identifying and dating Paleolithic demographic pulses in time and space, such as those associated with modern human origins and the evolution of food-producing economies. Although small animals were important to human diets throughout the Middle, Upper, and Epi-Paleolithic periods in the Mediterranean Basin, the types of small prey emphasized by foragers shifted dramatically over the last 200,000 years. Slow-growing, slow-moving tortoises, and marine mollusks dominate the Middle Paleolithic record of small game exploitation. Later, agile, fast-maturing animals became increasingly important in human diets, first birds in the early Upper Paleolithic, and soon thereafter hares and rabbits. While the findings of this study are consistent with the main premise of Flannery's Broad Spectrum Revolution (BSR) hypothesis (Flannery, K. V. (1969). In Ucko, P. J., and Dimbleby, G. W. (eds.), The Domestication and Exploitation of Plants and Animals, Aldine Publishing Company, Chicago, pp. 73–100), it is now clear that human diet breadth began to expand much earlier than the Pleistocene/Holocene transition. Ranking small prey in terms of work of capture (in the absence of special harvesting tools) proves far more effective in this investigation of human diet breadth than taxonomy-based diversity analyses published previously. Our analyses expose a major shift in human predator–prey dynamics involving small game animals by 50–40 KYA in the Mediterranean Basin, with earliest population growth pulses occurring in the Levant. In a separate application to the Natufian period (13–10 KYA), just prior to the rise of Neolithic societies in the Levant, great intensification is apparent from small game use. This effect is most pronounced at the onset of this short culture period, and is followed by an episode of local depopulation during the Younger Dryas, without further changes in the nature of Natufian hunting adaptations. An essential feature of the diachronic and synchronic approaches outlined here is controlling the potentially conflating effects of spatial (biogeographic) and temporal variation in the faunal data sets.     

Spatial-Temporal Evolution of the Distribution Pattern of Neolithic Sites in Han River Basin,China

ABSTRACT

This study analyzed the spatial and temporal distributions of 644 Neolithic sites in the Han River basin, China. The results showed that 31.06% of the Neolithic sites were distributed on low-altitude plains with an average altitude of 144.78 m; 22.98% were located on low platforms with an average altitude of 137.92 m, and 12.73% were distributed on low-altitude hills with an average altitude of 240.77 m. The aggregation fractal dimension (A), the proportion of pottery with carbon (PPMC) and the proportion of polished stone (PPST) were introduced to reveal the social development level. Meanwhile, the temperature anomalies (AT), total organic carbon content (TOC), total nitrogen content (TN), and carbon isotopic ratios (δ13C) were used to reveal the environmental context. Then, the correlation coefficients (hereafter, R) between different indicators were calculated. The result showed that a stable and suitable natural environment was a prerequisite for social development in the Neolithic Age. The persistent improvement in the ability of human beings to identify, manipulate and utilise nature was observed in the Neolithic Age in Han River basin, which marked the transformation of human society from hunting to farming and the start of human interactions with the natural world over time.     

Movements in Time and Space: Using Multiple Methods in Research with Young People in Accra,Ghana

The contribution discusses methodological issues involved in researching youth in an African context. Based on the experiences gathered during field research in Ghana, it is argued that research with young people in Africa requires careful reflexive practice. The rationale behind, and experience of, methods such as group discussions, oral life stories, lifelines, written diaries, photo-diaries and participant observation is critically discussed. It is argued that by combining these methods it is possible to capture the diversity and complexity of youth experiences in the present as well as longitudinal processes of transition. Moreover, combining different methods provides young people with the space and time they require to communicate the complexities of their lives.     

Imperial Expansion, Ethnic Change, and Ceramic Traditions in The Southern Chad Basin: A Terminal Nineteenth-Century Pottery Assemblage from Dikwa, Borno State, Nigeria

In the course of an archaeological project in the southern Chad Basin of Nigeria, excavations were conducted at several deeply stratified mound sites that date from the Late Neolithic to the Late Iron Age. As a way to complement the ceramic sequence obtained so far and to link it with today's pottery tradition, a small excavation was conducted at a site that dates to the turn of the nineteenth to the twentieth century A.D. A pottery assemblage was discovered that shows obvious links to today's tradition but notable breaks with those of the nineteenth century and earlier. This break in decoration style and technique is interpreted as an archaeologically visible expression of changing ethnic identity. This ethnic change and the associated spread of the ceramic tradition can be linked with the expansion of the sphere of power of the Kanem-Borno Empire into the area south of Lake Chad after the sixteenth century A.D.     

Origin of palaeo‐waters in the Ordovician carbonates in Tahe oilfield,Tarim Basin: constraints from fluid inclusions and Sr,C and O isotopes

Petrographic features, isotopes, and trace elements were determined, and fluid inclusions were analyzed on fracture‐filling, karst‐filling and interparticle calcite cement from the Ordovician carbonates in Tahe oilfield, Tarim basin, NW China. The aim was to assess the origin and evolution of palaeo‐waters in the carbonates. The initial water was seawater diluted by meteoric water, as indicated by bright cathodoluminescence (CL) in low‐temperature calcite. The palaeoseawater was further buried to temperatures from 57 to 110°C, nonluminescent calcite precipitated during the Silurian to middle Devonian. Infiltration of meteoric water of late Devonian age into the carbonate rocks was recorded in the first generation of fracture‐ and karst‐filling dull red CL calcite with temperatures from <50°C to 83°C, low salinities (<9.0 wt%), high Mn contents and high ⁸⁶Sr/⁸⁷Sr ratios from 0.7090 to 0.7099. During the early Permian, ⁸⁷Sr‐rich hydrothermal water may have entered the carbonate rocks, from which precipitated a second generation of fracture‐filling and interparticle calcite and barite cements with salinities greater than 22.4 wt%, and temperatures from 120°C to 180°C. The hydrothermal water may have collected isotopically light CO₂ (possibly of TSR‐origin) during upward migration, resulting in hydrothermal calcite and the present‐day oilfield water having δ¹³C values from ?4.3 to ?13.8‰ and showing negative relationships of ⁸⁷Sr/⁸⁶Sr ratios to δ¹³C and δ¹⁸O values. However, higher temperatures (up to 187°C) and much lower salinities (down to 0.5 wt%) measured from some karst‐filling, giant, nonluminescent calcite crystals may suggest that hydrothermal water was deeply recycled, reduced (Fe‐bearing) meteoric water heated in deeper strata, or water generated from TSR during hydrothermal water activity. Mixing of hydrothermal and local basinal water (or diagenetically altered connate water) with meteoric waters of late Permian age and/or later may have resulted in large variations in salinity of the present oilfield waters with the lowest salinity formation waters in the palaeohighs.     

Downward hydrocarbon migration predicted from numerical modeling of fluid overpressure in the Paleozoic Anticosti Basin,eastern Canada

The Anticosti Basin is a large Paleozoic basin in eastern Canada where potential source and reservoir rocks have been identified but no economic hydrocarbon reservoirs have been found. Potential source rocks of the Upper Ordovician Macasty Formation overlie carbonates of the Middle Ordovician Mingan Formation, which are underlain by dolostones of the Lower Ordovician Romaine Formation. These carbonates have been subjected to dissolution and dolomitization and are potential hydrocarbon reservoirs. Numerical simulations of fluid‐overpressure development related to sediment compaction and hydrocarbon generation were carried out to investigate whether hydrocarbons generated in the Macasty Formation could migrate downward into the underlying Mingan and Romaine formations. The modeling results indicate that, in the central part of the basin, maximum fluid overpressures developed above the Macasty Formation due to rapid sedimentation. This overpressured core dissipated gradually with time, but the overpressure pattern (i.e. maximum overpressure above source rock) was maintained during the generation of oil and gas. The downward impelling force associated with fluid‐overpressure gradients in the central part of the basin was stronger than the buoyancy force for oil, whereas the buoyancy force for gas and for oil generated in the later stage of the basin is stronger than the overpressure‐related force. Based on these results, it is proposed that oil generated from the Macasty Formation in the central part of the basin first moved downward into the Mingan and Romaine formations, and then migrated laterally up‐dip toward the basin margin, whereas gas throughout the basin and oil generated in the northern part of the basin generally moved upward. Consequently, gas reservoirs are predicted to occur in the upper part of the basin, whereas oil reservoirs are more likely to be found in the strata below the source rocks. Geofluids (2010) 10 , 334–350     

基于“十二五”规划视角的浦东新区旅游业发展研究——现状、问题及构想

“十二五”旅游业发展规划是将我国旅游业培育成国民经济战略性支柱产业与人民群众更加满意的现代服务业的关键性规划。本文基于“十二五”规划的视角,运用产业经济学理论,通过深入调查,对上海建设世界一流旅游目的地城市的重要区域——浦东新区的旅游业发展进行研究,其主要内容包括：（1）浦东新区旅游业发展的现状研究;（2）浦东新区旅游业发展评估及问题研究;（3）浦东新区旅游业“十二五”及至2020年的发展构想。本研究对其他类似区域制定旅游业发展的“十二五”规划具有一定的参考意义。     

Tourism and the management of cultural resources in the Pays Dogon,Mali

Abstract

The Pays Dogon, designated a joint Natural/Cultural World Heritage Site in 1989, is Mali's leading tourist attraction receiving 6,000 visitors per year with an annual growth of 10% which may increase when a new access road is constructed. Tourism is the major source of income for the Dogon who have lived in picturesque villages clinging to the sides of the 600m cliffs of the Bandiagara escarpment since the 15th century. The Dogon are best known to Europeans for their masked dances and powerful woodcarvings, much prized by collectors. Loss of cultural property by illicit trading combined with alteration of the traditional masked dances for visitor preference is contributing to cultural change within Dogon communities. The harmony and cohesion which enabled the Dogon to resist the colonial power is being threatened by a new set of historical constructs and priorities indicating that Dogon culture is more fragile when confronted with the 20th century.     

The Empire Meets the New Deal: Interwar Encounters in Conservation and Regional Planning

British imperial and American experiences in conservation and planning are providing fresh interdisciplinary challenges for university teaching and research. The Roosevelt administration's ‘New Deal’ included government‐sponsored interventions in soil erosion and water management and sophisticated regional development agendas. Reviewing samples of the latter areas of concern, this article explores the proposition that, although the British Empire was scarcely bereft of comparable interwar programmes and was becoming somewhat preoccupied with centrifugal tendencies, persistent porosity, exhausting struggles with postwar reconstruction, and comprehensive economic depression, New Deal evangelism was in fact variously anticipated, harnessed, challenged and ignored. A discussion of widely separated national and regional examples locates a layered interplay between uneven imperial and US pulsations, independent local manoeuvres, and critical inputs from key individual agents. The most important filters included the presence of comparatively robust bureaucratic infrastructures and the cultivation of international relationships by scientists and technologists. Encounters with convergent revisionism suggest cautionary leads for students, researchers and teachers alike. Reconstructions of selected contexts underline the presence of familiar posturing, opportunism, and astute patriotic deployment during the emergence of modern styles of globalization.     

Comments on Graf, Journal of Archaeological Science 36, 2009 “ “The Good, the Bad, and the Ugly”: evaluating the radiocarbon chronology of the middle and late Upper Paleolithic in the Enisei River valley, south-central Siberia”

Here I present a critical evaluation of the analysis conducted by Graf [Graf, K.E., 2009. “The Good, the Bad, and the Ugly”: Evaluating the radiocarbon chronology of the middle and late Upper Paleolithic in the Enisei River valley, south-central Siberia. Journal of Archaeological Science 36, 694–707] of the Paleolithic radiocarbon (¹⁴C) dataset for the Upper Paleolithic sites in the Yenisei River basin of Central Siberia. Graf applied a rating system to the corpus of existing ¹⁴C data for the region, and announced some new ¹⁴C dates. The results obtained, however, are highly biased due to several factors, including prejudice concerning the higher accuracy of the AMS technique in ¹⁴C dating and that ¹⁴C dates from the same cultural component should overlap with plus–minus two sigmas; ambiguities with the subdivision of the Lateglacial period; artificially high sample selection criteria; incomplete factual material; and unjustifiable and misleading statements on the ¹⁴C dating of fossil bones and the issue of Last Glacial Maximum human presence in Siberia. As a result, the conclusions made by Graf [Graf, K.E., 2009. “The Good, the Bad, and the Ugly”: Evaluating the radiocarbon chronology of the middle and late Upper Paleolithic in the Enisei River valley, south-central Siberia. Journal of Archaeological Science 36, 694–707] are unconvincing. New analysis is necessary in order to improve the quality of treatment of the original data for the Upper Paleolithic ¹⁴C chronology in the Yenisei River basin.