Statistics for Spatial Data.

Transactions of the Institute of British Geographers

Geological atlas of western and central Europe

Ecologists, biogeographers, and paleobotanists have long thought that climate and soils controlled the distribution of ecosystems, with the role of fire getting only limited appreciation. Here we review evidence from different disciplines demonstrating that wildfire appeared concomitant with the origin of terrestrial plants and played an important role throughout the history of life. The importance of fire has waxed and waned in association with changes in climate and paleoatmospheric conditions. Well before the emergence of humans on Earth, fire played a key role in the origins of plant adaptations as well as in the distribution of ecosystems. Humans initiated a new stage in ecosystem fire, using it to make the Earth more suited to their lifestyle. However, as human populations have expanded their use of fire, their actions have come to dominate some ecosystems and change natural processes in ways that threaten the sustainability of some landscapes.

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A burning story: The role of fire in the history of life

Recent developments in the direct-current geoelectrical imaging method

Application of Geophysical Techniques in Identifying Illegally Buried Toxic Waste

Eskers are useful for reconstructing meltwater drainage systems of glaciers and ice sheets. However, our process understanding of eskers suffers from a disconnect between sporadic detailed morpho-sedimentary investigations of abundant large-scale ancient esker systems, and a small number of modern analogues where esker formation has been observed. This paper presents the results of detailed field and high-resolution remote sensing studies into two esker systems that have recently emerged at Horbyebreen, Svalbard, and one at Breiðamerkurjokull, Iceland. Despite the different glaciological settings (polythermal valley glacier versus active temperate piedmont lobe), in all cases a distinctive planform morphology has developed, where ridges are orientated in two dominant directions corresponding to the direction of ice flow and the shape of the ice margin. These two orientations in combination form a cross-cutting and locally rectilinear pattern. One set of ridges at Horbyebreen is a hybrid of eskers and geometric ridges formed during a surge and/or jokulhlaup event. The other sets of ridges are eskers formed time-transgressively at a retreating ice margin. The similar morphology of esker complexes formed in different ways on both glacier forelands implies equifinality, meaning that care should be taken when interpreting Quaternary esker patterns. The eskers at Horbyebreen contain substantial ice cores with a high ice:sediment ratio, suggesting that they would be unlikely to survive after ice melt. The Breiðamerkurjokull eskers emerged from terrain characterised by buried ice which has melted out. Our observations lead us to conclude that eskers may reflect a wide range of processes at dynamic ice margins, including significant paraglacial adjustments. This work, as well as previous studies, confirm that constraints on esker morphology include: topographic setting (e.g. confined valley or broad plain); sediment and meltwater availability (including surges and jokulhlaups); position of formation (supraglacial, englacial or subglacial); and ice-marginal dynamics such as channel abandonment, the formation of outwash heads or the burial and/or exhumation of dead ice.

/pdf/equifinality-and-preservation-potential-of-complex-eskers-1127pmni54.pdf

Equifinality and preservation potential of complex eskers

Suspect burial excavation procedure: a cautionary tale

Soil carbon stores are a major component of the annual returns required by EU governments to the Intergovernmental Panel on Climate Change. Peat has a high proportion of soil carbon due to the relatively high carbon density of peat and organic-rich soils. For this reason it has become increasingly important to measure and model soil carbon stores and changes in peat stocks to facilitate the management of carbon changes over time. The approach investigated in this research evaluates the use of airborne geophysical (radiometric) data to estimate peat thickness using the attenuation of bedrock geology radioactivity by superficial peat cover. Remotely sensed radiometric data are validated with ground peat depth measurements combined with non-invasive geophysical surveys. Two field-based case studies exemplify and validate the results. Variography and kriging are used to predict peat thickness from point measurements of peat depth and airborne radiometric data and provide an estimate of uncertainty in the predictions. Cokriging, by assessing the degree of spatial correlation between recent remote sensed geophysical monitoring and previous peat depth models, is used to examine changes in peat stocks over time. The significance of the coregionalisation is that the spatial cross correlation between the remote and ground based data can be used to update the model of peat depth. The result is that by integrating remotely sensed data with ground geophysics, the need is reduced for extensive ground-based monitoring and invasive peat depth measurements. The overall goal is to provide robust estimates of peat thickness to improve estimates of carbon stocks. The implications from the research have a broader significance that promotes a reduction in the need for damaging onsite peat thickness measurement and an increase in the use of remote sensed data for carbon stock estimations.

Spatial statistics to estimate peat thickness using airborne radiometric data

In the exposed Upper Jurassic and Lower Cretaceous sediments along the northern margin of the Wessex Basin (Buckinghamshire to Wiltshire), structural and minor depositional basin orientations are often aligned NW to SE. Local depocentres in the late Jurassic and earliest Cretaceous rarely coincide with those of the mid-Cretaceous Lower Greensand. The “inversion” of these sub-basins is commonly across major NW-SE orientated faults; this change in the position of basins subsidiary to the Wessex Basin occurred in the time gap now represented by the base Lower Greensand unconformity (?Berriasian-mid-Aptian). It was during this time that subtle (or long term) shifts in basement structure became amplified. In this case sub-basin inversion is adequately explained by a long sedimentary hiatus rather than short lived active tectonism.

Alastair Ruffell

Papers

Application of Geophysical Techniques in Identifying Illegally Buried Toxic Waste

Equifinality and preservation potential of complex eskers

Suspect burial excavation procedure: a cautionary tale

Spatial statistics to estimate peat thickness using airborne radiometric data

Depositional trends in the Upper Jurassic-Lower Cretaceous of the northern margin of the Wessex Basin