Age and significance of the Quaternary cemented deposits of the Duje Valley (Picos de Europa,Northern Spain)

Cemented calcareous breccias appear in the Picos de Europa (Cantabrian Mountains, Spain) resting on glacially abraded surfaces and covered by moraines. U/Th dating of the calcite coating the clasts was successful in two samples, the oldest one indicating that the breccias accumulated during or prior to Marine Isotope Stage (MIS) 11, and the youngest indicating later cementation during MIS 8. The former introduces a limit for the age of the glaciation preceding the breccias, which cannot correspond to an event younger than MIS 12. This is the oldest absolute age so far obtained for intercalated glacial/interglacial deposits of the Iberian Peninsula.     

The Relationship of Place Re-Making and Watershed Group Participation in Appalachia

This article explores how participation in watershed groups creates a social space that mediates the relationship between biophysical places and place-protective action. We analyze qualitative data from a survey of more than 200 watershed group volunteers in the Appalachian region of the United States who were asked to describe experiences that encouraged or discouraged their participation. “Place” emerged as a key theme, with further delineations between made places (those highly affected by human activity, including coal extraction); natural places; and re-made places (those restored by the efforts of the watershed-group participants). Our findings suggest that the places themselves—and the natural, institutional, and social resources in these places—are more than a backdrop or setting for the volunteer activities; they also inspire, enhance, and are transformed by the act of volunteering.     

A Dasymetric Map of Maine Lobster Trap Distribution Using Local Knowledge

As coastlines face increased development pressure, it is important to have the best available spatial information on coastal activities, including commercial fishing. This article describes the creation of a fine-scale spatial representation of lobster fishing activity along the Maine coast of the United States using a combination of participatory geographic information systems (GIS) and dasymetric mapping methods. These methods are employed here to support data collection from a large number of active lobster harvesters while maintaining individual privacy. The resulting representation of the fishery is designed as a planning tool for identifying potential interactions between marine resources and human activities.     

Linking weathering and rock slope instability: non‐linear perspectives

Weathering is linked complexly to the erosion and evolution of rock slopes. Weathering influences both the strength of rock slopes and the stresses that act upon them. While weathering has often been portrayed in an over‐simplified way by those studying rock slope instability, in reality it consists of multiple processes, acting over different spatial and temporal scales, with many complex inter‐linkages. Through a demonstration of the sources of non‐linearities in rock slope weathering systems and their implications for rock slope instability, this paper proposes five key linkages worthy of further study. Copyright © 2012 John Wiley & Sons, Ltd.     

How effective are GIS in practice? A case study of British local government

Abstract

GIS have received increasing attention in recent years, particularly in local government. Despite the claims in the literature about the potential of the technology, to date there is still little information on the impact GIS applications are having on the organizations in which they are being implemented. With these considerations in mind this paper presents an evaluation of the findings of twelve case studies which were undertaken in a variety of British local government contexts during 1991 and 1992.

The evaluation of the findings of the case studies is divided into two parts. The first part indicates the limited impact GIS has had on the local authorities investigated even after at least two years experience. Given these findings the second part seeks to identify the issues which appear to be responsible for inhibiting the effective implementation of GIS in British local government. Overall it is suggested that some organizational cultures are inherently receptive and able to sustain the development of innovations such as GIS. However, whilst very few organizations are inherently innovative it was possible to identify four factors which appeared to enhance the chances of success. These are simple applications producing information which is fundamental to the work of potential users, user directed implementation involving the participation of all the stakeholders in the project, an awareness of the limitations of the organization with respect to the range of available resources, and a high degree of stability with respect to the general organizational environment, or alternatively an ability to cope with change. As a result the evaluation indicates that if GIS are to be effectively implemented much greater consideration must be given to the impact of organizational issues.     

The first climate refugees? Contesting global narratives of climate change in Tuvalu

Climate change effects such as sea-level rise are almost certain. What these outcomes mean for different populations, however, is far less certain. Climate change is both a narrative and material phenomenon. In so being, understanding climate change requires broad conceptualisations that incorporate multiple voices and recognise the agency of vulnerable populations. In climate change discourse, climate mobility is often characterised as the production of ‘refugees’, with a tendency to discount long histories of ordinary mobility among affected populations. The case of Tuvalu in the Pacific juxtaposes migration as everyday practice with climate refugee narratives. This climate-exposed population is being problematically positioned to speak for an entire planet under threat. Tuvaluans are being used as the immediate evidence of displacement that the climate change crisis narrative seems to require. Those identified as imminent climate refugees are being held up like ventriloquists to present a particular (western) ‘crisis of nature’. Yet Tuvaluan conceptions of climate challenges and mobility practices show that more inclusive sets of concepts and tools are needed to equitably and effectively approach and characterise population mobility.     

Coarse clast ridge sequences as suitable archives for past storm events? Case study on the Houtman Abrolhos,Western Australia

Prehistoric storm records are relatively scarce in most parts of the world. This article presents storm records derived from coral rubble‐based geological archives of the Houtman Abrolhos Archipelago located off the west coast of Australia, where the southernmost coral reefs of the Indian Ocean are found. Winter storm swell from the circum‐Antarctic ‘Brave Westerlies’, as well as tropical cyclone waves, have left numerous ridge systems on dozens of islands of the archipelago, all composed of coral rubble from adjacent reefs. At three islands, seven ridge systems were dated by three different methods: U‐series (68 dates), radiocarbon (64 dates), electron spin resonance (7 dates); 139 radiometric dates span the last 5500 years of the Holocene. In contrast to the geomorphological interpretation, the age sequences show ‘inversions’, hiatuses and different ages for the same ridge, all pointing to complicated ridge formation processes. Time gaps, some exceeding 1000 years, are interpreted as phases of erosion and not as phases without storm activity. Copyright © 2012 John Wiley & Sons, Ltd.     

A new approach to define surface/sub-surface transition in gravel beds

The vertical structure of river beds varies temporally and spatially in response to hydraulic regime, sediment mobility, grain size distribution and faunal interaction. Implicit are changes to the active layer depth and bed porosity, both critical in describing processes such as armour layer development, surface-subsurface exchange processes and siltation/ sealing. Whilst measurements of the bed surface are increasingly informed by quantitative and spatial measurement techniques (e.g., laser displacement scanning), material opacity has precluded the full 3D bed structure analysis required to accurately define the surface-subsurface transition. To overcome this problem, this paper provides magnetic resonance imaging (MRI) data of vertical bed porosity profiles. Uniform and bimodal (?? _g = 2.1) sand-gravel beds are considered following restructuring under sub-threshold flow durations of 60 and 960 minutes. MRI data are compared to traditional 2.5D laser displacement scans and six robust definitions of the surface-subsurface transition are provided; these form the focus of discussion.     

Patterns of Entrapped Air Dissolution in a Two‐Dimensional Pilot‐Scale Synthetic Aquifer

Past studies of entrapped air dissolution have focused on one‐dimensional laboratory columns. Here the multidimensional nature of entrapped air dissolution was investigated using an indoor tank (180 × 240 × 600 cm³) simulating an unconfined sand aquifer with horizontal flow. Time domain reflectometry (TDR) probes directly measured entrapped air contents, while dissolved gas conditions were monitored with total dissolved gas pressure (P_TDG) probes. Dissolution occurred as a diffuse wedge‐shaped front from the inlet downgradient, with preferential dissolution at depth. This pattern was mainly attributed to increased gas solubility, as shown by P_TDG measurements. However, compression of entrapped air at greater depths, captured by TDR and leading to lower quasi‐saturated hydraulic conductivities and thus greater velocities, also played a small role. Linear propagation of the dissolution front downgradient was observed at each depth, with both TDR and P_TDG, with increasing rates with depth (e.g, 4.1 to 5.7× slower at 15 cm vs. 165 cm depth). P_TDG values revealed equilibrium with the entrapped gas initially, being higher at greater depth and fluctuating with the barometric pressure, before declining concurrently with entrapped air contents to the lower P_TDG of the source water. The observed dissolution pattern has long‐term implications for a wide variety of groundwater management issues, from recharge to contaminant transport and remediation strategies, due to the persistence of entrapped air near the water table (potential timescale of years). This study also demonstrated the utility of P_TDG probes for simple in situ measurements to detect entrapped air and monitor its dissolution.     

Rock‐protecting seaweed? Experimental evidence of bioprotection in the intertidal zone

Biogeomorphological processes are an important component of dynamic intertidal systems. On rocky shores, the direct contribution of microorganisms, plants and animals to weathering and erosion is well known. There is also increasing evidence that organisms can alter rock breakdown indirectly, by moderating temperature and moisture regimes at the rock–air interface. These influences have been purported to represent mechanisms of bioprotection, by buffering microclimatic fluctuations associated with weathering processes such as wetting and drying and salt crystallization. However, virtually nothing has been done to test whether microclimatic buffering translates to differences in actual rock breakdown rates. Here we report a preliminary laboratory experiment to assess how an artificial canopy (chosen to represent seaweed) affects mechanical rock breakdown. Using a simplified and accelerated thermal regime based on field data from a rocky shore platform in southern England, UK, we find that breakdown (mineral debris release) of mudstone covered with a canopy is reduced by as much as 79% relative to bare rock after around 100 thermal cycles. Reduction in rock surface hardness (measured using an Equotip device) was also greater for bare rock (17%) compared to covered rock (10%) over this period. Measurements of salt crystal formation indicate that the mechanism driving these differences was a reduction in the frequency of crystallization events, via moisture retention and shading of the rock surface. Copyright © 2015 John Wiley & Sons, Ltd.