The Caspian Sea is the world's largest closed body of water, and it has a number of unique features, not least, the considerable fluctuations in water level during the 20th century. This water level dropped by 3 m from 1929 to 1977, increased rapidly by 2.6 m during thetwo decades following, and from 1995 a slow rate of change continues. It is likely that the underlying causes of these water level changes are the human activities in the Caspian Sea Basin but literature shows that climate change also had a significant effect. Moreover, these sea level changes occur in a region with a high intrinsic level of seismic activity due to its tectonic setting. Since the sea level fluctuations represent very large scale changes in the loading of the Earth's crust, it seems likely that they are responsible for aspects of the overall seismicity. This is analogous to the problem of Reservoir Induced Seismicity, although even the largest reservoirs are tiny compared to the Caspian Sea. The research reviews the available data to create a reliable database of seismic events in the desired timeframe and location. It was observed that there was a correlation between the Caspian Sea level fluctuations and changes in regional seismicity. Further analysis indicated changes in the b-value of the Gutenberg-Richter Relationship that had an inverse correlation with water level fluctuations, demonstrating that RIS effects are significant. Through statistical examination of the earthquakes listed in the catalogue, the research attempted to find events which could possibly be induced earthquakes. Another large scale effect of the Caspian Sea level changes is investigated on its coasts where the beach profiles were affected by these changes. This sea is a unique laboratory for studies related to sea level rise and several studies have been performed by other researchers on the northern and western Caspian Sea coast. The southern coast, however, has not been adequately explored, thus this research aimed to investigate this part of the coastline. Three field surveys were made along 700 km of the southern coast. In addition to shore sediment sampling, land forms were mapped. Also, deep sediments were sampled by divers along profiles at right angles to the coast at 5 depths up to a depth of 10 m, and hydrographic profiles were surveyed. Laboratory tests were performed on the collected sediment samples. Several classifications were generated based on different factors, and finally, the southern Caspian Sea coast was classified into four categories with respect to their behaviour in response to sea level change. This study investigates the cause and two large scale impacts of the changing water level in the Caspian Sea, and provides a database for future studies. The result can be applied to predict future problems if the water level of the Caspian Sea continues to show considerable changes.

The enhanced warming effect possibly due to anthropogenic green house gas emissions has led to the derangement of global climatic mechanisms (especially at the interannual scale). This has led to the disturbances to the equilibrium of the Earth System and the interconnected self-regulatory processes. Terrestrial vegetation takes an active role in the regulation of the equilibrium of the Earth System by the processes of resistance and resilience. Whilst comprehensive and extensive modelling studies that investigate the effects of climatic change in terrestrial systems have been undertaken, few investigations have focused on the change and evolution in these systems from a holistic geophysiological perspective. In the first part of this thesis, econometric time-series modelling techniques were applied to National Oceanographic and Atmospheric Administration Advanced Very High Resolution Radiometer derived Normalized Difference Vegetation Index data sets in order to evaluate the responses of terrestrial South American vegetation to the interannual El Nifio Southern Oscillation climatic perturbations. Lags between vegetation response and the El Nifio Southern Oscillation perturbations are identified and quantified. The results indicate that the terrestrial vegetation loses its sensitivity to El Nifio Southern Oscillation perturbations in the post 1993 period, leading to the hypothesis that the terrestrial system maybe showing a Gaian behaviour that would enable homeostasis in the system of concern. The null hypothesis of this was tested using a stochastic Auto Regressive Integrative Moving Average model, which further strengthens the argument put forward by the hypothesis. Further comprehensive analysis was performed by using the Hybrid version 4.1, a mechanistical model of vegetation dynamics to test the effects of varying changes in the phase and amplitudes of the El Nino Southern Oscillation on terrestrial vegetation. Simulations of different interannual El Nino Southern Oscillation climatic scenarios under varying trends for increases in atmospheric C02 concentrations confirm the possibility of such a homeostatic property in the terrestrial vegetation system within its geophysiological limits.

The Dalradian Supergroup is divided into four groups, the uppermost of which is the Southern Highland Group (SHG). To date there are few sedimentological data that pertain to the SHG. In this thesis new field, petrographic and geochemical data are provided for the SHG and a model for its evolution outlined. The Killin and Aberfoyle areas together provide one of the most complete sections through the SHG. New sedimentological data from these sections are used here as a basis on which to build a correlative stratigraphy for the entire SHG basin which extents from Banff in NE Scotland southwestward into N. Ireland. The sediments of the SHG and the underlying Tayvallich subgroup of the Argyll Group change are dominantly turbiditic in character. They change stratigraphically upward from predominantly carbonate turbidites to siliciclastic turbidites. Volcaniclastic units are present, especially in the lower parts of the sequence. The volcaniclastic sediments document distal fall out of ash derived from plume-related volcanoes. The sedimentary sequences record the history of an evolving basin developed on the southern margin of Laurentia during the opening of the Iapetus Ocean. This history spans sedimentation during initial active rift faulting with rapid subsidence rates through to a drift stage with sedimentation along a passiv.e margin marked by thermal subsidence. Those parts of the sequence deposited on oceanic crust have been removed by later tectonic activity. Using present day geographic co-ordinates, the long axis of the basin was orientated NE-SW with the majority of the sediments derived from the N and NW and deposited by sediment gravity flows in a slope apron or a submarine ramp environment. The source terrain comprised mainly granitic basement-type rocks with abundant quartz veins. However parts of the sequence show an igneous component with the geochemical signature of within-plate, plume-type basalts. Geochemical data show that the major change in provenance was temporal rather than geographic. Geochronological data derived from detrital minerals suggest that erosional systems in the hinterland were exposing increasingly old, probably Archaean basement, rocks as SHG deposition continued.

Traditionally, governance of the marine1 environment has been state driven dominated by a top-down approach to management. Recently, however, management has evolved into a more participatory, bottom up regime in an aim to address the historical failures associated with traditional marine management. This study seeks to establish the potential role of citizenship specific to the marine environment. The founding rationale of the research is the suggestion that with a greater level of public involvement and responsibility, marine management could be developed at a more sustainable, long-term level. Following an extensive systematic literature review examining the role of citizenship in environmental management, and its potential applicability for the marine environment, a theoretical conceptual model of marine citizenship was generated. Through telephone interviews, the potential role of marine citizenship in marine management and policy delivery in the UK was evaluated. Results identified numerous factors with the potential to influence public expression of marine citizenship and these were further categorised into the key themes of education and personal attachment to the marine environment. In order to examine these issues further, two thematic case studies were designed to further evaluate their role in the inculcation of marine citizenship. It was found that current levels of marine education are insufficient, while sense of public connection with the marine environment was found to be low. Both factors were observed to be in need of improvement in order to engender a societal sense of marine citizenship in the UK. Synthesis of the results furthered the generation of the first working model of marine citizenship and established the necessary enabling factors required for successful expression of marine citizenship. In addition, specific management measures and recommendations for successful promotion of marine citizenship were defined. The research concluded given that a movement towards enhanced public engagement in the process has been identified as the ideal situation for marine management, encouraging a sense of marine citizenship could be an effective delivery mechanism. Further to this, it was determined that, central to successful inculcation of marine citizenship is the recognition that its promotion will require considerable effort on the part of marine managers and governance bodies to address the current capacity issues associated with public engagement.

To predict the impact of future disturbances such a climate change and introduction of non-native species on ecosystems, it is important to understand how disturbances may affect community composition. This is inherently diffcult since species may be expected to respond differently to disturbances such as elevated temperatures or the introduction of a new species. Furthermore, since the species in an ecosystem are interlinked by energy, nutrient and information transfers, disturbances may be amplified or absorbed, depending on the nature of the disturbance and the resilience of the ecosystem. Some species have a disproportionate effect on ecosystem function and are often referred to as keystone species. By definition the loss of a keystone species causes a catastrophic change in community composition. Therefore, the identification of keystone species could help to target conservation efforts more effciently. A dynamical food web model, representative for a chalk stream (the River Frome, Dorset) was developed and manipulated. Changes in community composition and biodiversity were assessed. For the identification of keystone species each species node was removed in turn. Although impacts were found, particularly after the removal of important prey nodes and top predators, no catastrophic shift was observed and, consequently, no keystone species were identified. Impacts of species introductions were assessed by adding representative model species to the food web. The largest impact was observed after the addition of a small competitor at intermediate trophic level. The addition of a top predator had moderate impact, whereas no negative impact was found after the addition of a larger bodied species at intermediate trophic level. Possible impacts of climate change, specifically elevated temperatures, were assessed by increasing the metabolic rates of the species nodes. No impacts were found, when energy inputs were raised accordingly, but severe impacts, were observed when energy inputs were restricted. In general, the ecosystem was considered fairly resilient to most of the tested disturbances, possibly owing to the high natural variability of the community. The findings of current study suggest that rather than focusing conservation efforts on single species, the focus should be on 'keystone structures' that maintain high ecosystem resilience.

Plants are of fundamental importance to the structure, functioning and service provision of many ecosystems. However, herbivores can have negative ecological and socioeconomic effects on plant communities through consumption, trampling and alteration of nutrient cycles. In this thesis I address a particular herbivore-plant interaction: the grazing of plants in chalk river catchments, principally the submerged macrophyte water crowfoot (Ranunculus penicillatus ssp. pseudofluitans (Syne) S.D. Webster) and terrestrial pasture grass species, by flocks of non-breeding mute swans (Cygnus olor Gmelin, 1789). This research was carried out over two years in the River Frome catchment (Dorset, UK). Based on a meta-analysis of previous waterfowl grazing studies I show that waterfowl biomass density (kg ha-1) rather than individual density (ind. ha-1) is a better predictor of reductions in plant standing crop. Most studies to date have analysed such reductions using only individual densities, despite large between-taxa variation in waterfowl body mass, diet and intake rates. I quantified the abundance, species richness, evenness, flowering and dominance of the chalk river aquatic plant community in relation to biotic and abiotic factors during the growth-, peak-, and recession-phases of the growth cycle. The relative importance of herbivory, riparian shading, water temperature and distance downstream varied between different phases of the plant growth cycle, highlighting the importance of seasonal patterns in regulation of plant community structure. The River Frome swan population varied seasonally, being highest in the winter. The population was dominated by non-breeding adults and juveniles that lived in flocks. These flocks exhibited strong seasonal habitat switches between terrestrial pasture in winter and spring, and river in summer and autumn. I provided evidence that this switch was linked to the seasonal decrease in water velocity between spring and summer, which reduced the metabolic costs of river feeding and increased the relative profitability of aquatic food resources. I used a mathematical population model and an individual-based behavioural model respectively to explore two management options for the alleviation of the swan grazing conflict in chalk rivers: population control and habitat alterations. Population control measures, such as clutch manipulations, fertility control, culling or translocations, were predicted to be unsuccessful except at impractically high levels of management effort, due to the effects of immigration and high survival rates in offsetting removed eggs or individuals. Habitat alterations, in particular the narrowing of river channels to cause a local increase in water velocity and thus swan foraging costs, are more promising management options as they require lower management effort, are less ethically controversial, and address the fundamental reason why swans select their food resources, the rate of net energy gain (‘profitability’).

Thermal Coe-modified-Thellier (CMT) and microwave (MW) palaeointensity (PI) investigations have been conducted on the Permo-Carboniferous Great Whin Sill (GWS) of northeast England, the Tertiary dyke swarm from the Isle of Skye and rocks from the Eastern Australia Cenozoic igneous province. These results provide important new palaeointensity data for the global palaeointensity (PINT) database in sparsely covered time windows. The GWS complex comprises at least three temporally distinct phases of intrusive activity. Fifty-six samples split between two of these phases, dated at ca. 269Ma and ca. 294Ma, have been investigated. Rock-magnetic investigations indicate pseudo-single- domain (PSD) grain assemblage of magnetite, with Curie temperatures between 550[sup]°C and 560[sup]°C in most samples. On comparison, data from CMT and MW investigations could not be distinguished in terms of quality or their respective mean PI value. Combined CMT and MW results yield Virtual Dipole Moments (VDM) of 1.2±O.1x10[sup]22 Am[sup]2 and 1.6± O.2x10[sup]22 Am[sup]2 for the younger and older phases respectively. These results, when coupled with previous estimates within the PINT database, support the view that the geomagnetic field intensity was dominantly lower during the Permo-Carboniferous Reverse Superchron in comparison with the present day value. The Tertiary dyke swarm of Skye comprises basaltic and doleritic intrusions. Thermomagnetic results suggest that the dominant magnetic mineral is magnetite or low-Ti titanomagnetite, with Curie temperatures between 490[sup]°C and 570[sup]°C. Hysteresis data suggest that samples comprise a PSD grain size assemblage. Many samples carry two anti-parallel remanence components, but the secondary low temperature (100- 300[sup]°C) is unstable. A mean 2.2± 0.91x 10[sup]22 Am[sup]2 VDM is calculated for the ChRM between 300-550[sup]°C, from forty-three samples. Several basaltic lavas and intrusions were sampled and investigated from the Australian Cenozoic igneous rocks. Rock magnetic analysis indicates Ti-enriched titanomagnetite (TM[sub]70- TM[sub]50) as the dominant magnetic phase in all samples with pseudo-single domain characteristics. The primary titanomagnetite carries a stable single component magnetization. Comparable MW and CMT data combine to produce three mean VDMs; 4.7± 0.7x 10[sup]22 Am[sup]2, 2.9± 1.4x 10[sup]22 Am[sup]2 and 3.1± 1.7x 10[sup]22 Am[sup]2 for volcanic rocks dated at c.48Ma, 46Ma and 22Ma respectively. The low mean PI from both the British and Australian igneous provinces is comparable with results from contemporaneous rocks, documented in the PINT database, suggesting the early Tertiary field was weaker than that of the present day. Results from each of the sampled igneous provinces demonstrates comparability between the microwave and thermal CMT palaeointensity techniques. However, while the microwave method significantly shortens experimental time, no significant enhancements in data quality or success rates were achieved on the rocks investigated.

Volcano flank collapse events affect volcanic edifices where a range of different processes are at work. However, there is at least one mechanism of generating instability that may be present at all volcano collapse locations: increases of edifice pore fluid pressures from internal sources. The use of geomechanical classification schemes such as the Rock Mass Rating (RMR) show that a volcano can be considered mechanically weak and little more than a pile of granular material. Initial field work and laboratory testing demonstrated that it is possible to estimate volcanic rock-mass compressive ([sigma][sub]cm), tensile ([sigma][sub]tm) and cohesive (c) strength from the RMR using the power law relationships ([sigma][sub]cm = O.5161e[sup](0.0581*RMR), ([sigma][sub]tm = 0.0055e[sup](0.0744*RMR) and c = 0.0349e[sup](0.0649*RMR) . Simple analogue models using sand piles as scaled proxies for a volcano edifice demonstrate that internal gas pressure is a viable mechanism for promoting structural instability. Complementary two-dimensional limit equilibrium methods (LEM) confirm this effect, showing a clear reduction in edifice stability with increasing degrees of internal pressurisation. However, internal pressures in excess of 25 MPa are needed to reduce the Factor of Safety below unity, indicating this mechanism is unlikely to be the solitary contributor to sector collapse. Three-dimensional numerical modelling of edifice stability using FLAc[sup]3D provides a sophisticated means of undertaking a complex analysis of volcano instability caused by internal pressurisation. Five model geometries were examined over a pressure range of 0 to 20 MPa that allowed the sensitivity of gas pressure on structural stability to be assessed quantitatively. Significant reductions in stability were observed in all cases, with the most unstable modelled edifice possessing a combination of 'weak' foundations and shallow regional gradient. A key finding is that the instability observed in both the analogue and LEM results are replicated in the 3D numerical models, confirming for the first time the significance of internal (gas) pressurisation as a potential trigger mechanism for volcano flank failure.

Climate is one of the key variables driving ecosystems at local to global scales. How and to what extent vegetation responds to climate variability is a challenging topic for global change analysis. Earth observation provides an opportunity to study temporal ecosystem dynamics, providing much needed information about the response of vegetation to environmental and climatic change at local to global scales. The European Space Agency (ESA) uses data recorded by the Medium Resolution Imaging Spectrometer (MERlS) in red I near infrared spectral bands to produce an operational product called the MERlS Terrestrial Chlorophyll Index (MTCI). The MTCI is related to the position of the red edge in vegetation spectra and can be used to estimate the chlorophyll content of vegetation. The MTCI therefore provides a powerful product to monitor phenology, stress and productivity. The MTCI needs full validation if it is to be embraced by the user community who require precise and consistent, spatial and temporal comparisons of vegetation condition. This research details experimental investigations into variables that may influence the relationship between the MTCI and vegetation chlorophyll content, namely soil background and sensor view angle, vegetation type and spatial scale. Validation campaigns in the New Forest and at Brooms Barn agricultural study site reinforced the strong correlation between chlorophyll content and MTCI that was evident from laboratory spectroscopy investigations, demonstrating the suitability of the MTCI as a surrogate for field chlorophyll content measurements independent of cover type. However, this relationship was significantly weakened where the leaf area index (LAI) was low, indicating that the MTCI is sensitive to the effects of soil background. In the light of such conclusions, this project then assessed the MTCI as a tool to monitor changes in ecosystem phenology as a function of climatic variability, and the suitability of the MTCI as a surrogate measure of photosynthetic light use efficiency, to model ecosystem gross primary productivity (GPP) at various sites in North America with contrasting vegetation types. Changes in MTCI throughout the growing season demonstrated the potential of the MTCI to estimate vegetation dynamics, characterising the temporal characteristics in both phenology and gross primary productivity.

Chemical, textural, and isotopic heterogeneity within granitic magmas/rocks, and their extrusive equivalents, are common phenomena. This is to be expected since the source materials, from which the granitic magmas were created by partial melting, are themselves heterogeneous. Micro-sampling of feldspar crystals within granites has revealed complex internal Sr and Nd isotope variations thought to reveal subtle variations in the isotopic composition of the melt from which particular zones crystallised. These previous studies provide evidence of both macro-scale (regional) and micro-scale isotopic variation within granitic magmas. What is unknown is the scale and nature of chemical and isotopic variation occurring on the meso-scale (metre, decametre, hectometre). In this study, high-precision geochemical and isotopic (Sr, Nd, and O) data is obtained for spatially well-constrained samples, from three granitic intrusions from the UK, to study the scales over which isotope heterogeneities are preserved, and the maximum volumes of magma over which isotope and elemental homogenisation may have been achieved. This information provides important constraints on the physical and chemical characteristics of processes that occur during magma genesis, ascent, and emplacement. The regional-scale geochemical and isotopic heterogeneity in the Criffell pluton (SW Scotland) has been well documented and ascribed to 'incomplete hybridisation' between magmas derived from the melting of mantle and/or 'new' basic crust and metasediments. Sampling on the 10 to 100 m scale in this study demonstrates major-, trace- and rare earth element homogeneity between samples of similar petrography. Within the Dalbeattie Quarry granodiorite, subtle heterogeneity in initial ([sup]87Sr/[sup]86Sr)[sub]397 Ma compositions exist (0.70582 to 0.70615), between samples collected ~ 150 m apart. The small-scale heterogeneity is outside of analytical error (± 0.0001). [delta][sup]18O heterogeneity also occurs on similar small scales (~ 120 m), with values ranging from 8.9 to 10.7 %. The larger error on the [epsilon][sub]Nd(397 Ma) values do not allow any small-scale heterogeneity to be resolved. The geochemical and isotopic heterogeneity of the Cairnsmore of Fleet pluton, another Southern Upland granite, is also well known, and considered to be a result of similar processes to that of Criffell. This study demonstrates that the Cairnsmore granite is more petrographically variable in terms of grain-size, mafic/felsic mineral proportions, and accessory mineral assemblages over scales ranging between 100 and 350 m. The existence of more petrographic and geochemical heterogeneities on smaller scales suggests that homogenisation processes were less effective in this pluton compared to Criffell. On scales < 1 km, ([sup]87Sr/[sup]86Sr)[sub]392 Ma compositions and [epsilon][sub]Nd(397 Ma) values are essentially homogeneous. Forest Track samples PAHCF23 (0.70796) and PAHCF25A (0.70672) are ~ 1 km apart and can only just be distinguished outside of analytical error. However, [delta][sup]18O data demonstrate the existence of both regional-scale and locality-scale [delta][sup]18O heterogeneity on the 100 m, decametre and even cm-scale (8.3 to 9.7%0, error ± 0.1%0). The two main granite varieties of the Dartmoor pluton (SW England) are generally, homogeneous in terms of their petrography and geochemistry on 100 m, decametre, meter and even cm scale. However, isotope heterogeneity, outside of analytical error is shown to exist on even the cm-scale. The samples PAHD34A and P AHD34B, from Blackenstone Quarry, have ([sup]87Sr/[sup]86Sr)[sub]280Ma compositions of O.70949 and 0.71292 respectively, and were collected 50 cm apart. Samples PAHD35A and PAHD35B have ([sup]87Sr/[sup]86Sr)[sub]280 Ma compositions of 0.70960 and 0.71205, and were collected 100 cm apart. Variation in [delta][sup]18O and [epsilon][sub]Nd(280 Ma) values also exist. PAHD34A and PAHD34B have [delta][sup]180 compositions of 10.01 and 10.98 %0 (± 0.1%0), and SNd(280 Ma) values of -3.8 and -3.3 (± 0.2), respectively. Either the distinct magma batches, that coalesced to form the pluton, were much smaller in Dartmoor (compared to the Criffell and Cairnsmore plutons), or these heterogeneities may represent volumes of magma, within larger domains, that escaped homogenisation by mixing and diffusion. The existence of discrete, isotopically distinct batches of magma within the Criffell, Cairnsmore and Dartmoor plutons favours the dyke model for granitoid magma ascent through a pulsed magma delivery, in which separate magma batches (or pulses) coalesce to form plutons at or near their final emplacement levels. The scale over which such magma pulses can still be recognised varies within each pluton. The magma pulses are likely to have been larger in size, but subsequent homogenisation processes in the chambers led to a reduction in their size. However, homogenisation was not complete. In all three plutons, it is generally only the isotope ratios that display significant small-scale heterogeneity. Processes such as fractional crystallisation, are considered to be secondary, overprinting geochemical and isotopic heterogeneity from much deeper regions.