Core sedimentology, stratigraphic architecture and 3D seismic geomorphology are integrated in order to: (a) demonstrate the criteria for recognition of coarse-grained subaqueous deltas in the stratigraphic record; (b) compare them with modern examples; (c) develop a new method to extract progradation rates from ancient shallow-marine clinoforms; and (d) refine the depositional model of the Upper Jurassic Sognefjord Formation, which forms the main reservoir in the super-giant Troll Field (Norwegian North Sea). The Sognefjord Formation is a 10-200 m thick clastic wedge, deposited in ca. 6 Myr, by a fully marine deltaic system that was sourced from the Norwegian mainland. A series of 10-60 m thick, westerly-dipping subaqueous clinoform sets are developed within this unit and can be mapped for several tens of kilometres along strike. Within each clinoform set, clinothems are formed by regressively stacked sandstone-rich bedsets, devoid of subaerial facies and separated by thin mudstone intervals. Near-horizontal trajectories are observed in each clinoform set, and the sets are stacked vertically. In the eastern half of the field, individual clinoforms are relatively gently dipping (1-6°) and bound thin (10-30 m) clinothems dominated by fine-grained, hummocky cross-stratified sandstones. Towards the west, clinoforms gradually become steeper (5-14°) and bound thicker (15-60 m) clinothems that comprise medium-grained sandstones in their upper parts. Topsets are usually well developed. Quantification of clinoform age and progradation rates is constrained by regionally correlatable bioevents, and relies on exponential age-depth interpolations. The facies break that mirrors the foreset-to-bottomset transition, which represents storm wave base, is subsequently dated, and progradation rates are measured along transects tied to well correlations and seismic interpretations. The results indicate falls in progradation rate (from 500 to 30 km/Myr) and net sediment flux (from 90 to 10 km2/Myr), and a simultaneous rise in vertical sedimentation rate (from 15 to 70 m/Myr) towards the basin; these variations are attributed to the progradation of the subaqueous delta into progressively deeper waters associated with along-shore currents that provide net sediment transport out of the study area, as well as sculpting the linear, elongated clinoforms. Coarse-grained subaqueous deltas provide a new interpretative template that may be applicable to other ancient clinoform-bearing shallow-marine sandstones with reservoir potential, whilst calculation of progradation rates provides a tool to improve reservoir characterisation and near-field exploration by enhancing prediction of reservoir distribution and character.

Combined seismic and well interpretation methods can be used to elucidate detail of the subsurface architecture of fluvial and fluvio-deltaic deposits. Observations made from wireline and core logs, including facies and analysing the relative proportions of architectural elements and facies associations indicative of depositional sub-environments, can be used to interpret patterns of cyclicity, changes in local accommodation conditions, and periods of increased seasonal, tidal and marine influence. Horizon slices, taken from 3D seismic volumes aid in the visualisation of laterally discontinuous, often thinly-bedded, fluvial deposits. Seismic facies, when combined with core and wireline log facies, can be interpreted as a series of ‘seismic elements’. The relative proportions of seismic elements mapped out on horizon slices allows the interpretation of depositional environments and accommodation setting; allowing the distinction between fluvial and deltaic settings. A number of data conditioning and seismic interpretation techniques can be used to enhance the visualisation of channelized and non-channelized fluvio-deltaic deposits in the subsurface. Frequency decomposition (and the making of colour-blended volumes) allows the visualisation of the detail of channel belt deposits such as channel belt migration and lateral accretion deposits. Allogenic processes, particularly base-level (buttress) rise and fall have been shown to exert a control on the overall stacking pattern of the studied fluvio-deltaic deposits, whereas autogenic processes are interpreted as the major control on the local arrangement and architecture of channel belt and overbank deposits. The first study in this thesis uses the Upper Permian Rangal Coal Measures, a large-scale fluvial system, which accumulated in a foreland basin setting in the Bowen Basin, Queensland, Australia. The study investigates the architecture and connectivity of splay and distributary channels. The second study uses the Late Triassic Mungaroo Formation, a Mississippi-scale fluvio-deltaic system with a fluvially-dominated, tidally-influenced delta, which accumulated in the Northern Carnarvon Basin, Northwest Shelf, Australia. The study investigates different seismic interpretation techniques and investigates the relative control on fluvio-deltaic deposition of allogenic and autogenic processes.

Radioactive caesium (137Cs) and strontium (90Sr) are two of the most important contaminant radionuclides present in many terrestrial environments, as a result of accidental and approved releases from anthropogenic nuclear activity. This thesis investigates the sorption of Cs and Sr onto the surfaces of common terrestrial minerals and a mixed phase sediment. The key findings of the work were with regard to the effect of solution pH and ionic strength on changing the mechanism of Cs and Sr interaction with reactive mineral surfaces. Caesium was found to sorb to multiple sorption sites within the mixed phase sediment. The first of these was a Cs selective site at the edge of the illite interlayer, known as the frayed edge site. It was determined from electron microscopy and x-ray absorption spectroscopy that Cs was selectively incorporated and retained in the interlayer structure in inner-sphere complexes. Cs was also found to sorb to two other main sorption sites in competition with other cations. Therefore the concentrations of Cs sorbing to the mineral surfaces were greatly reduced in low pH or high ionic strength conditions. Solution pH and ionic strength also played a major role in Sr sorption. At intermediate pH Sr sorbed to the surface of illite, chlorite and goethite in outer-sphere complexes. Therefore the presence of competing ions in solution significantly reduced total Sr sorption. However, at very high pH, Sr was specifically adsorbed into inner-sphere surface complexes. This allowed significant concentrations of Sr to sorb to the mineral surface even in high ionic strength solutions. The findings of this thesis mark a significant advance in understanding the fundamental processes governing the behaviour of 137Cs and 90Sr in the environment. Particularly it shows the importance of groundwater chemistry in governing sorption behaviour.

The Bowland and Lancaster Fells Basins of north-west England contain a Pendleian El, sequence up to 650m thick, most of which is coarse clastic material. Each of the major stratigraphic units in this sequence, namely the Pendle and Grassington Grit Groups, represents a phase of clastic input to the basins. Initially, the basins were deep marine troughs with water depths of several hundreds of metres. Their northern margins were steep submarine slopes or relict fault scarps rising up onto the partially emergent Askrigg and Lake District Blocks. Within the basins there was significant topographic relief caused by differential compaction over buried Dinantian fault blocks. The Pendle Grit Group, comprising the Pendle Grit and Pendle Shale Formations, represents the development of a sand-rich submarine fan/slope system in these confined basins. The sediment for the fans was probably supplied by a fluvial source to the north-west. Intra-basinal relief within the basins strongly influenced the initial development of the fan system but was later swamped by sedimentation. Only the Waddington Fell High remained present throughout deposition: the "low-seeking" turbidite sediments of the Pendle Grit Formation pinch-out over this structure. A period of uplift or eustatic sea-level fall at the end of Pendle Grit deposition resulted in the development of a minor unconformity on the southern margin of the Askrigg Block and across reactivated intra-basinal highs. This unconformity heralds a major change in the palaeogeography of north-west England and the beginning of Grassington Grit Group deposition. The fluvial clastic input moved eastwards, supplying sediment directly into shallow water on the Askrigg Block. This resulted in rapid progradation of a coarse clastic dominated braid-delta system over the Askrigg Block and, subsequently, out into the Bowland Basin. Water depths still increased rapidly across the fault controlled boundary between these two palaeogeographic features and this led to a change in the depositional processes on the braid-delta system. The resulting differences between Grassington Grit Group facies sequences across this palaeogeographic boundary form the basis for recognition of two Formations, namely the Grassington Grit and Warley Wise Formations. Detailed sedimentological study of the sand-rich fans in the Pendle Group shows that they are dominated by in-channel deposition: lobes and basin plain deposits are very rare. A channel hierarchy has been recognised in the fan sediments, based on the presence of erosion surfaces of different magnitude and extent. First-order erosion surfaces bound channel-complexes up to 1000m in width and 100m deep. These features were cut by infrequent, high energy turbidity currents. They were filled by progradation of a coarse-grained turbidite sand-body deposited from smaller, more frequent turbidity currents trapped in the first-order channel. During this process, second-order channels were cut and filled in the prograding sand-body. Individual beds within the fan system provide evidence for lateral migration of turbidity currents during deposition and also for prolonged flow events. The flow mechanics of such flows are qualitatively examined and their evolution with time and space over the fan system is discussed. A new facies model for sand-rich fans is presented, based on the sedimentological features seen in the Pendle Grit Formation. The El, basin-fill sequence was buried to several kilometres depth by end early Westphalian times. It then underwent rapid uplift. The paragenetic sequences in sandstones from this sequence are related to the maximum burial depth and the amount of subsequent uplift: deeply buried sandstones developed illite cements and, if affected by meteoric flushing during uplift, also have extensive pore-filling kaolinite. This relationship allows qualitative predictions of the reservoir quality of the Ei, sandstones to be made from an estimate of their burial histories.

The general thesis aim was to establish geometric criteria to distinguish between folds formed in unlithified sediment and lithified rock using dip isogon analyses on folds in sediment, lithified rock, migmatites and model materials. The methods involved connecting points of equal dip and measuring layer thicknesses at these points to calculate fold classes and to understand class changes around the folded layer. The criteria were applied to the Bude Formation folds and confirmed that the slump folds developed in sediment, but that also the Variscan tectonically-generated ‘upright’ chevron folds developed in sediment. ‘Inclined-to-recumbent’ chevron folds exhibit characteristics of folding in interbedded sediment and rock, suggesting that Variscan deformation affected the formation during lithification. The methods can be used to determine compressional structural evolutions with respect to lithification in other basins. The specific thesis aim was to study the sedimentary and structural evolution of the Late Carboniferous Bude Formation, Culm Basin, SW England. New sedimentary structures identified in the formation include: centimetric-scale muddraped ripple laminations; decimetric-scale mud-draped and non mud-draped troughs; and metric-scale tabular cross-stratification. The sedimentary structures, plus analyses of palaeoflow indicators, ichnofabrics and geochemistry, suggest that the formation records a mixed depositional environment, with fluctuating base levels and mainly fresh-to-brackish water conditions in a lacustrine or possibly marginal-marine setting. The map work revealed decametric-scale local structures in the Black Rock foreshore that formed prior to chevron folding. The basin-scale Widemouth South Fault (WSF) juxtaposes the Bude and Crackington formations that are separated stratigraphically by 300 m. The movement along the WSF is considered using three structural models from the deformation accommodated to its north and its south. Although no model holds fully, the Freshney et al (1972) ‘late’ normal-faulted Widemouth South Fault model is the most plausible, suggesting that the Culm Basin accommodated progressive compressional deformation prior to extension.

This study focusses on the production of mesoscale convective systems (MCSs) close to the intertropical discontinuity (ITD), including their associated dust uplift processes and representation in global and high-resolution, limited-area models. Findings from this work include a detailed description of the synoptic-scale meteorology important for the formation of a large, rare Saharan MCS and the spectacular dust plume which it created in June 2010. Results are presented from a high resolution simulation of this event using the Weather Research and Forecasting (WRF) model. Important dynamical processes which govern the triggering and development of the MCS are discussed as well as the mechanisms for dust uplift with which it is associated. Also highlighted from the simulation is the strong dependence of simulations on initial conditions and the disagreement at particular times between some operational analysis and reanalysis products (referred to here as (re)analysis products). (Re)Analyses are ostensibly representing the atmosphere at the same time and with the same observations as each other. Despite this, disagreement with respect to low-level moisture distribution between (re)analyses is shown to be large at times. Disagreement is as a result of different representations of the West African monsoon (WAM) flow and is greatest during the retreat after a northward excursions. It is also found that extreme disagreement events are linked to the occurrence of rainfall and anomalously high aerosol optical depth (AOD) values north of the zonal-mean ITD (ITD©). The seasonal patterns of rainfall in the Sahara and disagreement between (re)analysis products are shown to be similar, suggesting a link between the occurrence of convective storms and the representation of the West African Monsoon. There is also a spatio-temporal connection between anomalous rainfall events and anomalously high AOD values. Analysis of the synoptic-scale meteorology reveals a statistically significant 925 hPa geopotential dipole present during extreme rainfall events. This has been used to produce a preliminary version of an anomalous rainfall in the Sahara (ARS) index.

If the effects of landslides are to be mitigated and avoided then the causes of landslide activations – and re-activations – must be better understood. The most common subsurface property change in the lead up to rainfall-triggered landslide activation is the moisture content of slope material and associated pore water pressure rises and/or consistency changes. Landslide early warning systems have been developed which observe and monitor characteristic slope properties in advance of activation and give advanced warning of imminent slope displacement. This PhD thesis analyses and presents the results of a four and a half year monitoring campaign of a periodically active inland landslide by – among other methods – a geoelectrical monitoring system called Automated time-Lapse Electrical Resistivity Tomography (ALERT). The ALERT system was trialled on a landslide system located within the Early Lias of North Yorkshire and the suitability of the system for landslide monitoring assessed. The products of the geophysical monitoring campaign range from discrete resistance measurements on the landslide to a four-dimensional, high-temporal resolution dataset which is interpreted in terms of hydrogeological processes. Temperature corrected resistance results of the geoelectrical monitoring system reveal that the system responds very well to rises and falls in piezometric levels and seasonal trends of soil desiccation during warmer, drier months and crack annealing and slope soil moisture accumulation in response to wetter periods. The existence of threshold slope moisture contents, and hence electrical resistances/resistivities, above which the slope activates are not observed in resistance/resistivity results most probably due to the complex nature of the landslide system, the system resolution and a number of physical slope processes taking place. However, trends in precursory soil moisture dynamics during the period leading up to earthflow activation are apparent in temperature corrected resistance results. Time-lapse model resistivity was converted to gravimetric moisture content through laboratory calibration of soil electro-petrophysical properties of each active lithological formation. Seasonal moisture content trends confirm system sensitivity to slope moisture content. However, lower moisture contents than were observed in the field indicate the need for higher resolution, intra-landslide ERT data to make the hydrogeology of landslides more apparent.

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Integrated analysis of channelised fluvial sandbodies and their relationship to surrounding fine-grained floodplain fines enables interpretation of avulsion style and its links to allogenic and autogenic controls on stratigraphic architecture. A fundamental gap in our knowledge still lies in predicting the distribution and connectivity of channelised sandbodies generated via avulsion in the stratigraphic record. This thesis presents a study of two comparable high-quality fluvial successions; the upper Cretaceous Blackhawk Formation of the Wasatch Plateau, Utah, U.S.A, and the middle Jurassic Ness Formation of the Brent Field, North Sea, U.K. The aim of this research is to combine the use of aerial photographs, spatial statistical analysis (Besag's L function, lacunarity), fieldwork, and core to investigate the spatial distribution, geometry, stratigraphic architecture, and connectivity of channelised fluvial sandbodies. The data attained from this study will enhance understanding into the way in which fluvial environments operate through time, and build upon existing models of fluvial stratigraphic architecture. Analysis of measured section data from both case studies identified environments associated with wave-dominated delta plain deposition. Localised stratigraphic architecture reveals three styles of channel avulsion: avulsion by incision, avulsion by progradation and avulsion by annexation. Spatial statistical analysis reveals three styles of stratigraphic channel distribution: channel clustering, compensational stacking, and spatial randomness. Sandbody size and distribution, and the character, vertical stacking and abundance of lithofacies and palaeosols (entisols, inceptisols, histosols) differs locally within the two formations, however such variations are not consistent over basin-wide scales. These findings do not conform to existing models of alluvial architecture which typically relate such stratigraphic patterns to allogenic controls. These results suggest that deposition took place in the absence of or independent from any variation in external basin boundary conditions (e.g. sea level, tectonics and climate) and thus may be primarily controlled via autogenic responses such as avulsion.