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Legislation introduced through the Marine (Scotland) Act 2010 and the Marine and Coastal Access Act 2009 will enable Scottish Ministers to establish Nature Conservation Marine Protected Areas (MPAs) within Scottish territorial and offshore waters. Guidelines for the selection of MPAs in waters adjacent to Scotland have been drafted by Marine Scotland, Scottish Natural Heritage (SNH) and the Joint Nature Conservation Committee (JNCC). These guidelines highlight the need to identify the key biodiversity and geodiversity areas in Scottish waters through a robust scientific framework with supporting justification. This report focuses on the latter theme, namely the identification of key geodiversity areas in Scottish waters. It is the second in a series of four reports that together support the development of a wider process to define MPA search locations. Section 2 of this report outlines the development of a methodology to prioritise key geodiversity areas in Scottish waters. This methodology is closely based on the Geological Conservation Review (GCR) scientific framework for the identification and prioritisation of important aspects of Earth heritage in the terrestrial environment. However, subtle amendments to the existing GCR methodology were introduced in order to ensure consistency with the Scottish MPA selection guidelines. These guidelines prioritise areas that: (i) contain key features considered of national or international importance; (ii) contain features considered to be under threat and / or subject to rapid decline; and/or (iii) are of functional significance for the overall health and diversity of Scottish Seas. Section 3 of this report provides details of the key geodiversity areas identified in Scottish waters. The list of key geodiversity areas was compiled using the GCR-style scientific framework and is based on expert judgement and the recommendations from a workshop in February 2010 attended by a range of leading Earth scientists with expertise i

Detailed analyses of recently collected bathymetric and sparker seismic data, support a new interpretation of the Landes Plateau field of sediment waves located on the Aquitaine upper continental slope (Bay of Biscay). The wave geometry, previously described as the result of a major sediment failure, is interpreted as a structure with a complex origin including the interaction of depositional and gravity deformation processes. Depositional processes are mainly recorded by the upslope migrating pattern of the waves resulting from oblique or sigmoid downlap reflections on the upslope flank of the waves and by toplapping and truncated reflections on the downslope flank. Hemipelagic and turbiditic sedimentation may be involved in the wave building as well as contouritic processes that could be related to the existing northward polar current and internal waves. Gravity deformations are syndepositional, discontinuous and of low amplitude, affecting thick layers which alternate with undeformed layers. They seem to correspond to gentle sediment creeping or stretching associated with minor listric or compaction-like faults, and possible limited back rotation of sediment blocks. These multi-process generated sediment waves could be rather common on the continental margins as they could have been mistaken with either depositional or deformational structures.

The Lofoten Basin Channel forms one of two major submarine channels on the Norwegian margin of the Polar North Atlantic. The channel system connects upslope with the Andøya Canyon which is the only canyon to cut back across the continental shelf in this region. High-resolution geophysical records, including multibeam swath–bathymetric and TOBI side-scan sonar data, show that the distal part of the channel system is braided and connects to a low-gradient (0.01°), channel-mouth lobe on the abyssal plain of the Lofoten Basin. Geophysical data indicate that the channel floor is composed of sandy material deposited by turbidity currents. These turbidity currents spilled out over the channel sides to deposit acoustically stratified sediment in the channel levees. Side-scan sonar data supplemented by sediment cores indicate that the channel-mouth lobe is sandy in composition. The Lofoten Channel and its associated channel-mouth lobe is therefore related to turbidity current activity and formation of the system appears to pre-date the Holocene. Morphological variation between the upper reaches of the Andøya Canyon/Lofoten Channel system and the submarine channels of the Greenland Basin is proposed to relate to differences in the nature of the flows feeding both systems. The Andøya Canyon/Lofoten Channel system bears strong similarities to some mid- and low-latitude submarine fans with respect to its morphology and architecture.

The sedimentary processes and evolution of a presumably old but still relatively recent active canyon-fed sandy turbidite system on the Norwegian continental margin, the Andoya Canyon - Lofoten Basin Channel system, were studied using high-resolution seismic, deep-towed side-scan sonar records and cores (gravity and vibro cores). The canyon has a length of about 40 km and represents a continental slope incision of up to 1100 m. From the canyon mouth, a deep-sea channel up to 30 m deep and 3 km wide continues for approximately 200 km into the deepest part of the Lofoten Basin. The most recent activity of this system was deposition of coarse-grained sediments from turbidity currents as indicated by sediment waves on the canyon floor, thin sand layers within the levees and a sandy lobe at the channel mouth. From this modern system we suggest that there are a number of features that could be of relevance for hydrocarbon exploration of deep-water turbidite systems: a) this canyon-fed system probably received sand from piracy of shelf sediments and/or canyon wall erosion, b) the sandy deposits are located in the deepest part of the basin, about 200 km outside the canyon mouth, c) the sandy lobe is connected to the source area by a straight channel with poorly developed mud-rich levees, d) the sandy deposits have a sheet-like or tabular geometry, e) post-depositional deformation of the sand could be widespread suggesting rapid sand deposition. Thus, modern, canyon-fed sandy turbidite systems provide additional data relevant for future hydrocarbon prospecting in deep-water areas.

A survey of the northeastern margin of the Rockall Trough on the Irish margin examined the transition from shelf edge to basin floor, in morphology and sedimentary activity, of a deeply incised submarine canyon system, the Donegal Bay submarine canyon. The survey produced superb 3D profiling of the canyon along its entire length, marking a transition from ‘cauliflower’ shaped head region with numerous tributary gullies feeding into one main canyon, to a single trunk canyon. This canyon, with an initial combined width and depth of > 17 km and > 800 m in the ‘cauliflower’ head area, decreases rapidly to > 4.5 km wide and > 450 m deep after the zone of tributary confluence. Eighteen kilometers further down dip, the canyon loses topographic expression as it approaches the lower rise and floor of the Rockall Trough. Degrees of recent sedimentary activity are evaluated by comparing side scan sonar systems of different frequency, and thus of different penetration sub sea, and by ground-truthing using drop (gravity) cores. The canyon was a very active system, dominated by sand transportation towards the floor of the Rockall Trough, along the slope as coarse-grained contourite, or as sand spillover from the shelf. Sand was also deposited as overbank deposits outside the main head region of the canyon, presumably by large volume turbidity currents and more active lateral gullies. The head area of the canyon system has been progressively cut off from sand source by progressive sea level rise since the last glaciation. Sand was locally deposited on terraces but not in the overbank area. Less frequent, lower volume and finer grained turbidity currents have become more common in the system. The initial sand and bypass-dominated system with small sediment waves, which may be gravels, has become dominated by muddy debrites in the lower reaches and by slumps in the upper reaches. Slumping in those upper reaches leads to ponding of sand in the head and upper reach areas, with only ve

The most extensive systems of submarine channels on the continental margins of the Norwegian–Greenland Sea occur in the Greenland Basin (72–75jN). Geophysical records show that these channels are up to 100-m deep, 4-km wide, and extend for about 300 km from the middle continental slope off Northeast Greenland to the abyssal depths of the basin. Mass-wasting deposits in the form of debris flows and turbidity currents, as well as hemipelagic sediments, dominate sediment cores recovered from the channels. Radiocarbon dates indicate that debris flow and turbidity current activity in the channels had ceased by 13,000 years BP and sedimentation rates show a corresponding order of magnitude decrease after this time. Masswasting in the submarine channels of the Greenland Basin therefore relates to full-glacial and deglacial conditions. This implies a more extensive Late Weichselian ice sheet in Northeast Greenland than traditionally thought. The ice sheet extended onto the outer continental shelf and may have reached the shelf edge, delivering debris and sediment-laden meltwater onto the upper slope. Channel formation is most likely the product of turbidity-current activity during successive glaciations of the Northeast Greenland continental shelf. Holocene sediments from the channel systems are predominantly of hemipelagic origin and formed in a low energy, ice distal environment. The low gradient ( < 1j) channels of the Greenland Basin are therefore a glacially influenced sedimentary system. Contrasts in slope morphology and sediment architecture between the Greenland Basin and trough-mouth fans elsewhere in the Norwegian–Greenland Sea are not the result of variations in slope gradient. Rather, these contrasts reflect the interplay between bedrock lithology of the continental shelf, rates of sediment delivery, sediment texture, meltwater volume and relative size of ice-sheet drainage basins.

The distribution of deposits, sediment transport pathways and processes on the lower Monterey Fan channel and channelmouth lobe (CML) are studied through the integration of GLORIA and TOBI sidescan sonar data with 7-kHz subbottom profiler records and sediment cores for ground-truthing. The lower Monterey channel is characterised by an up to 30-m-deep channel with poorly developed levees and alternating muddy and silty muddy overbank deposits. The channel is discontinuous, disappearing where gradients are less than about 1:350. Ground-truthing of the large CML shows that the entire CML is characterised by widespread deposits of generally fine sand, with coarser sand at the base of turbidites. Sand is particularly concentrated in finger-like areas of low-backscatter intensity and is interpreted as the result of non-turbulent sediment-gravity flows depositing metres thick massive, fine sand. TOBI sidescan sonar data reveal recent erosional features in the form of scours, secondary channels, large flow slides, and trains of blocks at the distal end of the CML. Erosion is probably related to increasing gradient as the CML approaches Murray Fracture zone and to differential loading of sandy submarine fan deposits onto pelagic clays. Reworking of older flow slides by sediment transport processes on the lobe produces trains of blocks that are several metres in diameter and aligned parallel to the flow direction.

Seismic profiles, sidescan sonar data, bottom photography and sampling proved for the first time that there are giant carbonate mounds (bioherms) in the Rockall Trough. The Pelagia Mounds, on the northern Porcupine Bank, are relatively isolated whereas most of the Logachev Mounds, on the southeast Rockall Bank, form a field of closely spaced, contiguous mounds. They are all found on the upper slope at depths between about 500 and 1200 m and as a result of this study about 500 have been mapped. They have a variety of shapes and the larger ones are very steep-sided, up to 350 m high and 2 km wide at the base. Sediment samples show that the mounds consist of pale coloured muds, mainly aragonite, usually with live and/or dead cold-water corals at the seafloor and with buried dead corals. Coral thickets appear to be detected as a brush-like signature on high resolution profiles and as a speckled pattern on high resolution sidescan sonar records. Shelly sands are found on the seabed between the mounds. Currents in the mound areas are strong enough to transport sands along slope as medium-sized sand waves and to prevent pelagic deposition, thus providing surfaces for initial coral settlement by the winnowing of fines to leave glacial dropstones and exposed rocks. These observations show that the poleward-directed upper slope current of the eastern North Atlantic extends further south than hitherto known and that there is a southwesterly directed current on Rockall Bank. There are waves on the Logachev Mounds, with a wavelength of about 20–30 m, that are thought to be moulded in carbonate muds by across-slope directed internal tidal currents and/or cascading currents. Mounds develop above erosional surfaces seen on seismic data. The huge amount of carbonate mud seems to be produced by the rapid growth and breakdown of cold-water corals living in a very favourable environment. Intermediate nepheloid layers formed upstream by the strong currents may provide the food source fo

Recent multibeam bathymetry and acoustic imagery data provide a new understanding of the sedimentary system located in the Gulf of Cadiz which is under the influence of a strong current, the Mediterranean Outflow Water (MOW). When it comes out from the Strait of Gibraltar, the MOW is either channelled along major or secondary channels, or spills over a sedimentary levee. Frequent earthquakes and the constant current shearing generate widespread sediment deformation and instability of contourite deposits. Secondary channels can form by retrogression following an initial failure. At their mouth, sediment accumulates in the form of small sandy contourite lobes. These observations suggest that the Gulf of Cadiz system shares many similarities with channel-levee complexes formed by turbidity current activity. The main difference is that, in the Gulf of Cadiz, the main process is a strongly flowing saline current which locally interacts with gravity processes.

The morphology and internal structure of sand shoals and sandbanks around a coastal headland (Portland Bill, southern UK) are described on the basis of sidescan sonar and high-resolution seismic data sets. Morphological and architectural evidence, combined with the spatial distribution and nature of the bedrock surface, indicates that the evolution of these deposits, especially the sandbanks, may not only be hydrodynamically controlled but also morphologically controlled. The internal structure of the sand shoals reveals a simple pattern of clinoforms dipping in the same direction as their steeper profile. In contrast, the internal structure of the sandbanks reveals that their lower seismic units consist of a sedimentary core interpreted as the remains of a lowstand deposit or an early stage of the bank development under different prevailing hydrodynamic conditions. The present morphology of the sandbanks is represented by upper seismic units characterized by large-scale sandwave foresets dipping at 6-8°. The nature and morphology of the bedrock surface may also influence the development of sandbanks in some cases. For example, to the west of Portland Bill, the morphology of the bedrock surface (basal reflector) restricts the development of the Portland Bank. This information may explain the asymmetric evolution of sandbanks around Portland Bill.