The Cambrian clastic sediments of northwest Scotland crop-out along the line of the Moine Thrust Zone between Skye in the south and Loch Eriboll in the north and form the basal 250m of a broadly transgressive Cambro-Ordovician sequence of clastic and carbonate sediments. These sediments were deposited on the passive western margin of the lapetus Ocean. The clastic stratigraphy consists of four members; the Lower Member, Pipe Rock, Fucoid Beds and Salterella Grit. The Lower Member consists of 100-125m of mature, cross-bedded quartzarenites which have been subdivided into three facies associations. The lowest association is a 10m thick series of cross-bedded channel sands interpreted as mesotidal barrier inlet deposits. This association is erosively overlain by 10m of thinly bedded, cross-bedded and parallel laminated sands interpreted as lower shoreface sediments. The remainder of the Lower Member comprises compound cross-bedded cosets 1-10m thick interpreted as tidal sandwave deposits. The sudden appearance of numerous Skolithos burrows at the Lower Member-Pipe Rock boundary is interpreted as an evolutionary event representing the colonisation of the Cambrian shelf by suspension feeding annelids. The Pipe Rock is an 85-100m thick sequence of mature, highly burrowed quartzarenites considered to have been deposited in a tidal shelf to outer shelf tempestite setting. The Fucoid Beds consists of 20m of a mixed clastic-carbonate sequence of thinly bedded wave rippled tempestites interbedded with fairweather echinoderm grainstones. The Salterella Grit is a 0-15m thick coarsening upwards sequence of muds and quartzarenites interpreted as having been deposited as tidal sandridges which went through active and moribund stages of development before being buried under carbonate platform sediments. The dominant controls on the facies developed in this sequence were thermal subsidence, eustatic sea level rise and tidal resonant effects. Two rapid shallowing events, in the middle of the Pipe Rock and at the top of the Fucoid Beds, may have been produced by variations in the spreading rate of the lapetus Ocean.

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No / The potential of Mg in Arctica islandica as a climate proxy is explored through analysis of live-collected shells from Irvine Bay, NW Scotland. Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) analysis of the right hand valve from two specimens indicates that seasonal Mg/Ca variations do not correlate with seawater temperature. The highest Mg/Ca typically occurs at the annual growth checks in ~ November¿February. Mg/Ca variations between growth checks are significant in one specimen but usually not significant in the other. Mg/Ca measurements taken laterally across the band (i.e. perpendicular to direction of the growth) to determine heterogeneity of the aragonite deposited at the same time indicates that Mg/Ca concentration decreases with increasing distance from the periostracum in both shells. X-ray Absorption Near Edge Spectroscopy (XANES) indicates that Mg is not substituted into aragonite but is hosted by a disordered phase e.g. organic components or nanoparticles of an inorganic phase. Shell Mg/Ca variations may reflect changes in the concentration or composition of the disorded phase, as well as changes in the composition of the extrapallial fluid used for calcification. Such changes could reflect the relative transportation rates of Mg and Ca to the calcification site.

This thesis investigates the potential of the bivalve Arctica islandica (Linnaeus, 1767) from fjordic sites in NW Scotland for reconstructing past marine environmental /climatic variability. Using dendrochronological and sclerochronological techniques, six master chronologies were created which when compared show little common variability between the sites, indicating no common response to regional scale forcing. The chronologies were compared to local and regional scale SST and land based datasets, with no significant, time stable responses to climate found. It is clear the growth/climate response of A. islandica from these sites is complex, potentially due to the shallow nature of the sample sites, direct local drivers such as food availability and, potentially, anthropogenic activity in the region. Geochemical analyses of the shell material were undertaken to examine the timing and magnitude of the radiocarbon bomb-peak and the stable carbon isotope signature of the oceanic Suess Effect. The timing of the radiocarbon bomb-peak in Loch Etive does not appear to match previously published results from other marine locations and are a potentially serious challenge to the assumption that A. islandica GI are always annual features. Results comparing δ¹³C values and the age of the specimen when these values are incorporated into the shell material strongly indicate an ontogenetic control over δ¹³C, meaning the Suess Effect could not be effectively investigated. To take these ontogenetic influences into account it is suggested that any data from the juvenile period of shell life is not used. Analysis of shell biometrics and morphology indicate significant relationships between shell age and height and age and weight, however the errors for these are large (±78 years and ±80 years respectively). These results indicate that despite large errors shell height, as a predictor of age, has the potential to be used for in situ population studies.