North Osteroy comprises autochthonous and para-autochthonous basement which has been reworked during the orogenic development of the adjacent Bergsdalen and Bergen Arc nappes. The divisions of the basement, the Southern and Northern Gneiss Units, are composed of acid gneisses, paragneisses, migmatites, orthoamphibolites and granites. Three sedimentary complexes are identified, the first (circa 1500 Ma.) resembles the Fjordane complex. The second is correlated with sediments in the Bergsdalen Nappes (older than 1000 Ma.), and with the Samnanger complex in the Bergen Arcs. The third sedimentary sequence is the Ashgillian, Holdhus sequence of the Bergen Arcs. The rocks of the Southern Gneiss Unit are derived from, and emplaced over, the Northern Gneisses during four deformations, each of which is separated by a sedimentary interval. The deformation involves 'mylonitic' processes acting at high temperatures and high strain rates. The first deformation forms part of the Svecofennian orogenic cycle. The second and third form part of the Sveconorwegian cycle and produce folds with north-easterly trending axial traces. The third is responsible for the emplacement of the primary Bergsdalen Nappes and contrary to current opinion these Nappes are thought to root in the south east. The final deformation is part of the Caledonian orogenic cycle and involves the development of the Bergen Arcs and their emplacement over the Bergsdalen Nappes. In the early stages of this cycle, structures formed on an east-north-east Bergsdalen trend, but later, non-cyclindrical folds with north-westerly trending axial traces developed, giving rise to the Bergen Arc trend. Of the two deformations which produce the Bergen Arc and Bergsdalen Nappes, the Sveconorwegian event is the more important. The interpretation of the geology of N. Osteroy and consideration of its relationships to adjacent regions allows a new plate tectonic interpretation of Western Norway.

A complex transitional zone within river-estuary systems exists between fully-fluvial and fully-tidal conditions. This zone varies both spatially and temporally across a range of scales. The resultant sedimentary transport and depositional characteristics are, at present, poorly understood and a robust model that links processes to products across this complex zone is presently lacking. Process-product relationships were investigated in two distinctive tidal-fluvial systems: the high fluvial flux mesotidal Columbia River estuary (USA), and the smaller fluvial flux macrotidal River Severn (UK). Spatially and temporally distributed three-dimensional flow and bed morphology data within the two transitions were coupled to sub-surface geophysical and core information. High resolution bathymetric measurements collected within the Columbia River estuary transition zone allowed investigation of the variations in bedform and bar morphology. The dominant fluvial flow steers asymmetrical bedforms around local barforms, decreasing in size with increasing tidal influence. Barforms commonly have an apparently tidally-influenced lobate planform, however, investigations around a single bar indicated a fluvial origin, with tidal modification restricted to smaller-scale bedforms. Deposition within the River Severn appears fluvial, but the presence of a large tidal bore and strong flood tide is shown to hinder larger scale meander bend migration processes, also resulting in characteristic soft sediment deformation within bar deposits. The deformation may be important for palaeogeographical system reconstruction as tidal bores only form under limited conditions. Investigations within these two very different systems reveal that both are fluvially-dominated, but with some tidal influence. Although the barforms and surrounding bedforms appear to be fluvial they contain important, although subtle, evidence of the tidal nature of the system. This may be spatially limited and could be hard to detect in both cores and/or geophysical measurements. Careful analysis of the smaller-scale features of ancient lowland fluvial systems is required to observe evidence of this subtle tidal influence.

This thesis explores the nature of river dunes in unsteady conditions. River dune research has two main philosophical approaches that are necessitated by the nature of dunes; they are individually dynamic features emergent from the interaction between flow and sediment transport, whilst this dynamism is restricted by a mixture of instantaneous and historical flow and sediment boundary conditions. This thesis has applied both philosophical approaches to the investigation of river dunes in unsteady conditions and highlights key areas where flow and sediment processes at the laboratory scale overlap that of the larger scale river, such as in the suspension of sediment, and importance of velocity profile shape on dune shape. Normalising the downstream velocity with shear velocity was repeatedly found to simplify and explain the fluid processes over dunes across a range of conditions and indicates that the dominant processes controlling dune shape and sediment mobility are hydraulically smooth, despite hydraulically rough grain sizes. The existence of a turbulent wave over dunes reduces the magnitude of flow velocity that reaches the bed and effectively changes the grain Reynolds number. This turbulent flow structure was extensively measured in this thesis, with detailed instantaneous flow velocity measurements, across a range of flow conditions over fixed bedforms with the use of Particle Imaging Velocimetry. This also revealed that the well-known equilibrium turbulent flow structure over dunes is dramatically altered when in transient flow-morphology conditions. It was found that the wake and stacked wake, changes location and intensity with flow depth and discharge, and that reattachment length is strongly related to U/u* as measured at the dune crest. This research provides descriptions of the causal mechanisms behind many bedform adaptions to flow unsteadiness, such as the formation of humpback dunes in high shear stress conditions. A second set of laboratory experiments explored the mean scaling of dunes with a mobile bed in a recirculating flume. The mean velocity profile shape was adjusted to move the point of maximum downstream velocity toward the bed, whilst keeping depth and depth averaged velocity- two variables used in almost all bedform stability diagrams, the same. It was found that dune height scaled with bed shear stress in a parabola, whilst dune wavelength scaled linearly. This indicates that dune height is primarily controlled via flow separation and dune wavelength scales most well is shear velocity and grain size (i.e. sediment transport lengths). Lastly, dunes were measured in the field during the falling leg of the monsoonal wet season floods on a section of the Mekong River in Cambodia. The river bed consisted of large dunes with superimposed bedforms. The geometry of the large dunes showed no relationship with the hydraulic conditions present; however the secondary dunes size responded to the variations in flow depth. All large dunes migrated at a constant rate, despite variation in height, and it was hypothesised that the superimposed bedforms provided any excess sediment for the host dune migration. Large dune height was half that predicted from empirical equations using flow depth. Variations in suspended sediment did not match those predicted via the Rouse number, instead, plotting U/u*, across variations in discharge and depth showed a good relationship with suspended sediment concentration. This relationship between flow structure and suspended sediment, with the concurrent variation secondary dune size indicated that the large dunes were depth limited. This is despite the consistent presence of secondary dunes at the crest of the host bedform or strong free surface interaction and suggests that dune height in rivers with superimposed bedforms is controlled by the existence of superimposed bedforms.

The distribution of soil microfungi in the successive ecological zones of eight dune systems on the British coast was investigated with special reference to the acid system at Studland and the alkaline system at Sandwich. A number of direct and indirect fungal isolation methods were used and a new modification of the soil impression technique was developed for a comparative estimate of the amount of mycelium in dune soils. Qualitative and quantitative changes in the fungal population were studied in relation to the soil type, the soil profile and the vegetation. A succession of species was found to occur across the dune systems from the pioneer communities of the foreshore to the climax or sub-climax communities of the fixed dunes. The existence of distinct mycofloras in the acid and alkaline soils and the development of a microfungal profile were also demonstrated. The root surface fungal floras of Ammophila arenaria and Carex arenaria were examined at various stages of the dune succession and found to vary with soil type, reflecting the succession of "free" soil fungi. The dune soil fungal flora appeared from this investigation to be an active and relatively rich community, exhibiting an ecological succession and species associations on a scale comparable with that of the higher plants.

The integration of several industry and scientific 2D seismic surveys with various well data allowed for the first time a detailed analysis of the sedimentological, stratigraphic and architectural changes recorded during syn- to post-rift transitions on passive margins. The Northwest Iberia margin and its conjugate margin of Newfoundland formed the basis for an interpretive model. Comparison with the South Australia�East Antarctica conjugate margins enabled hypothesis testing and premise refinement. The breakup unconformity concept is revised and a more comprehensive term is proposed for the stratigraphic surface recording the transition between syn- and post-rift: the lithospheric breakup surface. This new term: a) discriminates between continental crust breakup and complete lithospheric breakup as verified in several magma-poor margins, and b) takes into account the different character this surface can show according to its position on the margin. The concept of a breakup sequence is proposed as a sedimentary sequence showing a distinct architecture to strata deposited prior to the lithospheric breakup event. The breakup sequence records the depositional changes occurring across the lithospheric breakup surface due to lithospheric adjustments triggered by lithospheric breakup. Contourites were identified for the first time as being associated with lithospheric breakup, supposedly being triggered by the lithospheric plate in-plane stress release occurring at the time of lithospheric breakup. Consequently, it is proposed that contourites can be used as an indicator for established lithospheric breakup. On the East Antarctica margin, a surface usually dated as mid Eocene to early Oligocene by comparison with the conjugate South Australia margin, is dated as latest Maastrichtian�earliest Palaeocene using data from IODP Site 1356. This new date suggests that the surface is a lithospheric breakup surface, which can explain its generation and the overlying strong contouritic deposition.

The Toutle-Cowlitz River system experienced dramatic landscape disturbance during the catastrophic eruption of Mount St Helens on May 18, 1980. The eruption was triggered by a 2.5 km3 debris avalanche which buried the upper 60 km2 of the North Fork Toutle River catchment to an average depth of 45 m and obliterated the surface drainage network. Subsequent channel response on the debris avalanche, dominated by incision and widening, has delivered significant quantities of sediment to downstream reaches where resultant deposition has reduced channel capacity and heightened flood risk. Estimates of future sediment yield from the upper North Fork Toutle River are therefore required to inform development of sustainable options for long-term flood risk mitigation. Previous estimates have been based on extrapolation of post-eruption trends in sediment yield and channel network evolution, but the divergent predictions reported in a number of studies have clouded effective decision-making regarding long-term sediment management. This study therefore uses a numerical, landscape evolution model (CAESAR-Lisflood) to make long-term forecasts of sediment yield based on process simulation rather than extrapolation. A suite of forecasts of cumulative catchment sediment yields up to 2100 are produced using scenario-based model runs designed to account for uncertainty associated with the hydrological impacts of climate change and the model coefficient for lateral mobility. The forecasts fall in a narrow band +/-20% of the mean that lies between two previous estimates derived from the extrapolation of post-eruption trends. Importantly, predicted trends in future annual sediment yield are predominantly linear, although some limited decay is evident for runs in which modelled channel lateral mobility is lower. Sustained sediment production in the upper North Fork Toutle River is found to result from persistent bank erosion and channel widening. These findings cast doubt on the applicability of negative exponential decay functions based on the rate law to characterise post-disturbance sediment yield when lateral rather than vertical adjustments dominate channel evolution. Moreover, forecast trends in future sediment yield suggest that it may not be possible to manage future sediment-related flood risk along the lower Cowlitz solely by retaining sediment in the upper North Fork Toutle River catchment.

Fluid venting structures are used to evaluate fluid migration in the subsurface and vertical changes in their morphology reflect variations in the intensity of fluid leakage through time. This research uses high-resolution 3D seismic data from the Lower Congo Basin offshore Angola to analyse complex assemblages of vertically-stacked fluid venting systems in the Middle Miocene to Holocene succession. Individual fluid-venting structures that form part of vertical venting systems include conical pockmarks, fluid related shallow depressions with flat bottom, chimney structures and positive high amplitude anomalies (PHAAs). Detailed seismic interpretation reveals for the first time that chimneys and PHAAs have a variety of plan form geometries (circular through to linear) within a given vertical succession of fluid venting structures. Linear chimneys are often associated with PHAAs which are interpreted as deposits of methane-related carbonate. The geometry and depth of depressions associated with fluid venting structures are used to infer relative rates of fluid flux or intensity of the fluid eruption. This classification scheme is as follows; linear PHAAs and conduits (slow fluid venting), sub-circular PHAAs and shallow depressions (slow to moderate rates of venting), pockmarks (fast rates of fluid venting). Two new types of pockmarks are identified based on the architecture of the sediments which infill them. They include advancing pockmark arrays and nested pockmarks. In contrast to normal pockmarks which are stacked vertically, successions of nested pockmarks and advancing pockmark arrays are laterally offset and migrate laterally, typically downslope. The reactivated craters of advancing pockmarks erode the downstream margin of preceding and underlying infill sequences whilst the infill sequence of nested pockmarks migrate gently downslope but without eroding the underlying and preceding infill sequence. Nested pockmarks and advancing pockmark arrays are confined to inclined surfaces. Downslope migration is a product of the interplay between slope inclination, sedimentation rate and bottom current activity. The trails of nested pockmarks and advancing pockmarks cluster above the axis of gas-bearing turbidite channels. PHAAs, chimneys, a present day bottom simulating reflector and negative high amplitude pockmark infills also occur in these areas and pockmarks occur above crestal faults which root in underlying rollover anticline. This implies the fluid source was derived from depth in the turtle anticline structure. The presence of negative, high-amplitude pockmark infills may suggest the fluid source was gas. A detailed spatial analysis and characterization of fluid venting structures on successive horizons in the middle Miocene to Holocene succession indicates that their distribution and type are affected by tectonic structures and vertical changes in the nature of the host sediments. Linear chimneys occur vertically below Linear PHAAs. The former are occur within the polygonally faulted interval whilst the later occur at the top of above the polygonally faulted interval. They tend to cluster in parts of the basin where the orientations of polygonal faults are strongly perturbed such as around salt diapirs and in salt-withdrawal synclines. Both linear venting structures are interpreted to post-date polygonal fault growth. Linear chimneys and linear PHAAs both have a close spatial and geometric relationship with PFs and deeper extending salt-related faults. The parallel relationship between linear venting structures and adjacent faults (salt or compaction related) are attributed to development and alignment of vertical hydraulic fractures (vertical conduits for linear chimneys) in the local fault induced stress field which subsequently provides fluid migration pathways. A model of vertical fluid migration through the polygonally faulted interval is proposed it involved initial fault-bound trapping, sealing and overpressure beneath an impermeable horizon in the lower part of the PF tier in the early stages, and vertical breaching, hydraulic fracturing and vertical fluid rise through the upper part of the tier in the later stages. Vertical changes in the morphology and type of fluid venting structures occur across small vertical transitions which reflect changes in gross lithology from fine-grained hemipelagites to chaotic and heterogeneous mass transport deposits (MTDs). A linear zone of positive high amplitude anomalies, referred to as a linear venting network, transitions to an array of elongate-to-sub circular shallow depressions with flat bases or conical pockmarks at the upper surface of MTDs. Further changes occur above MTDs where honeycomb pockmarks, so-called based on their hexagonal-shaped perimeter which coincides with polygonal fault intersections, exist. In these cases vertical changes in the type of fluid venting structures are attributed to contrasting patterns of mechanical failure in different sediment when subject to fluid overpressure. Although individual linear chimneys and PHAAs post-dating polygonal growth are strongly affected by the location and orientation of PFs those which precede polygonal fault growth such as pockmarks can affect the orientation of PFs. For example deep pockmark craters with the steepest sidewall inclinations coincide with overlying concentrically aligned PFs yet those which are shallower and have gently dipping sidewalls coincide with more isotropic PF patterns. This suggests that the topographic relief of pockmark craters or compaction above craters of certain depths perturb the stress state within sediments where polygonal faults form. This thesis has demonstrated that seismic interpretation of vertical successions of different types of fluid venting structures can be used to reconstruct spatial variations in the intensity of fluid flow at different stages in the evolution of basins.

The Carpathian Mountains in Romania hold around 150-200 glacial lakes and traverse a region where there are considerable environmental concerns. Despite a long tradition of palaeoecological study in the region, to date relatively little has been published on the alteration of their sediment characteristics due to recent human-induced environmental impacts. This research project has investigated the physical characteristics, the mineral magnetic properties and the trace metal levels of sediment cores from ten selected lakes in the southern and northern Carpathians of Romania in order to evaluate the possibility of using these lakes’ sediment as records of recent human impacts and, in particular, trace metal deposition. Laboratory analysis has included sediment bulk density measurements, loss-on-ignition and laser diffraction based particle size determination, environmental magnetism and geochemical (ICP-OES) analysis. A single core from one of the south lakes (Lacul Capra) was radiometrically dated. There were distinct variations in catchment and lake area, the ratio of catchment area to lake size and in lake depth between both regions. The physical characteristics of the lake sediments demonstrated similar trends in their down core profiles in both regions, although the lakes from the south demonstrated a larger particle size range than those in the north. The environmental magnetism of the sediment cores demonstrated common characteristics in surface or near surface peaks magnetic concentration, but there were variations in the magnitude of the concentrations between both regions. The surface increase in concentrations indicated the influence of the atmospheric deposition of particulate deposition associated with fossil fuel combustion and vehicle emissions, but it may also be influenced by microbiological activities within the lakes’ sediment. The geochemical analysis (EFs and down-core profiles) showed that the same trends in metal concentration were repeated across the lakes in both regions, but the south lakes displayed higher peak in Pb and Zn concentrations, than were found in the north lakes. The research project has demonstrated the likely influence of atmospheric particulate deposition on the sediments of the lakes from both regions and it has demonstrated spatial and temporal variations in trace metal levels in the lake sediments. It has thereby provided a preliminary database and an overview of palaeolimnological information in two regions of the Romanian Carpathians. Thus, it provides an addition to the records of recent pollution in Romania and a gateway to further investigations in the area of recent palaeoenvironmental change in this region.

A volume of 3D seismic data has been used to study the interplay of Cenozoic structural deformation and its relationship to sediment deposition offshore South-West Nigeria. The 3D survey encompasses an area that includes sediments derived from both the Niger Delta in the east and the Benin Embayment to the north. Sediments derived from the Niger Delta are comprised of deep water sands and shales deposited in channel levee turbidites and hemipelagic sheets, whilst those from the Benin Embayment are primarily fine grained and encompass large scale levees. The study area can be divided into two vertically separated tectonic domains, which are divided by a detachment interval. The vertical separation occurs at a level which is coincident with an apron of mass transport deposits which extends beyond the limits of the data, this complex is interpreted to have been deposited at the end of the Cretaceous. The Cenozoic interval has been modified by gravity driven tectonic activity which has resulted in two structurally dissimilar regions, which are separated by a strike slip fault zone. To the west of this strike slip fault zone is a region of primarily compressional deformation, to the east the majority of the deformation is extensional. The structural styles recognised, extension, compression and strike slip motion have been analysed to establish the timing and the causes of the deformation. The influence of the sediment dispersal upon the location and timing of the tectonic deformation has been inferred indicating that structural deformation in this region pre dates the onset of deposition from the Niger Delta. The deformation which occurred prior to the Niger Delta outbuilding was controlled by the sediment dispersal from the Benin Embayment and this earlier, sediment controlled deformation, has subsequently played a role in the modified gravity tectonics which has been observed.

Fluvial sediment transport is controlled by hydraulics, sediment properties and arrangement, and flow history across a range of time scales. This physical complexity has led to ambiguous definition of the reference frame (Lagrangian or Eulerian) in which sediment transport is anal- ysed. A general Eulerian-Lagrangian approach accounts for inertial characteristics of particles in a Lagrangian (particle fixed) frame, and for the hydrodynamics in an independent Eulerian frame. The necessary Eulerian-Lagrangian transformations are simplified under the assumption of an ideal Inertial Measurement Unit (IMU), rigidly attached at the centre of the mass of a sediment particle. Real, commercially available IMU sensors can provide high frequency data on accelerations and angular velocities (hence forces and energy) experienced by grains during entrainment and motion, if adequately customized. IMUs are subjected to significant error accu- mulation but they can be used for statistical parametrisation of an Eulerian-Lagrangian model, for coarse sediment particles and over the temporal scale of individual entrainment events. In this thesis an Eulerian-Lagrangian model is introduced and evaluated experimentally. Absolute inertial accelerations were recorded at a 4 Hz frequency from a spherical instrumented particle (111 mm diameter and 2383 kg/m3 density) in a series of entrainment threshold experiments on a fixed idealised bed. The grain-top inertial acceleration entrainment threshold was approxi- mated at 44 and 51 mg for slopes 0.026 and 0.037 respectively. The saddle inertial acceleration entrainment threshold was at 32 and 25 mg for slopes 0.044 and 0.057 respectively. For the evaluation of the complete Eulerian-Lagrangian model two prototype sensors are presented: an idealised (spherical) with a diameter of 90 mm and an ellipsoidal with axes 100, 70 and 30 mm. Both are instrumented with a complete IMU, capable of sampling 3D inertial accelerations and 3D angular velocities at 50 Hz. After signal analysis, the results can be used to parametrize sediment movement but they do not contain positional information. The two sensors (spherical and ellipsoidal) were tested in a series of entrainment experiments, similar to the evaluation of the 111 mm prototype, for a slope of 0.02. The spherical sensor entrained at discharges of 24.8 ± 1.8 l/s while the same threshold for the ellipsoidal sensor was 45.2 ± 2.2 l/s. Kinetic energy calculations were used to quantify the particle-bed energy exchange under fluvial (discharge at 30 l/s) and non-fluvial conditions. All the experiments suggest that the effect of the inertial characteristics of coarse sediments on their motion is comparable to the effect hydrodynamic forces. The coupling of IMU sensors with advanced telemetric systems can lead to the tracking of Lagrangian particle trajectories, at a frequency and accuracy that will permit the testing of diffusion/dispersion models across the range of particle diameters.