Clyde superficial deposits and bedrock models released to the ASK Network 2013 : a guide for users

This report draft provides an overview of the Clyde superficial deposits models to be released in 2013 and detail on the Central Glasgow Superficial Deposits Model currently released to the ASK network. The geological models are an interpretation of digital datasets held by the British Geological Survey. A summary of the construction and limitations of the models and a brief description of the modelled units is given. The report will be updated and revised as more models become available for release to the ASK network. More details on the models can be found in the previous reports Merritt et al. (2009), Monaghan (2012a) and Monaghan et al. (2012)

Postglacial evolution of bedrock rivers in post-orogenic terrains: the NW Scottish Highlands

Postglacial bedrock river erosion is likely to be a major control on the evolution of deglaciated landscapes. This study provides a quantitative assessment of bedrock channel change in a postglacial, post-orogenic terrain, encompassing the long-term evolution of bedrock channel distribution, geometry and the timing and rate of fluvial incision. In the NW Scottish Highlands, fluvial incision is focused on steep valley headwalls and at knickpoints formed at inherited glacial valley-floor steps (riegels). Holocene average incision rates of 0.4 – 1.3 m/kyr were measured using cosmogenic surface exposure dating (10-Be) at five strath terrace sites. Incision rates of 0.1 m/kyr were quantified from active channel beds and are lower than the Holocene average. This finding is consistent with a paraglacial decline in sediment supply being responsible for a reduction in fluvial incision in detachment-limited channels. Further support for a paraglacial sediment influence on bedrock channels is found in the long-term increase in the proportion of bedrock-exposure, reflecting a decrease in the critical slope threshold for the alluvial to bedrock channel transition. In reaches that have undergone a switch from alluvial to bedrock channel conditions, the onset of fluvial incision into bedrock was found to lag deglaciation by 2 – 4 kyr, suggesting that a substantial reduction in sediment availability occurred within several thousand years of ice retreat. Hydraulic conditions and substrate resistance are also major controls on the distribution and geometry of bedrock channels, and the rate of fluvial incision, in the NW Highlands. The geometry of both bedrock and alluvial channels was found to be strongly hydraulically scaled, with bedrock channels significantly narrower than coarse-grained alluvial channels. Lithology also governs the critical slope for alluvial to bedrock channel-transition; resistant metasedimentary bedrock produces relatively coarse-grained bed material with a high threshold for sediment entrainment, meaning that alluvial channels occur up to comparatively steep channel slopes. Lithological resistance also constrains the process and rate of fluvial incision. A new lithological resistance index, the ratio of joint spacing to intact rock strength, successfully discriminates between abrasion and plucking dominated channels and is non-linearly related to incision rate. The pulse of postglacial incision in bedrock channels has resulted in 2 – 8 m of entrenchment into valley floors since deglaciation. Bedrock channels narrow during entrenchment, achieving a consistent hydraulic geometry when entrenched to between 1 and 2 times the bankfull flow depth. Width adjustment occurs within 8 – 17 kyr of ice retreat, but adjustment of channel slope takes considerably longer and the long profiles of NW Highland rivers remain strongly glacially conditioned. Entrenchment disconnects channels from floodplains and may have contributed to the decline in paraglacial sediment flux, suggesting that fluvial incision may be a self-limiting process in post-orogenic postglacial terrains

Channel geometry data set for the northwest Scottish Highlands

This report provides the channel geometry data set to accompany the paper “Substrate, sediment and slope controls on bedrock channel geometry in postglacial streams” by Whitbread et al. (2015), published in the Journal Geophysical Research – Earth Surface (available from http://onlinelibrary.wiley.com/doi/10.1002/2014JF003295/full). The data set includes reach average channel geometry data (width and depth) for 139 reaches in the River Elchaig, River Canaird and River Carron (Dornoch Firth) in the northwest Scottish Highlands. The study reaches are classified according to the main substrate making up the banks and bed of the stream (Alluvial, Mixed bedrock – alluvial and Bedrock). Whitbread et al. (2015) use these data to assess differences in the downstream scaling of channel width and depth with catchment area (or discharge) for reaches developed in different substrates, and analyse the roles of slope and sediment in constraining channel geometry

The geomorphic impact of road construction : a case study of the A9 in Scotland

This study is a preliminary assessment of the geomorphic impacts of road construction based on two test areas located along the A9 in Scotland; a southern section 30 km in length just north of the city of Perth, and a northern section12.5 km in length just south of the city of Inverness. Estimates of the depths of cuttings and embankments formed during road construction have been made through comparison of ground levels recorded in pre-construction borehole logs along the road route with digital elevation models representing the modern ground surface. This study trials two methods of assessing surface change and the volume of material excavated or deposited along the road route. Firstly a direct comparison of borehole ground levels with the modern ground surface is used. The second method involves reconstruction of the pre-road ground surface through re-interpolation of the digital elevation models which are then validated by comparison with the actual pre-road ground level recorded in the boreholes. Volumes of material excavated and deposited are then derived by comparison of the re-interpolated digital elevation model with original (the modern ground surface). Both analysis methods indicate that there has been a net loss of material in the study areas, that equates to an average surface lowering along the road route of 2 to 2.5 m in the northern area, and 0.4 – 0.7 m in the southern area. Comparison of average rates of ‘erosion’ resulting from road construction with natural river erosion rates indicates that erosion associated with road construction occurs at rates that are 2 – 3 orders of magnitude faster than even the most rapid erosion recorded in natural streams worldwide, and 3 – 4 orders of magnitude faster than previously measured river erosion rates in Scotland. Only rare catastrophic flood events are capable of excavating gorges at rates equivalent to the rate of cutting excavation during road construction. The surface lowering and net material transfer associated with road construction is likely to strongly affect local geomorphic systems, with knock-on effects for hydrological and ecological systems in the vicinity of roads. As there are nearly 250 thousand miles of road within the UK, road construction is likely to have significant impacts on geomorphic and environmental systems at national scales

Assessment of on-farm, market and wild food diversity in three agro-ecological zones of Western Kenya

Poster presented at Tropentag 2014. International Conference on Research on Food Security, Natural Resource Management and Rural Development. "Bridging the Gap between Increasing Knowledge and Decreasing Resources" Prague (Czech Republic) Sep 17-19 2014

A study of aspects of synchronisation and communication in certain parallel computer architectures

This paper examines methods for synchronisation and communication between tasks in highly parallel arrays of processors. The development of various methods is researched and simulation techniques are applied to specific structures, to examine their effectiveness. Two approaches to simulation are presented, in the first case a discrete event simulator is applied to task synchronisation implemented with semaphores in a close coupled environment. Secondly the concurrent programming language Occam is used to simulate a systolic configuration of processors. In this case the design is verified, through actual system construction. Conclusions are drawn regarding the design disciplines and structure imposed by the use of these simulation techniques. A close relationship is found between the behaviour of a simulation written in Occam and the same structure constructed from multiple processors. Further research is suggested into the subject of dataflow processors, to find suitable means for simulating such systems, prior to implementation. A type of test vehicle is proposed that would operate a dataflow processor under the control of the development system

Looking like gold: Chlorite and talc transformation in the golden slip ware production (Swat valley, North-Western Pakistan)

The archaeometric study of the “golden slip” ware (second century BCE—fourth century CE) at the site of Barikot (Swat, north-western Pakistan) aimed to define its manufacturing technology and provenance of the raw materials used. For this reason, a multianalytical approach consisting of the microscopic, microstructural and mineralogical analysis of both the golden slip and the ceramic paste was adopted. The slip was found to be composed by platy minerals, microchemically identified as talc and chlorite; their intimate association indicated clearly that they derived from a chlorite-talc schist. This rock is geologically available near the site in the “green stones” lenses within the Mingora ophiolites outcropping in the Swat valley. Due to the use of this stone also for the production of stone tools, it cannot be excluded that the chlorite-talc schist used for the golden slip can be derived from manufacturing residues of the Gandharan sculptures. In order to constrain the firing production technology, laboratory replicas were produced using a locally collected clay and coating them with ground chlorite-talc schist. On the basis of the mineralogical association observed in both the slip and the ceramic paste and the thermodynamic stability of the pristine mineral phases, the golden slip pottery underwent firing under oxidising conditions in the temperature interval between 800°C and 850°C. The golden and shining looks of the slip were here interpreted as the result of the combined light reflectance of the platy structure of the talc-based coating and the uniform, bright red colour of the oxidized ceramic background

Devonian and Carboniferous stratigraphical correlation and interpretation in the Orcadian area, Central North Sea, Quadrants 7 - 22

This report details the stratigraphy and palaeogeography of Devonian and Carboniferous rocks of the northern sector of the UK Central North Sea (the ‘Orcadian Area’) for the 21CXRM Palaeozoic project. The work integrates the lithostratigraphic framework for the Middle Devonian to Late Carboniferous succession in the region of the Mid North Sea High developed in the first phase of the 21CXRM Palaeozoic project (Kearsey et al., 2015), with the Early Devonian to Early Carboniferous succession present in the north Central North Sea. This report describes the stratigraphical correlation of Devonian and Carboniferous strata of the Orcadian Basin and the northern extension of the Forth Approaches into the Witch Ground Graben (Quadrants 7 – 22). A lithostratigraphic framework for the region is presented, building on the work of Cameron (1993) and Marshall and Hewett (2003). For the Devonian strata, the lithostratigraphic framework developed by Marshall and Hewett (2003) is followed. Their study presented a substantial revision of the previous Devonian stratigraphy for the region, particularly related to (1) reassessment of the Devonian - Permian contact and (2) the identification of the Eday Group offshore in the Inner Moray Firth Basin. In this study, onshore outcrops, well data and seismic interpretation (cf. Arsenikos et al., 2016) verify the key elements of the framework of Marshall and Hewett (2003). In addition, well interpretations further define the extent of the stratigraphical units and form the basis of potential source and reservoir horizon palaeogeographic reconstructions for four time intervals within the Devonian succession. For example, the potential source rock of the Orcadia Formation has been interpreted to the north of the Halibut Horst and into the East Orkney Basin, significantly increasing the extent of this unit outside the Inner Moray Firth. A revised lithostratigraphic framework for the Carboniferous strata of Quadrants 14, 15, 20 and 21 is presented. This framework links the Carboniferous succession of the Orcadian Area with equivalent age strata in areas on and surrounding the Mid North Sea High (Kearsey et al., 2015). Well and seismic interpretations have been integrated to better define the extent of Carboniferous units. Regional facies variations for key time intervals in the Early Carboniferous are presented which highlight relationships between the Carboniferous basins of the Witch Ground Graben and Forth Approaches, and those of the Mid North Sea High and adjacent regions to the south. For example, fluvial channel systems have been interpreted within late Visean age coal-bearing, fluvial and lacustrine deposits of the Firth Coal Formation, that are potential feeder systems for Yoredale Formation fluvio-deltaic to marine deposits farther south. This report forms one of a series of outputs from the 21CXRM Palaeozoic project (Orcadian Area) and provides explanatory information for the associated digital datasets (spreadsheet). The Orcadian Area study follows previous work undertaken in the Mid North Sea High area of the Central North Sea (CNS area; Figure 1). Key elements of the regional petroleum geology of the Orcadian area are summarised in an accompanying synthesis report (Monaghan et al., 2016)

Landslide survey : High Lossit, near Machrihanish Bay, Mull of Kintyre

A walkover survey was carried out from the 20th to the 21st of February 2014 to inspect a landslide at High Lossit, Mull of Kintyre, Scotland [NR 62655, 19980]. The subsidence and ground deformation associated with the landslide affected an area of approximately 12 000 sq m of rough grazing land, bordering coastal cliffs, and causing minor damage to stone walls and fencing. The reported landslide occurred within the boundary of a larger, pre-existing landslide that probably occurred following deglaciation of the area during the Late Devensian. The original landslide had an estimated area of 40 000 sq m and likely occurred by rotational failure or sliding of deeply weathered basalt of the Clyde Plateau Volcanic Formation, forming a mass movement deposit comprising angular blocks of bedrock in a matrix of gravelly clay within an area bound by a 5 to 30 m high back-scarp. The recently reported landslide (with an area of approximately 12 000 sq m) is classified as a dominantly translational slide within the older landslide deposit, with rotation at the head of the landslide, developing into a translational slide in the main body and toe. The landslide is developed in a north to north-west facing slope, in gently north-east dipping basalt of the Clyde Plateau Volcanic Formation. The cause of the recent slope failure is likely due to a combination of driving forces including excessive water ingress after prolonged heavy rainfall, and existing slope instability due to the high slope angle and presence of large blocks of heavily weathered and altered basalt. The slope has a history of instability, reflected in the pre-existing scarp of the post-Late Devensian landslide and there is evidence for active soil movement prior to the recent slip recorded by offset of a stone wall at the foot of the recent slip. Large Post-Late Devensian landslips have been identified in numerous coastal locations around the Mull of Kintyre. The causes of these large landslips are poorly understood, but in the High Lossit area, intense weathering of basalts and local faulting in addition to over-steepening of the slope through glacial erosion may have been contributing factors to slope instability soon after deglaciation. Further assessment, including detailed geological mapping, would be required to properly understand the effect of the highly weathered and altered basalt on the ground stability and to develop the ground model. To assess for likelihood of future movement, a hydrogeological study of the site would also be required as the drainage of the affected field has been altered following the landslide