Hydrography and dynamics of the Ría de Ribadeo (NW Spain), a wave driven estuary

The Ría de Ribadeo, a small embayment in NW Spain, was observed for the first time using three months of ADCP (Acoustic Doppler Current Profiler) current meter records and three CTD (Conductivity Temperature Depth) surveys. A wave driven circulation pattern arises from the observations, instead of the shelf wind driven circulation of other Galician Rias. Based on ADCP records, a unidirectional flow in the horizontal velocity field coexists with the classic two-layer circulation (bidirectional flow). The proposed horizontal circulation pattern can then be explained as a wave driven inflow. This flow enters the ria through the west side, describes an anticlockwise gyre inside of it, and flows out through the east side. Numerical simulations run with the HAMSOM (Hamburg Shelf Ocean Model) agreed with observations, confirming the proposed pattern.     

Negotiating Expectations in the Field: Gatekeepers, Research Fatigue and Cultural Biases

This paper considers disjunctures between my expectations and experience of doing dissertation fieldwork, which I conducted in Benin between the autumns of 1997 and 1998. The research examined the nature of women's livelihood strategies and their associated outcomes in terms of material well‐being. I now believe that my feminist worldview, and my growing exhaustion as the project progressed, resulted in my minimising the importance of key aspects of fieldwork in an African context. Specifically, I downplayed the importance of negotiating with male “gatekeepers” in gaining access to the women with whom I wanted to work. While most of the time I was able to manage this well enough, one day, in particular, stands out as a time when I handled these negotiations very poorly. This paper compares the experiences of that day with another much more productive and fruitful one to examine how and why expectations and experience can diverge. A consideration of some of the issues that resulted in the “lost day” might prove instructive for other researchers.     

Mobilizing research on Africa's development corridors

Across Africa, development corridors – networks of roads, railways, pipelines and ports that facilitate the movement of commodities between landlocked production areas, processing zones and global markets – are being built at an unprecedented pace. In mainstream development discourse, these mega-infrastructure projects have been framed as an effective way of creating conditions that are attractive to investors while simultaneously driving inclusive economic growth and development. Yet, recent geographic research on new development corridors has revealed certain tensions and inconsistencies in this win–win narrative, drawing attention to cases where the spatial reorganization of land that has accompanied corridor development has introduced new patterns of spatial exclusion and immobility. This article shows how approaching the study of development corridors using the new mobility paradigm – paying attention to uneven and conflicting mobilities along new corridor routes – stands to generate important empirical and theoretical insights about peoples' lived experiences with corridors, as well as about the trajectories of power enacted through corridor development. Ultimately, it is argued that applying the new mobilities paradigm in future research on development corridors may help researchers to better understand emergent forms of spatial exclusion and immobility created by new corridors.     

Artisanal and small-scale mining (ASM) in sub-Saharan Africa: Re-conceptualizing formalization and ‘illegal’ activity

This article contributes to the debate on the formalization of artisanal and small-scale mining (ASM) – low-tech, labour-intensive mineral extraction and processing – in developing countries. A unique sector populated by an eclectic group of individuals, ASM has expanded rapidly in all corners of the world in recent years. Most of its activities, however, are informal, scattered across lands which are not officially titled. But growing recognition of the sector's economic importance, particularly in sub-Saharan Africa, has forced donors, and to some extent, policymakers, to ‘rethink’ development strategies for ASM. As part of broader moves to improve the regulation of, and occasionally intensify the delivery of assistance to, the sector, many are now searching frantically for fresh ideas on how to bring operations into the legal domain, where, it is believed, they can be regulated, monitored and supported more effectively. A challenging exercise, this entails first determining, with some degree of precision, why people choose to operate informally in this sector. Drawing on analysis from the literature and findings from research conducted in Ghana and Niger, it is argued that the legalist school (on informality) in part explains how governments across sub-Saharan Africa are ‘creating’ bureaucracies which are stifling the formalization of ASM activities in the region. A more nuanced development strategy grounded in local realities is needed if formalization is to have a transformative effect on the livelihoods of those engaged in ASM in the region and elsewhere in the developing world.     

Integrating Women and Environmental Issues into World Regional Geography

Abstract

Women throughout the world are demonstrating solidarity and activism on behalf of environmental issues. A World Regional Geography course is an appropriate setting for discussing some of the contributions women make to protect the environment. Using case studies that draw upon women's environmental activism in four world cultures, this article presents content information, instructional strategies and instructional resource lists. The four world cultures that provide the backdrop for this discussion are Anglo America, Russia and its neighbors, Sub-Saharan Africa and South Asia.     

The sedimentary signature of ice-contact sedimentation and deformation at macro- and micro-scale: A case study from NW Scotland

Studies on the genesis of subaerial debris flows and associated deposits are relatively rare in the literature, especially in an ice-marginal context of moraine formation. The present contribution reports results from both the macro- and micro-scales of a subaerial depositional setting in order to contribute to closing this gap. At the macroscale, alternating loose, stratified, clast- and matrix-supported diamicts and finely laminated sand units indicate deposition of debris flows and fluvial units in a subaerial, ice-marginal setting that were stacked up to form a terrestrial ice-contact fan. Macroscale and micromorphological analyses show that this fan displays evidence of a three-phased formation: (a) overriding and glaciotectonisation of pre-existing sediments followed by retreat and burial of this core by (b) ice-contact fan deposition dominated by water-rich fluvial deposition with relatively little debris flow activity and (c) a switch to a gravitational sedimentation style with dominantly debris flow deposition and fewer and thinner fluvial units. Thin sections of both the diamict and laminated sand units show evidence of deposition of a mud and fine sand-rich slurry being expelled from the tops of advancing mass flows. Water-rich fine-grained slurries appear to have been progressively overridden and deformed in response to ductile shear occurring at the base of individual flows. Liquefaction and remobilisation of sand within laminated deposits occurred during such basal shear events, resulting in the injection of liquefied sediments into variably deformed laminated sands and clays. Deformation is more likely to have taken place through internal movement of the sediment due to changing porewater conditions and loading upon emplacement. Our approach confirms previous results that highlight the possibilities of increasing the accuracy of sedimentological investigations through combined sedimentological analyses at varying scales.     

Early Permian to Middle Jurassic rifting and sedimentation in East Africa and Madagascar

Pre-drift sediments of Madagascar (Early Permian-Middle Jurassic) have been studied palynologically. These studies resulted in a more precise dating of individual stratigraphic units and the recognition of minor and major breaks in the succession. Palynostratigraphic and physical evidence of unconformities have been used to subdivide the pre-drift sediments into depositional cycles and to infer rifting events. A comparison with equivalent strata of Mozambique, Tanzania, Kenya, Ethiopia and Somalia shows a general correspondence and provides additional information for the construction of a generalized framework for the East African/Madagascan region which demonstrates the relationships between rifting and sedimentation and elucidates the prehistory of the break-up of Gondwana into a western and eastern fragment during the Middle Jurassic. The predrift succession of East Africa/Madagascar can be subdivided into two major sequences, a Karoo sequence (cycles 1–5, Asselian-early Smithian) and a transitional sequence (cycles 6–9, Ladinian-early Bajocian). The two sequences are separeted by a late Scythian to Anisian hiatus which indicates extensive uplift and erosion before a major rifting event initiated the resumption of sedimentation in the Ladinian. This Middle Triassic event marks the transition from the intracratonic rift stage to the pericratonic basin stage and correlates with a significant event in the Pangaean history, the transition from final coalescence to initial dispersal. The onset of the southward drift of Madagascar is believed to have occurred about 60 Ma later near the Aalenian-Bajocian boundary, contemporaneous with or immediately after the deposition of syntectonic sediments of cycle 9.     

Paleolimnological investigations of anthropogenic environmental change in Lake Tanganyika: II. Geochronologies and mass sedimentation rates based on <Superscript>14</Superscript>C and <Superscript>210</Superscript>Pb data

We established sediment geochronologies for cores from eight deltaic areas in Lake Tanganyika (the Lubulungu, Kabesi, Halembe, Malagarasi, Nyasanga/Kahama, Mwamgongo, Nyamusenyi, and Karonge/Kirasa River deltas), recording a range of watershed disturbance histories from the eastern margin of this African rift valley lake. Cores from currently disturbed sites on the central Tanzanian coast display remarkably uniform and low rates of sediment accumulation from the 18th century until the early 1960s, when a synchronous and dramatic rise in rates occurs. Through this same time interval sedimentation rates offshore from undisturbed Tanzanian watersheds either remain unchanged or decline. Further north, at disturbed sites along the northern Tanzania and Burundi coasts, the pattern of sedimentation rate increase is more complex. Although a mid-late 20th century increase is also evident in these sites, indications of earlier periods of increasing sediment erosion, dating from the mid-late 19th century, are also evident. Synchronous changes in sediment accumulation rates dating from the early 1960s may be the result of exceptionally wet years triggering an increase in the discharge of previously eroded and unconsolidated alluvium and stream/beach terrace deposits, previously accumulated in the deltas and stream valleys of impacted watersheds. Sedimentation rate impacts of deforestation on lake ecosystems are likely modulated by short-term climatic forcing events, which can impact the specific timing and location of sediment discharge to lakes.