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A 1:1,000,000 map of the Irish Sea, within the Irish Economic Exclusion Zone, is presented highlighting the spatial distribution of potential geological and geotechnical constraints to offshore wind energy development. In this mapping exercise we incorporated existing multibeam echosounder bathymetric and backscatter data collected by the Integrated Mapping for the Sustainable Development of Ireland’s Marine Resource programme. ArcGIS was used to interrogate the bathymetric data and produce maps for seabed morphological characteristics. Backscatter data and QTC Multiview derived sediment classification was used in conjunction with data from the literature to link sediment distribution with sediment transport pathways and to assess the possible impact on infrastructure. The result is a spatial constraints map, which may be used by developers, consultants and marine spatial planning authorities alike to help site projects and plan de-risking site investigations.

The Lennox Field is a saturated oilfield with a significant primary gas cap at initial conditions. Located in the East Irish Sea withincBlocks 110/14c and 110/15a, the field was discovered in 1992. First oil was achieved in February 1996. Lennox is a rollover anticline structure. The Triassic Ormskirk Sandstone Formation reservoir comprises good-quality aeolian and fluvial sandstones with typicalcporosities of 11–21%. The gas column reaches a height of c. 850 ft and overlays a 143 ft oil column. Oil initially-in-place is estimated to be 202 MMbbl, whilst total gas initially-in-place is 521 bcf. The field has been developed by a wellhead platform tied-back to the neighbouring Douglas Complex. The field development has been split into two phases: the first phase focused on oil production and involved the drilling of 12 horizontal and multilateral production wells and two gas injection wells. Oil production ceased in 2012 with total produced volumes of 103 MMbbl. The second phase comprised the gas cap blowdown, and the optimization of the existing well stock for gas production. Eni UK acquired the operatorship of the field in April 2014 and has focused on maximizing and accelerating gas production from the field.

Instructive taphonomic principles are demonstrated by the skeletons of dead invertebrates. Bivalves have resistant skeletons and are common fossils. The thin-valved razor shells, Ensis spp., have a good fossil record despite being fragile. This may be due, in part, to rapid post-mortem encrustation of valves by mineralized invertebrates. Two Recent specimens of Ensis siliqua (Linnaeus), encrusted post-mortem, are described from the Irish Sea coast of Southport, Merseyside. An articulated shell with an intact ligament is encrusted posteriorly on all surfaces by the balanid Balanus crenatus Brugiere. Barnacles inside the shell are smaller than those externally, yet may represent the same spatfall; those inside were constrained by growing in an enclosed space. To a palaeontologist, a mollusc valve encrusted inside and out by cementing organisms would be interpreted as having had a long residence time on the seafloor. This specimen demonstrates the disjunction between loss of soft tissues (days?) and loss of the ligament (weeks, perhaps months), between which encrusters may settle inside the shell, early in its post-mortem history. Similar patterns of encrustation by balanids are now known two species of Ensis and the cockle Cerastoderma edule (Linnaeus). A fragment of a single valve is encrusted only on the internal surface by serpulids and bryozoans. This is balanulith-like, but is only encrusted on the inner surface and not by balanids. Ensis valves can be reinforced by a range of calcareous encrusting organisms; an Ensis fragment encrusted both inside and out by serpulids would be worthy of being named a serpulith.

Accurate Holocene relative sea-level curves are vital for modelling future sea-level changes, particularly in regions where relative sea-level changes are dominated by isostatically induced vertical land movements. In North Wales, various glacial isostatic adjustment (GIA) models predict a mid-Holocene relative sea-level highstand between 4 and 6 ka, which is unsubstantiated by any geological sea-level data but affects the ability of geophysical models to model accurately past and future sea levels. Here, we use a newly developed foraminifera-based sea-level transfer function to produce a 3300-year-long late-Holocene relative sea-level reconstruction from a salt marsh in the Malltraeth estuary on the south Anglesey coast in North Wales. This is the longest continuous late-Holocene relative sea-level reconstruction in Northwest Europe. We combine this record with two new late-Holocene sea-level index points (SLIPs) obtained from a freshwater marsh at Rhoscolyn, Anglesey, and with previously published regional SLIPs, to produce a relative sea-level record for North Wales that spans from ca. 13,000 BP to the present. This record leaves no room for a mid-Holocene relative sea-level highstand in the region. We conclude that GIA models that include a mid-Holocene sea-level highstand for North Wales need revision before they are used in the modelling of past and future relative sea-level changes around the British Isles.

To date, Ireland’s only operational offshore wind farm project is located on Arklow Bank; a sediment bank situated nearshore in shallow (up to 2mbsl) waters. Such bank structures are preferable for wind farm development due to their competent sediment composition, shallow waters and proximity to shore for cable routing. However, as proven at Arklow Bank, issues of scour and sediment mobility around fixed foundations and cabling can compromise infrastructure stability. These issues highlight the need for adequate ground model assessments of such banks to aid planning, design, construction and maintenance phases of wind farm development.The southern Irish Sea is characterised by a series of such NNE-SSW trending sediment banks, many of which are earmarked for further wind farm developments. These coast-parallel bedforms are located approximately 10km off the south-east coast of Ireland, in circa 20-40m water depth and rise to only a couple of metres below sea level. They exert a strong control on the tidal flow pathways along the coast and offer coastal protection [1]. The banks themselves are quasi-stable in their own environment, influencing local hydro- and morphodynamics in terms of sediment waves. For offshore sediment banks to develop two fundamental conditions must be present: (1) an adequate source of sediment and; (2) a hydrodynamic regime capable of moving sediment [2]. European continental shelf sediment bank origins generally fall into two broad categories [2]; a) those formed under present day hydrodynamic and sediment conditions, or b) relict features created during post LGM transgression during periods of rapid sea level rise and stronger tidal current velocities. Paleo-tidal models have been used to reconstruct post-glacial hydrodynamic conditions in support of the proposed view of a glaciomarine environment genesis of these large bedforms in the Irish Sea [3].This study will use previously collected high resolution multi-beam echo sounder (MBES) data from the Integrated Mapping for the Sustainable Development of Ireland’s Marine Resource (INFOMAR) project in conjunction with newly obtained MBES, sub-bottom profiler, grab sample and vibro-core data to characterise; a) the stratigraphy of this highly dynamic and geologically complex region and b) sediment mobility on and around the sediment banks including their stability in the current hydrodynamic regime. Furthermore, this study will use this data to attempt to elucidate the origin of these sediment banks and their evolution through geological time. Data processed and analysed from this study will be used as an input and as validation for a coupled hydrodynamic, spectral wave and sediment transport 2D numerical model developed using MIKE 21 software. ReferencesWilliams, J.J., MacDonald, N.J., O’Connor, B.A., Pan, S., 2000. Offshore sand bank dynamics. Journal of Marine Systems, 24, 153-173. Dyer, K.R., Huntley, D.A., 1999. The origin, classification and modelling of sandbanks and ridges. Continental Shelf Research, 19, 1285–1330. Uehara., K., Scourse, J.D., Horsburgh, K.J, Lambeck, K., Purcell, A.P., 2006. Tidal evolution of the northwest European shelf seas from the Last Glacial Maximum to the present. Journal of Geophysical Research, 111(9).

The Wicklow Trough is one of several Irish Sea bathymetric deeps, yet unusually isolated from the main depression, the Western Trough. Its formation has been described as proglacial or subglacial, linked to the Irish Sea Ice Stream (ISIS) during the Last Glacial Maximum. The evolution of the Wicklow Trough and neighbouring deeps, therefore, help us to understand ISIS dynamics, when it was the main ice stream draining the former British–Irish Ice Sheet. The morphology and sub-seabed stratigraphy of the 18 km long and 2 km wide Wicklow Trough is described here from new multibeam echo sounder data, 60 km of sparker seismic profiles and five sediment cores. At a maximum water depth of 82 m, the deep consists of four over deepened sections. The heterogeneous glacial sediments in the Trough overlay bedrock, with indications of flank mass-wasting and subglacial bedforms on its floor. The evidence strongly suggests that the Wicklow Trough is a tunnel valley formed by time-transgressive erosional processes, with pressurised meltwater as the dominant agent during gradual or slow ice sheet retreat. Its location may be fault-controlled, and the northern end of the Wicklow Trough could mark a transition from rapid to slow grounded ice margin retreat, which could be tested with modelling.

Bottom cold water (BCW) is widely reported to occur in many coastal areas in summer. Some BCW masses have an increase in temperature of only 1 °C from early spring to summer (e.g., North Sea, Yellow Sea), while the others have a 4–10 °C increase (e.g., Irish Sea, Seto Inland Sea). A model of heat transport with vertical diffusion alone gave good approximation of the temperature increase in the North Sea type BCW masses, while additional heat input from other processes was required to simulate the large temperature increases in Irish Sea type BCWs. BCWs in the Yellow Sea and the Seto Inland Sea are then taken as examples to compare heat transport into the two types of BCWs through three-dimensional numerical modeling. The small warming range of the BCW in the Yellow Sea results mainly from downward heat input by vertical diffusion. In contrast, the large temperature range of warming in the BCW in the Seto Inland Sea is a result of both advection of heat from the surrounding water and vertical diffusion. We therefore infer that advection of heat into the BCW is a necessary condition for the high temperature increase range in Irish Sea type BCWs. Moreover, advection of heat into one BCW in the Seto Inland Sea intensifies from April to July, which is induced by gradually intensified bottom currents. This example supports the importance of heat transport by advection for BCWs where the temporal change in advection of heat is capable of altering the temperature increase rate inside the BCW.

Carbon Capture and Storage (CCS) is a key technology for a low-carbon energy future and will have an important role on the economic future of the UK Continental Shelf (UKCS). The East Irish Sea Basin (EISB) is a prospective area for CCS in the western UKCS. 3D seismic from the EISB were used in this study to characterise the fault network and potential fault reactivation risks associated with CO2 injection. Two main structural domains are present: a Northern domain with NW-SE faults, and a Southern domain with faults following a N-S orientation. The main storage sites consist of structural closures in Triassic strata of the Sherwood Sandstone Formation (SSF), overlain by alternations of mudstones and evaporites of the Triassic Mercia Mudstone Group (MMG). The closures occur predominantly at fault-bounded horsts, with adjacent grabens filled by thick sequences of the Triassic Mercia Mudstone Group (MMG). The fault framework was used to test, in 3D, the stress model published for the EISB and assess the fault reactivation risk associated with CO2 storage. Slip tendency values were predominantly below 0.6, suggesting the presence of stable structures in the EISB. Under the tested conditions, faults are capable of withstanding pressure increases between 3 MPa and 10 MPa before the onset of slip. The limited fault reactivation risk suggests CCS operations are suitable prospects for the EISB. This work demonstrates the additional value gained from integration of accurately constrained fault geometries in 3D stress models.

A new model of compression in the Upper Triassic overlying the Rhyl Field has been developed for the Keys Basin, Irish Sea. This paper highlights the significance of the overburden velocity model in revealing the true structure of the field. The advent of 3D seismic and pre-stack depth migration has improved the interpreter9s knowledge of complex velocity fields, such as shallow channels, salt bodies and volcanic intrusions. The huge leaps in processing power and migration algorithms have advanced the understanding of many anomalous features, but at a price: seismic imaging has always been a balance of quality against time and cost. As surveys get bigger and velocity analyses become more automated, quality control of the basic geological assumptions becomes an even more critical factor in the processing of seismic data and in the interpretation of structure. However, without knowledge of both regional and local geology, many features in the subsurface can be processed out of the seismic by relying too heavily on processing algorithms to image the structural model. Regrettably, without an integrated approach, this sometimes results in basic geological principles taking second place to technology and has contributed to hiding the structure of the Rhyl Field until recently.

A thick and relatively complete succession of Carboniferous rocks of Tournaisian to Westphalian age, together with a probable Stephanian section (Floodpage et al. 2001) was deposited throughout the two main areas in the Irish Sea region. The larger Central Province Trough in the south includes the East Irish Sea Basin (EISB)-Quadrant 109 Syncline-Kish Bank Basin, linking the onshore successions of the Craven Basin (Chapter 11) and Dublin Basin (Chapter 21). The smaller Peel Basin-Solway Basin (Figure 16.1) represents the extension of the onshore Solway Basin (Chapter 13) and continues westwards between the Drogheda Shelf and the Balbriggan Block (Chadwick et al. 2001; Sevastopulo & Wyse Jackson 2001). Seismic data suggest that there is probably some 4000 m to 5000 m thickness of Carboniferous strata in the Solway Basin and EISB (Chadwick et al. 2001). The present day distribution of Carboniferous strata is controlled by the effects of uplift and erosion associated with Variscan basin inversion (Chadwick et al. 2001). Separating the Solway Basin and EISB is the Manx-Lakeland Ridge, which is believed to extend westward to form the Balbriggan Block (Chapter 18).

Pore systems of tight-gas reservoirs control important parameters such as flow capacity, producible pore volumes, hydrocarbon flow rates and storage which are complex to characterise and to quantify. Detailed understanding of 3D pore structure is vital in predicting tight-gas reservoir productivity. This study investigates the pore architecture of a sandstone sample from Collyhurst Sandstone Formation, northern England, a tight gas reservoir. X-ray Computed Tomography (XCT) was employed to quantify the pore system (pore size, shape, geometry, and connectivity). Three types of pores were identified: inter-grain pores which are at the boundary of detrital grains and/or authigenic minerals, intra-grains pores which are pores within the detrital mineral grains, and intra-cement pores which are pores within the cement phase (authigenic minerals). The first pore type is primary in origin, whereas the latter two are secondary pores. A centerline tree and a pore network model (PNM) algorithm were applied for pore network analysis and a porosity value was estimated. The image-based porosity value was validated with laboratory experimental measurement. 3D image estimates 3.1% volume porosity, while 4.6% was recorded from the laboratory experiment. Spatial quantification of pore types and analysis of pore connectivity of the studied sandstone improves understanding on gas flow behaviour and gas storage. Furthermore, the results are useful in predicting permeability and multi-flow phase properties in a tight gas reservoir.

Examples of epigenetic hematite mineralization located at the margins of the East Irish Sea Basin have been sampled for palaeomagnetic investigation to establish the timing of ore formation. Samples collected from 10 sites in Cumbria are dominated by hematite of near-pure composition and characterized by dual polarity and, in part, dual component magnetizations that yield palaeopoles (nine sites) between 50°N, 130°E and 50°N, 150°E. In contrast, samples recovered from seven sites on the Isle of Man have more varied mineralogical compositions that include ferromagnets with lower unblocking temperatures. Manx hematite mineralization also exhibits dual polarity, but magnetizations yield steeper inclinations with palaeopoles lying between 55°N, 130°E and 70°N, 150°E. Steeper directions probably reflect minor tilting of the Manx block following hematite emplacement. Correlation of poles with the European apparent polar wander path indicates that these ore deposits formed during the Middle Triassic. Results show that hematite mineralization sited at the margins of the East Irish Sea Basin is essentially contemporaneous and establishes, for the first time, an underlying temporal relationship between these geographically dispersed ore bodies. Dating places the mineralization within a broader extensional geotectonic regime associated with the early rifting of Pangaea in the North Atlantic. The context implies a causal link between crustal extension, development of ore-forming fluids within the evolving East Irish Sea Basin, and subsequent migration of fluids to basin margins where iron was precipitated as hematite. Supplementary materials: Locations and details of palaeomagnetic sample sites and a tabulation of selected reference palaeomagnetic poles defining the Triassic and Early Jurassic segment of the apparent polar wander path for the European sector of the Eurasian plate are available at www.geolsoc.org.uk/SUP18691.

Results from an eddy-admitting and a non-eddy admitting ocean circulation model with parameterizations for barotropic tide-induced bottom friction mixing are compared to two observation data sets. The use of tide-induced vertical viscosity and diffusivity in addition to other large-scale drivers of ocean mixing processes such as wind and current shear leads to moderate improvements and more realistic upper-ocean temperature structures on larger scales. However, parameterized tide-induced mixing in the eddy-admitting model causes too strong mixing in shelf sea areas such as the British Channel/Irish Sea and the East China/Yellow Seas. The overall result from both models is that care must be taken when tidal mixing parameterizations are applied to ocean circulation models. Each individual use of a tidal mixing parameterization requires careful fine-tuning; and its impact on model skill should be considered together with other relevant parameterizations. We discuss possible reasons for the excessive vertical mixing and propose options which should lead to improved simulations with barotropic tidal mixing parameterizations.

The resonances of the English Channel and Irish Sea are investigated using the methods of Webb (2012a) together with an Arakawa C-grid model of the region under study. In the semi-diurnal tidal band, the high tides of the Bristol Channel and Gulf of St. Malo are shown to be due to two shelf resonances which strongly couple the two regions. In the diurnal band, the response is complicated by the presence of continental shelf waves.

Between 2004 and 2011 Graham Hill and Dave Edwards plotted nearly eight thousand prehistoric artefacts from ploughed fields across the Clodgy Moor area of West Penwith. In 2011 a project was carried out by the Historic Environment Service Projects team, Cornwall Council, the Portable Antiquities Scheme and the Cornwall Archaeological Society to catalogue and digitize all the finds recorded from the fieldwalking.The project demonstrated that some places within the project area were persistent locales which were occupied throughout the Mesolithic and Neolithic periods. The results were particularly significant because they shed light on the context of the production of greenstone axes, widely exchanged around Britain and across the Irish Sea during the Neolithic, and suggest why, despite large numbers of artefacts, no greenstone ‘axe factory’ site has been found close to the potential sources of the greenstone before.

Journal article An assessment of the complex evolution of climate change signals in the Irish Sea over the 21st century is presented in this paper. Potential impacts of climate change on the local hydrography are explored and interrelationships between fundamental oceanographic shelf sea phenomena investigated. A regional ECOMSED ocean model is used to downscale a 120-year period (1980-2099) of the SRES A1B scenario experiment from a global ocean model. A detailed regional analysis shows that local climate changes may be significantly different from the expected global changes.This research suggests that in the future the Irish Sea will be warmer with sea surface temperature increase of around 1.9 degrees C. Maxima and minima annual temperatures will occur around 2 weeks later each year relative to the present climate. Geographically, shallow waters along the coastline and in the eastern Irish Sea will exhibit strongest warming due to increased heat uptake during summer and autumn and reduced heat loss in spring and winter. Warming in the deep channel in the western Irish Sea will be generally weaker with seasonal variability subdued due to a large heat storage capacity. The warming will be largely stored in the surface layer of the water column leading to strengthening of stratification and a considerable decrease in the thickness of the mixed layer. The western Irish Sea gyre will become stronger and result in substantial reinforcement ( > 30%) of southward currents along the east coast of Ireland. Net northward flow in future predicted climate conditions will be maintained at the current annual rate. Steric sea level is projected to rise by 0.31 m during the 21st century, leading to an overall projected sea level rise of approximately of 0.47 m.Future changes to oceanographic parameters, flushing times and hydrodynamics of the Irish Sea are likely to alter the habitat and distribution of marine species; the finding of this research are therefore of great interest to ecologists and the fishery industry. (C) 2012 Elsevier Ltd. All rights reserved. Environmental Protection Agency, Ireland; Higher Education Authority/Programme for Research in Third-Level Institutions, Cycle 4 (HEA/PRTLI4) peer-reviewed

The observation and prediction of the mobility of the seabed are in high demand with rapidly expanding offshore engineering developments and the increasing urgency to start mitigation against changing coastlines. From repeatedly surveyed sediment wave fields in the Irish Sea, average sediment wave migrations have been mapped, from which broad-scale net sediment transport directions can be derived. The proximity of bathymetric highs and lows seems to redirect sediment migration pathways and increases migration rates by a factor 5 on average via current deflection and amplification. A few hundred sediment waves were analysed geometrically in this study and compared to their migration behaviour, revealing a lack of statistical correlation. Sediment wave lee slope directions, asymmetry indices and other geometrical parameters appear poorly indicative of their degree of mobility in the Irish Sea. A considerable amount of sediment waves counter-intuitively migrate in the direction of their gentle stoss slope, i.e. opposite to the expected sense of migration. Even when considering the limitations of the predominantly 2-dimensional sampling method, these results fundamentally challenge established assumptions on the indicative meaning of sediment wave geometry. They question the validity and robustness of sediment wave migratory predictions based on single geometrical readings that fail to represent the complexity of local hydrodynamics and partial sediment wave modifications. Until predictive tools for sediment wave migration are developed that can pass the test in all aquatic environments, repeat surveying with sonar systems provides the only reliable way to record true natural variability.

Journal article The western Irish Sea gyre (WISG) is a cyclonic baroclinic flow around a dome of stagnant water which develops each year during the heating season in the western Irish Sea. Research was carried out to determine long-term changes in the strength of stratification within WISG and associated changes in the gyre structure, circulation patterns and retentive properties. Model simulations were carried out for the 58-year period 1951-2008. The characteristics of the gyre were quantified by means of potential energy anomaly (PEA), measuring the strength of stratification, and total kinetic energy (ME), reflecting the strength of cyclonic circulation. Additionally, long-term changes in flushing rates within the gyre were assessed.Results show that stratification in the western Irish Sea consistently begins to develop in March, increases linearly from April till June, peaks at the beginning of July and remains at close to maximum level throughout the month of July, before a start of a sharp decline at the beginning of August. The strength of stratification is significantly correlated with averaged summer air temperatures and summer wind speeds. Trend analysis of PEA shows an increase in the stratification strength over the period considered; the increase of PEA peak value is accompanied by a shortening of the gyre duration and a delay in the timing of the peak value. There is also an increasing trend in the KE value, showing that the thermal stratification plays a crucial role in the hydrography of the region. Flushing analysis shows that the stronger the stratification the lower the residence time and thus the faster the removal of the material from the western Irish Sea. Residence time within WISG shortens on average by 8 days over the 58-year period. (C) 2011 Elsevier Ltd. All rights reserved. Environmental Protection Agency (Ireland) peer-reviewed

A long-range atmosphere transfer of radionuclides from nuclear explosions and nuclear plant accidents is considered. Data on radionuclide transport in the Yenisey, Pripet, Sozh, Iput’, and Besed’ rivers are presented. The time of the radionuclide transport from the Irish Sea to the Baltic and Barents seas is defined using changes in the cesium 134/cesium 137 isotope ratio.

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 166497, ’Mapping CO2 in Real Time in Hydrocarbon Reservoirs With Downhole Fluid Analysis: First Successful Experience in the East Irish Sea, UK Continental Shelf,’ by B. Quayle, S. James, and M. Quine, Centrica Energy, and I. De Santo, P. Jeffreys, and J.Y. Zuo, Schlumberger, prepared for the 2013 SPE Annual Technical Conference and Exhibition, New Orleans, 30 September-2 October. The paper has not been peer reviewed. This paper describes the first successful attempt on the continental shelf offshore UK to map carbon dioxide (CO2) in real time while logging during a drilling campaign in the East Irish Sea. Reservoirs in this sea’s basin contain varying proportions of CO2, nitrogen (N2), and hydrogen sulfide (H2S), in addition to oil and methane. Two of these wells develop the Rhyl gas field. Downhole-fluid-analysis (DFA) technologies were deployed with a wireline-formation-testing (WFT) tool to measure CO2 content accurately downhole. Introduction The Rhyl field was discovered in 2009 and received development approval in 2012. It is located 11 km north of the North Morecambe field. The North and South Morecambe fields were discovered in the 1970s, with some 7 Tcf of gas initially in place. Production from the Rhyl field extends the longevity of these assets. Vertical and horizontal variations in CO2 content in the Rhyl field were assessed across the Triassic Ormskirk sandstone, the upper member of the Sherwood sandstone group. The Ormskirk sandstone formation represents the principal reservoir target in the East Irish Sea, comprising high-porosity aeolian and fluvial sandstones with variable grain size and playa mudstones. Gas Composition in the Rhyl Field The composition of the gas found in Rhyl includes both hydrocarbon and nonhydrocarbon components such as N2 and CO2. The N2 is derived from late-stage hydrocarbon generation, while isotope data indicate that the CO2 has a magmatic origin. It is believed to have been exsolved from the magma of a series of Tertiary dolerite intrusions into the Ormskirk sandstones in close proximity to the Rhyl field. The samples collected during the drillstem test conducted on exploration Well 113/27b-6 provided several qualitative indications of a higher CO2 content than was originally expected from the correlation with the nearby North Morecambe field: a high gas density measured at the separator and difficulty in sustaining a flare.

Data from time-lapse single-beam and multi-beam bathymetric surveys are used to assess the rate and scale of morphological change at shipwreck sites caused by anthropogenic forcing. The technique is illustrated by characterizing changes in wreck site morphology over two sites located on the east coast of Ireland – the Drogheda Boat site on the River Boyne and the Arklow Bank site in the Irish Sea. Results indicate that repeated bathymetric surveys accurately and rapidly capture morphological change, with time-lapse accretion–erosion models indicating possible erosion rates of up to 0.04 m per day and accretion rates of 0.36 m per day at dynamic riverine and marine sites in response to external triggers. These data are valuable in understanding site formation processes at fully submerged archaeological sites and in the derivation of high-resolution site formation models.

The Lg wave quality factor (QLg) in Britain has been modelled using data from the UK Seismic Network, operated by the British Geological Survey. The data set consists of 631 vertical, mostly short-period recordings of Lg waves from 64 earthquakes (2.7–4.7 ML) and 93 stations. We have inverted for both regional average QLg and tomographic images of QLg , and simultaneously a source term for each event and a site term for each station for 22 frequencies in the band 0.9–10.0 Hz. The regional average model is 266f0.53 between 1.0 and 10.0 Hz and indicates that attenuation in Britain is slightly higher than in France, and significantly higher than in eastern North America and Scandinavia. Tomographic inversions at each frequency indicate that QLg varies spatially. Broadly speaking, southeastern England, the Lake District and parts of the East Irish Sea Basin, and a small region between the Highland Boundary Fault and the Southern Uplands Fault are characterized by higher than average attenuation. Southwestern England, eastern central England and northwestern Scotland are regions of relatively low attenuation. To some extent, these regions correlate with what is known about the tectonics and structure of the crust in the UK.

This study uses a series of scenarios of wave (boundary) and wind (local) forcing to examine the sensitivity and to quantify the effects associated with nesting ProWAM and POLCOMS models for downscaling predictions of waves in the Irish Sea. The model results show that the response of the modelling system to the wave and wind forcing during the downscaling varies widely depending on wind conditions. Generally, the wave forcing has a greater effect on overall wave prediction in most of the Irish Sea, except for the eastern Irish Sea/Liverpool Bay. The study also suggests detailed look-up tables at specific locations to quantify the impacts of the different forcing scenarios over the Irish Sea, which can be readily extended to the location on any other sites.

Beach profile data, collected twice per year at 19 stations over a 25 km length of coastline in Tremadoc Bay, have been analysed to quantify the inter-annual variability in beach levels over a 7 year period and the results compared against the output of a numerical model. Using hourly wind data as forcing, the morphological development of northern Tremadoc Bay was simulated by wave, tidal, longshore transport, total transport and bed level change models. The modelling methodology was efficient and innovative, allowing realistic simulations of long duration with a time step of 1 h, hence capturing the high frequency nature of wind events. The model was run for each of the 7 autumn/winter periods (generally November–April) and the modelled net change in beach levels compared with the data from all 19 stations. The model results had reasonable agreement with the beach profile surveys. However, the observed magnitude of bed level change in the bay lagged the model output by 1 year, indicating that sediment processes acting over a larger area are important in a relatively localised study of inter-annual variability.

This study is part of a basin-wide re-evaluation of Irish Sea glacigenic deposits which aims to test whether diamicts, collectively known as Irish Sea Tills, represent in situ glacimarine sediments or sediments that have been reworked or deformed by the Last Glacial Maximum Irish Sea Glacier. New results are presented for two key localities at Abermawr and Traeth y Mwnt in Wales. Unlike previous studies in the Irish Sea region that have focused on macro-scale sedimentology and structural analyses, this study combines macro-scale and micro-scale sedimentary analyses. This approach reveals that the dominant diamict facies at Abermawr are subglacially deformed primary (glaci)marine deposits, emplaced by the Irish Sea Glacier. An inland glacial source is unlikely. The Traeth y Mwnt diamicts are likely to be subaqueous in origin, possibly formed in an ice-dammed lake in the Mwnt embayment. There are no indications of subglacial deformation or shearing at Mwnt; deformation structures are related to gravity-driven or density-driven mechanisms.

A two-dimensional model has been developed in order to improve understanding of the processes which interact to maintain the sediment concentrations at an isolated turbidity maximum in the Irish Sea throughout the year. The model comprises two interchangeable populations of particles with different diameters, one of fine cohesive material, the other made up of flocs. Both populations are slow settling, and subject to horizontal diffusion, resuspension, settling, aggregation and disaggregation. The equations used to describe the processes of aggregation and the break-up of flocs in response to sediment concentration and turbulent shear have been developed by the tuning of the model to observations. Due to high turbulent shear at the turbidity maximum, the particles are predominantly fine, while the sediment in the surrounding water is made up of larger flocs. Diffusion of small particles out of the turbidity maximum balanced by the diffusion of aggregated material towards it provides a mechanism for its maintenance. The modelled sediment concentrations at the turbidity maximum can be reproduced year-on-year, with no loss due to diffusive processes. This is achievable with a limited, exhaustible source of material which is not replenished once resuspended. Through comparison with satellite imagery the correlation of the modelled sediment concentrations with observations is investigated, both spatially and temporally. The seasonal cycle is reproduced well by the model with winter and summer concentrations matching those observed. Spatially the model also performs well in both turbid regions and those where the surface sediment load is low.

Simon P. Holford, Paul F. Green, Jonathan P. Turner, Gareth A. Williams, Richard R. Hillis, David R. Tappin & Ian R. Duddy

Understanding the contribution of high-energy events (e.g. storms, tsunami) to coastal evolution is currently much debated. Field investigations in North Wales on Anglesey and the Lleyn Peninsula have identified four sites where imbricated boulder trains occur that are discriminators of wave characteristics. Clast analysis indicates that storm wave heights (c. 20 m), in excess of known extremes (5

The superficial deposits at Morfa-bychan have previously been interpreted as deposited by Welsh ice. A reconsideration, including: stone orientation analysis, suggests however that they consist of screes and solifluction deposits with subordinate rain-wash gravels, and a thin loess—the whole laid down under periglacial conditions, when the Irish Sea ice no longer reached the area. There is no direct evidence for dating but their volume and field relations suggest they represent the deposits of the last glaciation.

An analysis of the preferred orientation of the long axes of erratics contained within the superficial deposits of the Lleyn Peninsula indicates that during the two recorded glacial advances the area was invaded by ice from two source regions—the Irish Sea ice-sheet and local Welsh ice-bodies. An attempt is made to re-construct the pattern of ice movement during both glacial advances, to determine the extent to which ice from each source region penetrated Lleyn, and to interpret the environment under which the tills were deposited.

Glacigenic sediments exposed at Rhosesmor, Clwyd, North Wales, were deposited in a small proglacial lake ponded by the stagnating margin of the Late Devensian Irish Sea icesheet. Three major fades assemblages are identified and show a prograding sequence of topset, foreset, and bottomset deposits associated with two Gilbert-style deltas stacked one above the other. The lower delta is associated with a lake level at c. 180 m OD. A subsequent ice-marginal readvance raised the lake to c. 192 m OD, drowned the lower delta and caused the growth of a second delta by an iceward shift of facies. It is estimated that the life of the lake was of the order of 90 years during which average sediment in-fill amounted to some 4±104 m3 per annum.

Data are presented here on the anthropogenic 129I inventory in regions that have been strongly affected by releases from European reprocessing facilities which, to the authors’ knowledge, presently account for >90% of the global isotope source in the Earth’s surface environment. The results show that >90% of the isotope inventory occurs in marine waters with the Nordic Seas and Eurasian basin of the Arctic Ocean containing most of the 129I. Within the terrestrial environment of Europe, soils contain the largest part of the isotope inventory. However, the inventory of the terrestrial system did not provide clues on the most plausible atmospheric source of 129I to Europe, thus supply from both gaseous and marine releases is proposed. The sum of the total inventory in both the marine and terrestrial environments did not match the estimated releases. This imbalance is likely to relate to unconstrained inventory estimates for marine basins (Irish Sea, English Channel and North Sea) close to the facilities, but also to the occurrence of 129I in the biosphere, and possible overestimated releases from the nuclear reprocessing facilities. There is no doubt that the available data on 129I distribution in the environment are far from representative and further research is urgently needed to construct a comprehensive picture.

Accelerator mass spectrometry 14 C ages on monospecific marine microfauna from raised mud record initial deglaciation of the eastern coast of Scotland before 21.0 cal ka bp. Two subsequent ice-margin readvances occurred prior to the Loch Lomond Advance and are identified from ice-contact deposits overlying marine mud. The Lunan Bay Readvance dates to 20.2 cal ka bp, and possibly 18.2 cal ka bp. The younger Perth Readvance occurred between c . 17.5 cal ka bp and 14.5 10 Be ka. Within dating uncertainties, these readvances are similar in age to ice-margin fluctuations documented from the Irish Sea Basin and northwestern Ireland and record three near-synchronous fluctuations of much of the British–Irish Ice Sheet margin during the last deglaciation, suggesting a common response to regional climate forcing.

A finite element model of the west coast of Britain is used to determine the spatial distribution of the M2, S2, N2, K1, O1, M4 and M6 tides in the region. A sensitivity study of the influence of bottom friction upon the M2 tide and its higher harmonics, shows that increasing friction coefficient in an M2 tide only calculation, from 0.0025 to 0.0030 has a larger effect than the addition of the other major constituents. Although the M2 tidal amplitude over the west coast of Britain is sensitive to frictional effects, the co-phase distribution is not significantly influenced by friction. Detailed comparisons of the computed tide in the eastern Irish Sea with observations and an earlier high-resolution finite difference model of the region, shows an improvement in accuracy of the tidal solution derived with the finite element model. The ability of the finite element model to refine the mesh in the near coastal region contributes to this improvement in accuracy. A study of the spatial change of the computed tide in nearshore regions shows significant variability on scales of the order of 0.5 km. This suggests that detailed topography and associated mesh sizes in near coastal regions need to be below this space scale.

A simple and efficient method to improve morphological predictions using depth-averaged tidal models is presented. The method includes the contribution of secondary flows in sediment transport using the computed flow field from a depth-averaged model. The method has been validated for a case study using the 3D POLCOMS model and ADCP data. The enhanced depth-averaged tidal model along with the SWAN wave model are applied to morphological prediction around the Lleyn Peninsula and Bardsey Island as a case study in the Irish Sea. Due to the presence of a headland in this area two asymmetrical tidal eddies are developed in which the cyclonic eddy is stronger as a result of Coriolis effects. The results show that the enhanced model can effectively predict formation of sand banks at the centre of cyclonic eddies, while the depth-averaged model, due to its inability to accommodate secondary flow, is inadequate in this respect.

Six cores, geophysical data (multibeam bathymetry), surface grab samples and video photography were collected from the area of the Western Irish Sea Mud Belt (WISMB). These data were analysed to determine the radionuclide input from the Sellafield nuclear facility on the eastern (UK) seaboard of the Irish Sea, and subsequently to assess the influence of bottom trawling and bioturbation on the surface and near-surface sediments. Results show significant changes in the sedimentation and geochemical regime in the WISMB due to anthropogenic causes (bottom trawling and radionuclides derived from the power plant). These changes are consistent with the concept of the Anthropocene time period. Levels of anthropogenic radionuclides measured in two of the cores enabled construction of a chronology correlated with recorded values of discharge from the Sellafield facility. Excess 210Pb and the anthropogenic radionuclide 137Cs proved useful as stratigraphic marker tools. These radionuclide data also enabled quantification of the effects of trawling, which was visible on acoustic seabed maps. Bottom trawling has removed an estimated 20 - 50 cm of the upper seabed.

The Upper Cretaceous sub-Period saw the deposition of the Chalk over much of the British Isles region, with progressively inundated land areas. By the Late Maastrichtian land areas were at their minimum and a thick Chalk sequence accumulated over the region. In the Early Palaeocene uplift in the Irish Sea interrupted deposition, but in many areas marly chalk deposition resumed. Mid-Palaeocene uplift led to dramatic erosion of this cover so that in most places all the Danian, Maastrichtian and, in some places, Campanian and even Santonian Chalk were removed before deposition of Late Palaeocene sediments; this widespread and pervasive erosional event has masked the true extent of Maastrichtian deposition. In areas outside the Palaeocene basins erosion of the Chalk continued, rapidly exposing underlying rocks.

Caudal thorns from bathyrajids, for which surface band patterns have previously been correlated with an annual cycle of vertebral band deposition, were examined to ascertain the underlying growth band structure with a view to understanding their growth processes. Caudal thorn samples from Bathyraja brachyurops, a commercial ray species from the Falkland Islands were sectioned transversely using both resin embedding and decalcification/wax embedding procedures. Sectioning revealed that internal bands formed as a series of cones underlying each other, and that broad surface broad bands formed annually during periods of rapid somatic growth. Surface ridges representing a near stasis in somatic growth formed at the periphery of each cone. This proposed growth process was further verified by the incorporation of tetracycline at the periphery of caudal thorns from a tag-recaptured bathyrajid. The benefits of using sectioning to enhance band resolution of larger specimens of slower growing species, particularly in the case of worn and tightly spaced surface band patterns are also discussed. Introduction In the majority of ray species caudal thorns are found securely embedded in the caudal tissue overlying the spinal column. It is probable that they have a defensive function, and may also assist in the emergence from the egg case. The surface bands of caudal thorns from bathyrajids have previously been correlated with an annual cycle of vertebral band deposition (Gallagher and Nolan, 1999). For a structure to be used as a valid ageing tool it is important to have an understanding of its growth and band formation processes (Cailliet, et al., 1983; Casselman, 1987). To date, however it is unclear how growth bands form in caudal thorns, and how the surface sculpture relates to the underlying morphology. Furthermore bathyrajids are typically slow growing species (Gallagher and Nolan, 1999) and therefore difficulties have been encountered in resolving both worn bands near the thorn tip and tightly spaced bands towards the periphery (Gallagher, 2000). Sectioning of growth structures has previously been recommended for both vertebral centra and dorsal fin spines to help improve band resolution, particularly in slow growing elasmobranchs (Cailliet, 1990; Branstetter and Musick, 1994). This study investigates the structure and growth processes of caudal thorns from Bathyraja brachyurops, a commercially important bathyrajid from the Falkland Islands, which an ageing study using whole caudal thorns has been carried out previously (Gallagher and Nolan, 1999). * Current address; Irish Sea Fisheries Board (BIM), Crofton Road, Dun Laoghaire, Co. Dublin, Ireland.

Accurate predictions of wind waves with different lead times are necessary for a large scope of coastal and open ocean activities. Attempts to improve wave short-term forecasts based on artificial neural networks are reported. Hourly observations of significant wave heights and zero-up-crossing wave periods from two sites offshore the Atlantic and the Irish Sea coasts of Ireland are used to train and validate these networks. Two different approaches are involved. One of them corrects the predictions solely using the initial simulations of the wave parameters with leading times from 1 to 24 h. Another one allows merging the measurements and initial forecasts. The proposed procedures provide satisfactory results at both locations.

The temperature structure of the Irish Sea is investigated using a 3-yr simulation with a high-resolution (∼1.8 km) three-dimensional baroclinic model (the Proudman Oceanographic Laboratory Coastal-Ocean Modelling System) and CTD and Advanced Very High Resolution Radiometer observations. This paper focuses on the extent to which (horizontal) advection determines the temperature structure. It is found that it has a significant effect on the depth-mean temperatures throughout the region and on the vertical profiles in seasonally stratified areas, such as the Celtic Sea and western Irish Sea. There is depth-mean advective heating during the summer in these stratified regions, whereas in well-mixed regions advection tends to reduce the amplitude of the seasonal cycle. Through an analysis of the terms in the temperature equation, the warming of the “cool pool” waters of the western Irish Sea can be attributed to the advection of partially well-mixed waters into the stratified region from the north. Th...

Suspended particulate matter (SPM) plays an important role in the transport of metals and other contaminants in the marine environment. To varying degrees dissolved metals are scavenged by suspended particles and this can have a significant impact on the transport and dispersion of the metal. In contaminated areas, such as the Irish Sea, the SPM becomes increasingly important in understanding the transport and fate of contaminants. Despite its importance, measurements of SPM in the Irish Sea are sparse. This paper presents measured SPM concentrations from a long-term sampling campaign from 25 sites in an area of the Irish Sea between Anglesey and the Isle of Man which were sampled over 14 months (July 1998–August 1999) at 5 and 30 m depth. In total 585 measurements were made. A transmissometer was also deployed on some occasions to look at the depth dependence of SPM. Results showed an average SPM concentration of 2.14 mg l −1 with a maximum value of 6.28 mg l −1 and a minimum of 0.30 mg l −1 . The strongest relationship found was between the SPM and the spring-neap tidal cycle, which outweighed any seasonal variation. Spatially, the SPM was highest in the south and east of the region sampled and is probably due to higher tidal velocities and greater availability of fine sediment in these areas. There was no evidence of SPM varying with depth in the water column.

The Hamilton and Hamilton North Fields are located in Block 110/13a in the East Irish Sea, and contain 627 BCF and 230 BCF GIIP, respectively. First gas was produced from the Hamilton North Field in December 1995. The fields are being developed with four producers in the Hamilton Field and three in the Hamilton North Field. The Hamilton Field structure consists of a N-S trending horst block with dip closure to the north and south, while the Hamilton North structure is defined by major faults to the north and west with dip closure to the east and south. The gas is trapped in the highly productive Triassic Ormskirk Sandstone Formation. The reservoir comprises high porosity aeolian and fluvial sandstones. Depth to reservoir is shallow (2300-2600 ft) with the gas-water contact being at 2910 ft in the Hamilton Field and 3166 ft in the Hamilton North Field. Reservoir quality is principally controlled by primary depositional processes and no significant diagenetic effects are observed. The hydrocarbon filling history was complex, with at least two phases of hydrocarbon generation. Hamilton North gas is sweet whereas the Hamilton gas contains up to 11OOppm H 2 S, which is removed during processing at the Douglas complex and at the Point of Ayr gas terminal. Cumulative gas production to May 1999 was 180 BCF and no water-cut has been observed to date.

Although the problem of predicting storm surge elevations has received significant attention, the simulation of currents has suffered because of lack of current observations during surges. Current measurements made during surge conditions are presented here and are used in combination with three-dimensional models to understand processes producing storm currents in the Irish Sea. A coarse-grid (resolution of order 7 km) model of the west coast of Britain together with a fine-grid (of order 1 km) model of the eastern Irish Sea is used to examine the processes, namely, open boundary forcing of the west coast model and wind fields, that produced flows within the eastern Irish Sea during the storm surge of November 1977. Simulations of the surge show that the fine-grid model nested within the west coast model can reproduce observed coastal changes in surge elevation. However, an observed major inflow that was recorded by current meters in the region, prior to a storm surge elevation peak, is not repr...