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Palaeoenvironmental studies at high altitude in eastern Africa are rare. As a result, our understanding of contemporary climate change in the region is limited. This study presents high-resolution, multi-proxy (diatoms and core geochemistry) palaeolimnological reconstructions at sites located at contrasting altitudes: Garba Guracha a cirque lake >3950 m above sea level spanning the last 16,000 years, and since the mid-Holocene at Lake Babogaya a crater lake on the western escarpment of the Main Ethiopian Rift (1800 m above sea level). These palaeo-records broadly exhibit the same glacial-interglacial dynamics and sub-millennial shifts in climate found in other palaeolimnological records from across eastern Africa. However, these shifts are more muted at Garba Guracha. Furthermore, the precise timing and expression of these climatic events is not always synchronous between the Lake Babogaya and Garba Guracha records as well as other records across eastern Africa. The Garba Guracha sediment geochemistry and diatom record is typical of a dry, post-glacial and sparsely vegetated environment with the dominance of Fragilarioid taxa and high terrigenous input. Due to the poorly developed postglacial landscape at Garba Guracha, any Younger Dryas-like drying signal would have been superimposed on to high soil erosion and a poorly productive lake environment. The retreat of a nearby ice mass may also have over-ridden any catchment development related to the start of the African Humid Period. However, in response to increased moisture availability and warming at Garba Guracha after 10,250 cal BP, catchment productivity considerably increases with a large increase in diatom productivity and organic matter content and remains high for the majority of the remaining African Humid Period interval. The termination of the African Humid Period is clear in the Garba Guracha diatom record at around 5,500 cal BP, with a second phase of change to an environment similar to the modern day after 4,500 cal BP, potentially representing the Meghalayan. Drier conditions around the Meghalayan is also documented in the Lake Babogaya record with the deposition of a Gastropod shell layer. A reduction in organic matter content following the deposition of this layer likely represents reduced productivity and a destabilising catchment under a drier climate. These drier conditions culminate in the deposition of coarse grained, terrigenous material between 3,600 and 3,300 cal BP. Following high lake nutrient content and deepening of the lake between 3,300 cal BP and 1,750 cal BP, the Lake Babogaya record suggests a relatively stable, deep lake, with only brief intervals of shallower waters, until the top of the core (~600 cal BP). The diatom record after 560 cal BP at Garba Guracha is characterised by a dominance of aerophilous taxa such as Nitzschia amphibia and Cymbelloid taxa driven by an increased growing season and nutrient loading under a drier climate. These records further reinforce the reported heterogeneous pattern of climate across the region and the significance of site-specific dynamics in the responses of catchments to regional drivers. The data produced in this study may be used to inform future climate modelling and perform more complete regional downscaling, while also furthering our understanding of palaeoenvironmental change in eastern Africa, at a variety of altitudes.

Coastal habitats are highly sensitive to change and highly diverse. Degrading environmental conditions have led to a global decline in biodiversity through loss, modification and fragmentation of habitats, triggering an increased effort to conserve these ecosystems. Remote sensing is important tool for filling in critical information gaps for monitoring habitats, yet significant barriers exist for operational use within the ecological and conservation communities. Reporting on both extent and condition of habitats are critical to fulfil policy requirements, specifically the ECs Habitat’s Directive. This study focuses on the use of Very High Resolution (VHR) optical imagery for retrieving parameters to identifyassociations that can separate habitat boundaries for extent mapping down to species level for indicators of condition, with a focus on operational use. The Earth Observation Data for Habitat Monitoring (EODHaM) system was implemented using Worldview-2 data from two periods (July and September), in situ data and local ecological knowledge for two sites in Wales, Kenfig Burrows SAC and Castlemartin SSSI. The system utilises the Food and Agricultural Organisation’s (FAO) Land Cover Classification System (LCCS) but translations between land cover and habitat schemes are not straight forward and need special consideration that are likely to be site specific. Limitations within therule-based method of the EODHaM system were identified and therefore augmented with machine learning based classification algorithms creating a hybrid method of classification generating accurate (>80% overall accuracy) baseline maps with a more automated and repeatable method. Quantitative methods of validation traditionally used within the remote sensing community do not consider spatial aspects of maps. Therefore, qualitative assessments carried out in the field were used in addition to error matrices, overall accuracy and the kappa coefficient. This required input from ecologists and site specialists, enhancing communication and understanding between the different communities. Generating baseline maps required significant amount of training data and updating baselines through change detection methods is recommended for monitoring. An automated, novel map-to-image change detection was therefore implemented. Natural and anthropogenic changes were successfully detected from Worldview-2 and Sentinel-2 data at Kenfig Burrows. An innovative component of this research was the development of methods, which were demonstrated to be transferable between both sites and increased understanding between remote sensing scientist and ecologist. Through this approach, a more operational method for monitoring site specific habitats through satellite data is proposed, with direct benefits for conservation, environment and policy.

Explosive eruptions occurred throughout the Ethiopian Rift Valley during the Quaternary, depositing tephras that have provided crucial chronology for archaeological sites in eastern Africa. However, Holocene tephras are largely unstudied and the recent volcanic history of Ethiopia remains poorly constrained. The first < 17 ka regional tephrostratigraphy is presented here, constructed using sediments from seven Ethiopian lakes: Ashenge and Hayk (Ethiopian Highlands), Dendi and Hora (Yerer-Tullu Wellel Volcano Tectonic Lineament, YTVL) and Awassa, Tilo and Chamo (central Main Ethiopian Rift, CMER). A database of 2100 major and trace element single grain glass analyses will aid the future identification of these tephras at proximal and distal locations. Peralkaline rhyolitic tephras are dominant throughout the Ethiopian Rift. Tephras are more differentiated in the central Main Ethiopian Rift than those deposited in northern Ethiopia. The uniquely phonolitic-trachytic Dendi tephras are derived from volcanoes on the rift shoulders, where magma evolved under high pressure. Archives from the Ethiopian Highlands record < 17 ka distal volcanism from seven unknown volcanic centres in the Afar Rift. Eruptions occurred every <1000 years between 15:3􀀀1:6 cal. ka BP. Different tephras were deposited in lakes Ashenge and Hayk, and they were not dispersed towards lakes further south. Tephras erupted from centres in the CMER are recorded in the Awassa, Tilo and Chamo archives. Glass compositions are indistinguishable from recent Corbetti eruptives. During < 10 ka, eruptions from Corbetti occurred every < 800 years and 6 eruptions were highly explosive. Two tephras are correlated between Tilo and Chamo (170 km SW of Tilo). However, eruptions from Corbetti are not recorded in archives from Ashenge, Hayk and Dendi. These findings demonstrate the potential for further study to construct a comprehensive tephra framework, enabling assessment of regional volcanic hazards. Further geochemical characterisation of regional volcanoes will constrain the sources of these tephras and their petrogenesis.

This thesis presents geochemical records of metalliferous enrichment of soils and isotope analysis of metal finds at Iron Age and Romano-British period settlements in North Ceredigion, Mid Wales, UK. The research sets out to explore whether North Ceredigion’s Iron Age sites had similar metal-production functions to other sites along the Atlantic fringe. Six sites were surveyed using portable x-ray fluorescence (pXRF), a previously unused method in the archaeology of Mid Wales. Also tested was the pXRF (Niton XLt700 pXRF) with regard to how environmentally driven matrix effects may alter its in situ analyses results. Portable x-ray fluorescence was further used to analyse testing a range of certified reference materials (CRM) and site samples to assess target elements (Pb, Cu, Zn and Fe) for comparative accuracy and precision against Atomic absorption spectroscopy (AAS) and Inductively coupled plasma mass spectrometry (ICP-MS) for both in situ and laboratory sampling. At Castell Grogwynion, one of the Iron Age sites surveyed recorded > 20 times Pb enrichment compared to back ground values of 110 ppm. Further geophysical surveys confirmed that high dipolar signals correlated to the pXRF Pb hotspots were similar to other known Iron Age and Roman period smelting sites, but the subsequent excavation only unearthed broken pottery and other waste midden development. Broken pottery remains were dated to no earlier than the medieval period suggesting a re-occupation, possibly for Pb prospection. It was established that Pb and metal rich soils within the villa footprint have similar isotope signatures to local ores found ca. 4km east, suggesting local ores were used in its construction, possibly with some evidence of in situ metal working.