The origin of overpressure in 'old' sedimentary basins: an example from the Cooper Basin, Australia

Overpressure in ‘old’ sedimentary basins that have not undergone rapid, recent sedimentation cannot be easily explained using traditional burial‐driven mechanisms. The last significant burial event in the Cooper Basin, Australia, was the Late Cretaceous deposition of the Winton Formation (98.5–90 Ma). Maximum temperature in the basin was attained during the Late Cretaceous, with cooling beginning prior to 75 Ma. Hence, overpressure related to rapid burial or palaeomaximum temperatures (e.g. hydrocarbon generation) must have developed prior to 75 Ma. Retaining overpressure for 75 Ma in ‘old’ basins such as the Cooper Basin requires extremely low seal permeabilities. An alternative explanation is that overpressure in the Cooper Basin has been generated because of an increase in mean stress associated with an increase in horizontal compressive stress since Late Cretaceous times. Structural observations and contemporary stress data indicate that there has been an increase in mean stress of approximately 50 MPa between Late Cretaceous times to that presently measured at 3780 m. The largest measured overpressure in the Cooper Basin is 14.5 MPa at 3780 m in the Kirby 1 well. Hence, disequilibrium compaction driven by increasing mean stress can explain the magnitude of the observed overpressure in the Cooper Basin. Increases in mean stress (tectonic loading) may be a feasible mechanism for overpressure generation in other ‘old’ basins that have undergone a recent increase in horizontal stress (e.g. Anadarko Basin).     

Genetic characterization of an archaeological sheep assemblage from South Africa’s Western Cape

The Neolithic Revolution, constituting a shift from food acquisition to food production, came to Africa as it did to most of the rest of the world: through processes of transmission rather than through de novo innovation. In contrast with other regions the pastoral management of cattle, sheep and goats was widespread in Africa thousands of years before settled agricultural communities or the use of domesticated plants were in evidence ( 46, 35 and 10). We report here the discovery of haplogroup B in the first genetic analysis of an African archaeological sheep assemblage.     

Maps and the settlement of southern Palestine, 1799–1948: an historical/GIS analysis

Historical maps of the Negev Desert which comprises half of the total land area of Palestine can be viewed from several intersecting perspectives relating to aspects such as their contribution to tracing patterns of settlement and agricultural history, imperialism and mapping, and legal geography of land ownership and indigenous people. Here we focus mainly on the first theme, incorporate new methods and demonstrate their application to studies in historical geography.     

The use of a high-resolution 3D Chirp sub-bottom profiler for the reconstruction of the shallow water archaeological site of the Grace Dieu (1439), River Hamble,UK

The remains of Henry V's flagship, the Grace Dieu, currently lie buried within the inter-tidal sediments of the River Hamble (S. England). Previous archaeological investigations have been hindered by difficult excavation conditions resulting in a poor understanding of the dimensions, shape and degradation state of the hull's deeper structure. This study therefore aimed to image, characterize and reconstruct the buried remains of this vessel using a high-resolution 3D acoustic sub-bottom Chirp system with RTK-GPS positioning capability. The accurate navigation and high-resolution data that were acquired enabled the construction of a full 3D image of the site that not only identified the remains of the wooden hull, but also features buried within it. In addition, the degradation state of these buried wooden remains were investigated by calculating reflection coefficients while a hypothetical larger reconstruction of the Grace Dieu's hull was achieved, through the use of the ShipShape ship design software package.     

Towards a political geography of hotels: Southern Rhodesia, 1958–1962

This article sets out the case for taking account of hotels in political geography. It argues that hotels, as key spaces of welcome, association, and entertainment between public and private, are important political sites. They provide space for the performance of political ideologies and identities, where political campaigns can be made visible, where political relations can be illuminated and translated for international audiences, and where the ‘little things’ (Thrift, 2000, Thrift, 2004) that construct political geographies can be examined. Drawing on theoretical discussions of hospitality, as well as work in political geography, it explores the politics of multi-racial hospitality in the hotels of Salisbury, Southern Rhodesia, between 1958 and 1962 in order to understand late colonial politics in Southern Africa. Considering three individual hotels, the paper elaborates their role as keys spaces in the landscape of exclusive ‘European’ sociability; as crucial sites in the enactment of and resistance to the colour bar; and as vantage points on Southern Rhodesian racial politics for international guests. The papers shows that far from being peripheral to the ‘real’ politics of diplomacy and government, hotels and the hospitable practises within them can be seen as crucial elements in the construction of local, national and international politics.     

Counselling Citizens and Producing Patronage: AIDS Treatment in South African and Ugandan Clinics

Global health interventions to provide antiretroviral (ARV) drug treatment for people living with HIV/AIDS in developing countries have linked global and local actors in unprecedented ways. These uneven relationships have been described as creating new forms of citizenship that challenge the liberal understanding of rights and responsibilities bestowed by the state. A comparative case study based on fieldwork from South Africa and Uganda suggests different theoretical understandings of the link between technologies of AIDS treatment and relationships of belonging. Yet, ethnographic data from local clinics in both countries point to similarities that exist across AIDS interventions, and to the importance of counsellors in negotiating the rules of ARVs. Neither patients living with HIV nor the local providers of their AIDS treatment are ‘bare life’ subjects to be acted upon by a global development intervention. As ARV technologies are increasingly prescribed in developing country clinics, diverse social relationships are taught and negotiated as part of the pedagogy of biopolitics. The following discussion demonstrates how local counsellors and clients negotiate the rules of AIDS treatment together for mutual benefit. The article concludes that AIDS treatment creates relationships of therapeutic citizenship and clientship in ways that constrain the possibilities of citizenship and development.     

Stability of phytoliths in the archaeological record: a dissolution study of modern and fossil phytoliths

Opaline phytoliths are important microfossils used in archaeological and ecological research. Relatively little is known about the stability of phytoliths after burial. Under alkaline pH conditions they can dissolve, and mechanical disturbances can cause a loss of their more delicate appendages. Here we present an experimental study of phytolith stability (combination of solubility and abrasion). Modern and fossil phytoliths were extracted from wheat using new methods to minimize dissolution, and by burning in an oven. These assemblages were placed in a solution buffered to pH 10 and maintained under constant temperature and shaking conditions. The silicon concentrations in the solution were monitored once a week for 5 weeks. The phytolith morphologies in each assemblage were determined at the outset of the experiment and after 5 weeks. The results show that there are differences in stability between various assemblages. Modern inflorescence wheat phytolith assemblages are more unstable than those from leaves/stems. Burnt assemblages are less stable than unburnt assemblages, and a fossil phytolith assemblage about 3000 years old is more stable than the modern wheat assemblages. The results also show that individual phytolith morphotypes have different stabilities, and as a result of dissolution and abrasion, some morphotypes may resemble others. This study further shows that archaeological and/or paleo-environmental interpretation of phytolith assemblages may change with the assemblage’s state of preservation.