Optically stimulated luminescence dating of large storm events in Northern Scotland

Climate changes over the Holocene have directly impacted on both coastal processes and human use of coastal areas. This paper presents results from the dating of wind blown sand deposits collected from coastal and archaeological sites in Northern Scotland. Archaeological remains are frequently found interspersed with sand deposits and represent distinct periods of occupation of settlement sites within the local landscapes. In some cases storm events sufficiently inundate the sites with sand to result in periodic abandonment. Storm events can also have dramatic results on adjacent rock coastlines, with storm boulder ridges emplaced by large waves, burying sand deposits on cliff-top sites. Work has been undertaken using a quartz SAR protocol to date sand deposition at two archaeological sites in Orkney and a cliff-top site in Shetland. These dates provide chronological information, which help to construct regional chronologies of climatic instability and environmental change and allow the SAR-OSL method to be assessed as an accurate sediment dating tool in this context. © 2003 Elsevier Science Ltd. All rights reserved

Distribution, geomorphology and lithofacies of cliff-top storm deposits: Examples from the high-energy coasts of Scotland and Ireland

Cliff-top storm deposits (CTSDs) occur on cliffs at elevations of up to 50 m above sea level at exposed sites on the deep-water coasts of the British Isles. This study examines the distribution, geomorphology and lithofacies of CTSDs at sites from Shetland, Orkney, Caithness and the Outer Hebrides in Scotland and from the Aran Islands in Galway Bay in Ireland. CTSDs are generated largely by the quarrying of blocks from the cliff top, and transported by green water bores across cliff-top platforms and ramps to be deposited in backing ridges or as debris spreads. Maximum boulder sizes reach 48 m(3) but it is likely that much larger blocks can be quarried, prior to disintegration during transport. Eye-witness accounts and field mapping demonstrate that formation and modification of CTSDs has continued during major storms over recent decades. Recent CTSDs bury a range of man-made debris but older deposits lack this and instead show weathering effects that indicate a longer residence time. In Shetland OSL dates on intercalated sands suggest that the oldest CTSDs date from similar to 800 AD. Radiocarbon dates on shell buried inside CTSD ridges relate to major storms between 1700 and 1900. CTSDs represent an overlooked archive of storm sedimentation that has great potential for the elucidation of local storm chronologies. CTSDs also provide evidence of wave impacts on any part of the cliff face or top, in fundamental contrast to the concentration of wave action at the cliff foot implicit in traditional models of the erosion of rock coasts. (c) 2006 Elsevier B.V. All rights reserved.</p

Rock armour for birds and their prey: ecological enhancement of coastal engineering

The authors present key design, construction and ecological enhancement criteria for sustainable coastal defence structures at Hartlepool, UK, a high-energy wave climate. Such ‘ecologically favourable’ coastal defences fulfil the habitats directive and key engineering and cost criteria. Bird, rocky intertidal ecological and biogeomorphological data underpin recommendations for ‘passive’ enhancement mitigation to maximise ecological potential involving rock armour material choice (partially enhanced) and its smart positioning (enhanced). Within 12–18 months of installation, key intertidal species (e.g. limpets, barnacles, fucoid seaweeds) had successfully colonised the rock revetment, matching the initial baseline biotope. However, species abundance and overall mobile and sessile species were not significantly different between the two enhanced treatments after 12–18 months. Importantly, key prey species (the limpet, Patella vulgata) on enhanced rock armour showed statistically significant abundances similar to the baseline shore platform and significantly higher than partially enhanced rock armour. These preliminary data show that well-chosen rock armour material and boulder enhancement using positioning can match baseline biotope conditions in 12–18 months and that for some key prey species, positioning-enhanced rock armour rapidly matches baseline conditions. This facilitates rapid rock revetment colonisation, enabling good recruitment of food species and favourable conditions for internationally designated waterbird species

Scotland's coast: Understanding past and present processes for sustainable management

The coastline of Scotland is extremely long and varied. It comprises most of the major types of coastal environment and includes machair, a sand dune system that is unique to the western seaboard of the British Isles. Such variety has its roots in the geology and sea level inheritance of Scotland and demonstrates that long‐term processes still exert a profound influence on coastal form and functioning. Understanding how these processes affect the coast and influence such diversity is essential to efficient coastal management, although it is also imperative that the vision, strategy and political will to deliver such management are also in place