Helene Burningham

Formation of bedrock-cut ventifacts and late Holocene coastal zone evolution, County Donegal, Ireland

Wind‐etched rocks (ventifacts) at Gweebarra Bay, County Donegal, northwestern Ireland, are located <+2 m above mean high‐water springs (MHWS) on a glacially eroded bedrock shore platform (<10 m wide, 200 m long at MHWS). Prevailing southwesterly winds transport sand across the platform from the adjacent beach. Ventifacts, found on the windward‐most 20 m of the platform, decrease in frequency and degree of wind alteration with distance. Near the beach, ventifacts have two to three wind‐etched faces (facets), both linear and serrated keels, and are pitted, grooved, and polished. Farther from the beach, ventifacts are less frequent; have fewer facets, pits, and grooves; and show curved keels. Facets nearest the beach lie perpendicular to prevailing winds but are wind parallel farther away. This reflects structural control on the shape and orientation of bedrock blocks protruding into the wind stream. Nine possible ventifact morphologies are identified on the basis of wind‐approach angle and dip angle of the windward face. Three morphological types dominate at Cashelgolan (moderately inclined, perpendicular facets; moderately inclined, oblique facets; steep, oblique facets). Calculated sand transport is likely only for limited (25%–28%) periods of time under the contemporary wind regime. This suggests ventifacts are not developing actively at this time but may reflect long‐term (more than hundreds of years) wind activity and/or stronger winds. Historical evidence for high‐magnitude winds and storms suggests ventifacts formed within the last 2000 yr, possibly during the Little Ice Age (LIA). Regional evidence also shows that coastal regimes intensified during the LIA, with increased onshore winds, waves, sediment fluxes, and periods of sand dune building.

Coasts and climate: Insights from geomorphology

Geomorphology is increasingly engaged with the connections between coastal behaviour and climate variability and change. While impacts of climate change at the coast are often primarily viewed in terms of landform adjustments to accelerated sea-level rise, geomorphologists are also starting to unlock the subtleties of how coastal processes are forced by a broader suite of climate factors. This progress report highlights three main strands of recent geomorphological research in this vein: the search for a broader suite of climatic signatures in recent coastal deposits; empirical analyses of the linkages between climate variables and contemporary shoreline change; and enhancement of our capability to predictively model climate-driven changes in coastal morphology.

Large-scale spatial variability in the contemporary coastal sand and gravel resource, Suffolk, eastern UK

The response of coastal systems to changes in sea level and storm events is often dependent on the availability of sediment and sustainability of sediment supply. This paper analyses the changing sediment resource of a driftaligned shoreline in eastern England, UK, over centennial and decadal timescales. Spatial variability in cross-shore extent and elevational distribution of this mixed sand and gravel system exerts a significant control on the ability of different stretches of this shoreline to respond dynamically to changes in marine forcing. Furthermore, anthropogenic interference has led to the development of unnaturally high beach ridges in some places, which contrasts with the absence of intertidal or supratidal sediment along stretches dominated by seawalls.

A paraglacial coastal gravel structure: Connell's Bank, NW Ireland

ABSTRACT Knight, J., Burningham, H., 2014. A paraglacial coastal gravel structure: Connells Bank, NW Ireland. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 121–126, ISSN 0749-0208. Coastal gravel structures have been well documented worldwide and are formed dominantly by onshore wave transport of gravel, mainly during storm events. They are commonly observed along paraglacial coastlines where their origins are more ambiguous because of the effects of antecedent patterns of sediment supply, glacioisostatic sea-level change, and contemporary coastal processes. This paper describes the properties and polygenic origin of Connells Bank, a small paraglacial gravel structure on the Atlantic-facing coast of NW Ireland. This feature has been shown on historical maps, air photos and satellite imagery since ca. 1850 but its outline has varied depending on seasonal migration, expansion and contraction of a sand veneer. It has also acted as a major control on tidal channel position within the estuary, and thus on sensitivity of the estuary system to ocean forcing. In detail, the bank surface is composed of cobbles sourced from outside of the immediate catchment. These surface cobbles are strongly winnowed, forming a lag deposit, whereas below the surface, cobbles exist within a granule and shell matrix. A significant proportion of surface cobbles show evidence for recent ventifaction by blown sand at low tide. The paraglacial evolution of Connells Bank since the last glaciation comprises the following stages: (1) deposition of coarse glacigenic sediment as a moraine or proximal outwash fan during the late Pleistocene lowstand; (2) reworking of sediments onshore during early Holocene sea-level rise; (3) surface winnowing during mid to late Holocene tides and storms; and (4) surface cobble modification by contemporary wind abrasion.

Travelling forelands: complexities in drift and migration patterns

ABSTRACT Burningham, H., French, J.R., 2014. Travelling forelands: complexities in drift and migration patterns. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 102–108, ISSN 0749-0208. Cuspate forelands have been described from a range of shorelines around the world, but in the majority of cases, the foreland maintains a constant position relative to the neighbouring shoreline. Here, we describe the contemporary geomorphology and historical evolution of a small cuspate foreland on the Suffolk coast, UK, which has been migrating northward for several centuries. Benacre Ness, a mixed sand and gravel sedimentary accumulation, is currently located at Kessingland, 5 km to the north of Benacre, from which it gained its name when adjacent to it in the 19th century. The foreland was previously called Covehithe Ness, having been adjacent to Covehithe (3 km south of Benacre) early in the 19th century. Previous sediment transport experiments and modelling studies have demonstrated a net southerly transport direction on this coastline, yet the foreland has continued to migrate northward over several centuries. Local reversals in sediment transport direction and rates are likely responsible for the northward migration of the foreland, but substantial changes in behaviour over the last 400 years suggest a close relationship between foreland dynamics and coastal configuration.

Morphodynamics and Sediment Flux in the Blyth Estuary, Suffolk, UK

Research into the dynamics of estuary morphology has been stimulated by increasing commercial, environmental and legislative pressures and by the accumulated impacts of human intervention (Roman and Nordstrom, 1996; Soulsby, 1997). Of particular concern in the UK is the impact on estuaries of sea-level rise and large-scale interventions associated with dredging and port development, flood defence and habitat restoration. Prediction of estuary response to such changes requires an understanding of present-day processes and their interaction with morphologies that are often shaped by past human activities. As Pye and Allen (2000) note, estuarine research has hitherto been characterised by narrow disciplinary foci, such that research fronts in engineering, geomorphology and Quaternary science have rarely converged. The UK Estuaries Research Programme (EMPHASYS, 2000; French et al., 2002) has advocated a more holistic and interdisciplinary perspective, combining ‘bottom up’ studies of short-term hydrodynamics and sediment movement with ‘top down’ models of larger-scale morphodynamic behaviour, such that the predictive power of physically-based simulation may be realised within a conceptual framework provided by geomorphological analysis of longer-term sedimentary function. Few estuaries have been monitored in the spatial and temporal detail needed for integrated modelling of this kind and there is a need for intensive studies encompassing a greater variety of natural and anthropogenic contexts.

Morphodynamic Behaviour of a High-Energy Coastal Inlet: Loughros Beg, Donegal, Ireland

Morphological monitoring is fundamental to the understanding of coastal morphodynamics, and should provide a comprehensive awareness of coastal behaviour in response to storms, climate, sea-level change and human activities on different scales, when supported by historical (meso-) scale examinations of coastal change.

Sediment sorting and mixing in the Camel Estuary, UK

ABSTRACT Oyedotun, T.D.T., Burningham, H. and French, J. R., 2013. Sediment sorting and mixing in the Camel Estuary, UK The Camel estuary, north Cornwall, UK, is characterised by extensive intertidal flats and saltmarsh that grade into beach and sand dunes at the mouth. This and other Cornish estuaries have received considerable attention in terms of the impact of mining (principally for Sb and Sn) on sedimentation. Significant changes in sediment supplied to these systems from the local catchment occurred as a result of mining activity. The primary impacts were on supply, sedimentology and mineralogy, and the peak of these impacts occurred in the 19th century. Although pollution and chemistry indicators have been considered extensively in past studies, very little consideration has been given to the nature of estuary-coast linkages in terms of sedimentary processes. This study focuses on the sedimentological characteristics of surface and shallow intertidal sediments within the Camel estuary system. Short (15cm) sediment cores obtained from 44 sample sites were sliced at 1cm intervals and grain size analysis (using a Malvern Mastersizer 2000) was undertaken on these subsamples. A wide range of grain size parameters is examined to explore the evidence for sediment mixing and extensive sediment transport processes within the estuarine system. Results show that the sediments are dominated by medium to fine sands throughout except in the inner estuary. Sediment is moderately well sorted in the outer and mid-estuary and poorly sorted in the inner estuary. It is possible that valley shape influences sediment transport processes and inhibits the supply and active reworking of marine sands in the inner estuary.

Gravel Spit-Inlet Dynamics: Orford Spit, UK

The Orford Spit and Ness complex on the gravel-dominated shoreline of Suffolk, eastern England comprises over 350 ha of beach ridge shoreline that diverts the channel of the Alde estuary c. 12 km southward. Centuries of progradation have formed an extensive foreland at Orford Ness, but south of this, Orford Spit has exhibited significant phases of growth and retreat which are in part linked to the dynamics of Orford Haven, the inlet and ebb-delta system at the mouth of the Alde/Ore estuary. Examination of an extended history (500 years) of this system shows a definitive reduction in scales of change over the centuries, and implies a decrease in sediment availability and transport, and a shift from sediment sink to sediment source. Spit dynamics are instrumental in the development and decay of transient lagoons and estuary-oriented spits which rely on breaching, ebb delta bypassing and changes in protection facilitated by the shifting spit.

Ecology and conservation of the rare annual Petrorhagia nanteuilii (Childing Pink) on the vegetated shingle spits of Pagham Harbour, West Sussex

Petrorhagia nanteuilii (Childing Pink), a nationally rare annual, exists at only one location in the UK on the vegetated shingle spits at Pagham Harbour, West Sussex. Primarily found in dry grassland habitats throughout Spain and Portugal, at present its only known threat in the UK is the invasive perennial, Centranthus ruber (Red Valerian); however for conservation of Petrorhagia nanteuilii to be sustainable, its presence at Pagham Harbour must be better understood. The aim of this study was therefore to investigate the local distribution and ecological associations of Petrorhagia nanteuilii in order to understand the relationships between Petrorhagia nanteuilii and the vegetated shingle communities and thereby inform their conservation. Field surveys of the shingle flora were undertaken in 2007 and 2011. Vegetation was sampled and the edaphic and physical environment was also investigated using TWINSPAN, multivariate analyses and GIS. The results of the study show that Petrorhagia nanteuilii has little association with the true vegetated shingle communities on the shingle spits. They also reveal that in recent years the species has spread rapidly across parts of the site due to a number of adaptations aiding its survival and recent shifts in conservation management that have influenced spit morphology. The ecological disconnection that exists between Petrorhagia nanteuilii and the true shingle communities means it is unlikely that management strategies will be conflicting. The study concludes that conservation of both is feasible, however for management to be sustainable, both short-term and long-term strategies must be considered.