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This paper presents a detailed glacial Main Map of the Great Glen region of Scotland, UK, covering an area of over 6800 km2 extending from 56°34′7″ to 57°41′1″ N and from 3°44′2″ to 5°33′24″ W. This represents the first extensive mapping of the glacial geomorphology of the Great Glen and builds upon previous studies that conducted localised field mapping or ice-sheet wide mapping using remote sensing. Particular emphasis is placed on deriving medium-scale glacial retreat patterns from these data, and examining differences in landsystem assemblages across the region. Features were typically mapped at a scale of 1:8000 to 1:10,000 and will be used to investigate the pattern and dynamics of the British-Irish Ice Sheet during deglaciation. Mapping was conducted using the NEXTMap digital terrain model. In total, 17,637 glacial landforms were mapped, with 58% identified as moraines, 23% as meltwater channels, 10% as bedrock controlled glacial lineations, 3% as eskers, 2% as cirques or arêtes, 2% as kame topography or kame terraces, and 1% as drumlins. Additionally, 10 palaeo-lake shorelines were identified. Complex landform assemblages in the form of streamlined subglacial bedforms, moraines and glaciofluvial features exist across the region. Extensive subglacial meltwater networks are found over the Monadhliath Mountain Range. Transverse and longitudinal moraine ridges generally arc across valley floors or are located on valley slopes respectively. Hummocky moraines are found almost exclusively across Rannoch Moor. Finally, eskers, meltwater channels and kame landforms form spatial relationships along the axis of Strathspey. These glacial landsystems reveal the dynamics and patterns of retreat of the British-Irish Ice Sheet during the last deglaciation.

Mega-scale glacial lineations (MSGLs) are the largest flow parallel bedforms produced by ice sheets and are formed beneath rapidly-flowing ice streams. Knowledge of their characteristics and genesis is likely to result in an improved understanding of the rate at which ice and sediment are discharged by ice sheets, but there is little consensus as to how they are formed and there are few quantitative datasets of their characteristics with which to formulate or test hypotheses. This paper presents the results of a remote sensing survey of ∼46,000 bedforms on the Dubawnt Lake palaeo-ice stream bed, focussing on a central transect of 17,038 that includes highly elongate bedforms previously described as MSGLs. Within this transect, lineations exceed 10 km in length (max. >20 km) and 23% have elongation ratios >10:1 (max. 149:1). Highly elongate features are interspersed with much shorter drumlin-like features, but longer bedforms are typically narrower, suggesting that their length develops more quickly than, or at the expense of, their width. Bedforms are broadly symmetrical in plan-form and have a preferred lateral spacing of 50–250 m, which implies a regular, rather than random, pattern of corrugations. Comparison with drumlins reveals that the more attenuated MSGLs simply extend the ‘tail’ of the distribution of data, rather than plotting as a separate population. Taken together, this supports the idea of a subglacial bedform continuum primarily controlled by ice velocity, but existing hypotheses of MSGL formation are either not supported, or are insufficiently developed to explain our observations. Rather, we conclude that, under conditions of rapid ice flow, MSGLs attain their great length relatively quickly (decades) through a probable combination of subglacial deformation, which attenuates ridges, and erosional processes that removes material from between them.

Mega-scale glacial lineations (MSGLs) are highly elongate, subglacial landforms produced beneath zones of fast-flowing ice. While qualitative data on their morphology have existed for several decades, studies of their composition and sedimentology are comparatively rare. Sediment exposures along the course of the Finnie River in Nunavut, northern Canada, provide a window into the internal stratigraphy and sedimentology of MSGLs formed by the Dubawnt Lake Palaeo-Ice Stream during regional deglaciation of the Laurentide Ice Sheet. Stratigraphic sections record evidence for an initial advance of ice into the study area followed by ice sheet recession and deposition of glacifluvial and glacilacustrine outwash. Subsequently, the Dubawnt Lake Palaeo-Ice Stream overrode and reworked this outwash subglacially forming an ‘MSGL till’. This till comprises a sandy, red diamicton facies, forming the core of the MSGL ridges and containing variably deformed lenses, stringers and rafts of outwash. The sedimentology of this diamicton is consistent with an origin as a glacitectonite and hybrid till formed by a combination of non-pervasive subglacial sediment deformation and lodgement. Facies variations from stratified to massive diamicton reflect, in turn, variations in strain and subglacial transport distance. The occurrence of stratified glacifluvial sediments within these ridges and the well-preserved nature of many of the sandy inclusions within the diamicton imply relatively short transport distances and incomplete mixing. MSGLs under the Dubawnt Lake Palaeo-Ice Stream formed through a combination of subglacial erosion and deposition. This included non-pervasive, subglacial sediment deformation and the reworking of pre-existing sediment depocentres during streaming flow. These results highlight the importance of sediment supply to MSGL formation with the presence of abundant pre-existing sediments which were subsequently overridden being critical to lineation formation.

Paleoenvironments during the late Younger Dryas through early Holocene retreat of the Greenland Ice Sheet from the outer shelf in the Disko Trough system of central West Greenland were investigated via lithofacies, foraminifera, dinocysts and sediment provenance analyses in radiocarbon-dated sediment cores from the upper slope (JR175-VC35) and outer shelf (JR175-VC20 and HU2008029-070CC). Core data show that the ice margin retreated rapidly from the outer shelf by calving, beginning by 12.2k cal a BP under cold paleoceano- graphic conditions with up to 11 months of sea-ice. Ice retreat into Disko Bugt was well underway by 10.9k cal a BP. Enhanced ice-sheet ablation in Disko Bugt and elsewhere along the West Greenland coast is inferred from cold glacial marine conditions associated with high sedimentation rates between 10.9 and 9.5k cal a BP on the outer shelf. Glacial marine conditions are recorded on the outer shelf until 7.8k cal a BP. Detrital carbonate-bearing sediments rich in >2-mm clasts deposited between 11.6 and 10.6k cal a BP indicate that icebergs calved from northern Baffin Bay ice margins were melting and releasing sediments along West Greenland while the Greenland Ice Sheet margin was retreating into Disko Bugt. Copyright # 2013 John Wiley & Sons, Ltd.

As John Shaw has repeatedly challenged our interpretations of the glacial geomorphology of western Canada, there are now numerous examples in the literature of our responses to his charges of misrepresentation and/or under-utilization of his work (Benn and Evans, 2006; Evans et al., 2006a, 2008; Evans, 2010; O Cofaigh et al., 2010a). We continue to defend our position by highlighting the fact that we have, at all stages of our research, adhered to the principle of adopting the interpretation that requires the least assumptions.

We present an 8000-year history spanning 650km of ice margin retreat for the largest marine- terminating ice stream draining the former British-Irish Ice Sheet. Bayesian modelling of the geochronological data shows the ISIS expanded 34.0-25.3ka, accelerating into the Celtic Sea to reach maximum limits 25.3-24.5ka before a collapse with rapid marginal retreat to the northern Irish Sea Basin (ISB). This retreat was rapid and driven by climatic warming, sea-level rise, mega-tidal amplitudes and reactivation of meridional circulation in the North Atlantic. The retreat, though rapid, is uneven, with the stepped retreat pattern possibly a function of the passage of the ice stream between normal and adverse ice bed gradients and changing ice stream geometry. Initially, wide calving margins and adverse slopes encouraged rapid retreat (! 550m a " 1 ) that slowed (! 100m a " 1 ) at the topographic constriction and bathymetric high between southern Ireland and Wales before rates increased (! 200m a " 1 ) across adverse bed slopes and wider and deeper basin configuration in the northern ISB. These data point to the importance of the ice bed slope and lateral extent in predicting the longer-term (>1000 a) patterns and rates of ice-marginal retreat during phases of rapid collapse, which has implications for the modelling of projected rapid retreat of present-day ice streams. Copyright # 2013 John Wiley & Sons, Ltd.

Radiocarbon ages on sub-till organic material suggest that Ireland was largely ice-free until ~32 ka, after which the last Irish Ice Sheet (IIS) thickened to cover all mountain summits. Offshore moraines and related evidence indicate that the IIS extended westward to the Atlantic shelf break, eastwards into the Irish Sea Basin and southwards to the Celtic Sea shelf edge. Expansion of the IIS to its offshore limits was asynchronous: it apparently reached its limits on the Malin Sea shelf by ~27 ka, but after ~25 ka on the Porcupine Spur and possibly as late as ~24–23 ka on the Celtic Sea shelf. The ice-sheet margin appears to have retreated to the present coastline of Ireland by ~20 ka, and probably earlier in SE Ireland. Nested offshore and onshore moraines and the alignment of successive generations of subglacial bedforms demonstrate that retreat was interrupted by readvances and characterised by migration of ice divides and switching flow directions. Only two readvances are securely dated: the Clogher Head Readvance (~18.4 ka) in northern Ireland and the Killard Point Readvance (~17.3–16.6 ka) along the NE coast. Following the Killard Point Readvance, Scottish ice advanced across the north coast (the East Antrim Coastal Readvance) sometime around or after ~16.5 ka. It is likely that low ground was completely deglaciated following rapid warming at ~15.4–15.0 ka or slightly later. Small glaciers formed in some mountain areas during the Nahanagan (Younger Dryas) Stadial of ~12.9–11.7 ka, but some cirque moraines formed much earlier.

The deglacial history and oceanography of Uummannaq Trough, central West Greenland continental shelf, was investigated using foraminiferal, sedimentological, and bathymetric records together with a radiocarbon chronology, providing a timeline for the retreat of glacial ice after the Last Glacial Maximum (LGM). To map ice stream retreat, data were collected from cores from the outer (JR175-VC45 and JR175-VC43) and inner (JR175-VC42) Uummannaq Trough. A large ice stream, fed by confluent glaciers draining the interior of the Greenland Ice Sheet, extended across the outer shelf during the LGM and was in retreat by 15.0 cal kyr BP. Foraminiferal data indicate that the ‘warm’ West Greenland Current (WGC) was established prior to 14.0 cal kyr BP, which is the hitherto earliest record of Atlantic Water found on the West Greenland shelf. For each of the cores, foraminifera indicate that ice sheet retreat was followed quickly by incursion of the WGC, suggesting that the warm water may have enhanced ice retreat. Prior to the Younger Dryas cold event, the radiocarbon chronology indicates that the ice sheet retreated to the mid-shelf, where it subsequently stabilised and formed a large grounding-zone wedge (GZW). After the Younger Dryas, around 11.5 cal kyr BP, the ice retreated rapidly from the GZW and into the fjords.

The Uummannaq region is a mosaic of glacial landsystems, consistent with hypothesised landscape distribution resulting from variations in subglacial thermal regime. The region is dominated by selective linear erosion which has spatially and altitudinally partitioned the landscape. Low altitude areas are dominated by glacial scour, with higher elevations are dominated by plateaux or mountain valley and cirque glaciers. The appearance and nature of each landscape type varies locally with altitude and latitude, as a function of bedrock geology and average glacial conditions. Selective linear erosion has been a primary control on landscape distribution throughout Uummannaq, leading to plateau formation and the growth of a coalescent fjord system in the Uummannaq region. This has allowed the development of the Uummannaq ice stream’s (UIS) onset zone during glacial periods. Fjord development has been enhanced by a down-stream change in geology to less-resistant lithologies, increasing erosional efficiency and allowing a single glacial channel to develop, encouraging glacier convergence and the initiation of ice streaming. The landscape has been affected by several periods of regional uplift from 33 Ma to present, and has been subject to subsequent fluvial and glacial erosion. Uplift has removed surfaces from the impact of widespread warm-based glaciation, leaving them as relict landsurfaces. The result of this is a regional altitude-dependant continuum of glacial modification, with extreme differences in erosion between high and low elevation surfaces. This study indicates that processes of long-term uplift, glacial erosion/protection, and spatial variability in erosion intensity have produced a highly partitioned landscape.

Near-seabed (

Along the West Greenland continental margin adjoining Baffin Bay, bathymetric data show a series of large submarine fans located at the mouths of cross-shelf troughs. One of these fans, termed here ‘Uummannaq Fan’, is a trough-mouth fan built largely by debris delivered from a fast-flowing outlet of the Greenland Ice Sheet during past glacial maxima. Cores from this fan provide the first information on glacimarine sedimentary facies within a major West Greenland trough-mouth fan and on the nature of Late Weichselian–Holocene glacigenic sediment delivery to this region of the Baffin Bay margin. Glacigenic debris flows deposited on the upper slope and extending to at least 1800 m water depth in front of the trough-mouth are related to the remobilization of subglacial debris that was delivered onto the upper slope at times when an ice stream was positioned at the shelf edge. In contrast, sedimentary facies from the northern sector of the fan are characterized by hemipelagic and ice-rafted sediments and turbidites; glacigenic debris flows are notably absent in cores from this region. Quantitative X-ray diffraction studies of the

High resolution multibeam swath bathymetric data acquired from the Rockall Bank reveal an abundance of linear to slightly sinuous seabed incisions. These features, interpreted as relict iceberg scours, provide for the first time evidence that the Rockall Bank was intensively scoured by iceberg keels. While the shallower portion of the Rockall Bank lacks evidence of iceberg scouring, on the western and southern flanks (between 250 and 450 m water depth) the seabed is almost completely covered by thousands of cross-cutting scours. More isolated scours, up to 800 m wide and 25 km long are also observed down to nearly 600 m water depth. Based on a full glacial sea level low stand of 120 m, these isolated scour marks must have been carved bygigantic icebergs with keels up to 500 m deep and able to create incisions up to 15 m deep in the seabed. Analysis of scour orientation, length, width, and depth indicates that these mega-icebergs were likely calved from large, fast-flowing ice sheet outlets draining circum-North Atlantic ice sheets. Prevailing scour orientations suggest a number of possible ice sheet sources, including southeast and southern Greenland and the Donegal-Barra ice stream of the last British–Irish Ice Sheet. The bimodal distribution of the scour depth observed across the Rockall Bank suggest either different icebergs provenances or physical and climatic controlson icebergs draft.

The morpho-stratigraphic subdivision of the surficial glacial drifts of Ireland into ‘Older Drift’ and ‘Younger Drift’ is a long-standing convention in Irish Quaternary studies. Across southern Ireland a broad swath of terrain has traditionally been interpreted as Munsterian (penultimate glaciation) in age and large end moraine complexes bordering this zone of ‘Older Drift’ such as the ‘South Ireland End Moraine’ have long been regarded as marking the limit of the Late Midlandian (last glaciation) ice sheet. Sedimentary sequences exposed along the south coast of Ireland provide a window into the stratigraphy of the ‘Older Drift’ and have been studied for over a century. The present paper supports a fundamental revision of the traditional interpretation of ice sheet limits in southern Ireland and argues for an extensive last Irish Ice Sheet which covered much of the area of the Older Drift at the Last Glacial Maximum. The basis for this revision is threefold. Firstly, nineteen new optically stimulated luminescence (OSL) dates on the Courtmacsherry Raised Beach and overlying shallow marine sands demonstrate that on the south coast the beach and shallow marine sands formed during marine isotope stages 4–3. Secondly, AMS radiocarbon dates on reworked shells from the ‘Irish Sea Till’, demonstrate that this till and overlying ‘inland’ tills from central and SW Ireland were formed after ∼24 cal ka BP. Thirdly, new OSL dates of 24–21 ka BP from deglacial outwash overlying the Irish Sea Till. Collectively these data are consistent with a last glaciation age for the glacigenic sequence along the south coast of Ireland, thus supporting a fundamental revision of the age of the Older (Munsterian) Drifts of southern Ireland. Most of southern Ireland was glaciated during the LGM and the moraine belts which have traditionally been interpreted as marking the last glacial limit such as the South Ireland End Moraine are reinterpreted here as recessional features formed during ice sheet retreat.

Multibeam swath bathymetry data collected through the Irish National Seabed Survey provides direct evidence for extensive glaciation of the continental shelf off northwest Ireland. Streamlined subglacial bedforms on the inner shelf record former offshore-directed ice flow. The major glacial features, however, consist of well developed, nested arcuate moraines which mark the position of former ice sheet margins on the shelf. Distal to these moraines, on the outermost shelf, prominent zones of iceberg ploughmarks give way into a well developed system of gullies and canyons which incise the continental slope. The large-scale, nested, arcuate moraines record the episodic retreat, probably punctuated by minor readvances or oscillations, of a lobate grounded ice sheet across this sector of the continental shelf during deglaciation. Initial retreat from the outer shelf was associated with an episode of ice sheet break-up and calving as recorded by extensive zones of iceberg ploughmarks distal to the outermost moraine. It is conceivable that this initial phase of retreat could have been driven by rising sea level. The data indicate a major reorganisation of the Irish Ice Sheet on the northwest shelf during deglaciation; an initial elongate ice sheet configuration extending along the shelf edge changed to a pronounced lobate form during retreat. Consideration of dated, marine stratigraphic records from the wider northwest margin suggests that ice sheet advance to the shelf edge likely occurred at about 29–27 cal ka BP, but that retreat from this shelf edge position did not take place until after 24 cal ka BP. Large-scale contrasts in continental margin morphology west of Ireland, from trough mouth fans in the north to gully/canyon systems further to south, reflects a combination of factors including spatial variations in sediment flux related to palaeo-glaciology.

The extent and behaviour of the central West Greenland sector of the Greenland Ice Sheet (GIS) during the Last Glacial Maximum (LGM) and the following deglaciation remains poorly constrained. To investigate deglacial marine environments and sedimentary processes in an area fed by several LGM ice streams we now report findings from a 3.5 kHz sub-bottom profiler survey acquired in and around Disko Bay in 2009. Sediment thicknesses and volumes in three glaciated areas, Disko Bay, southern Vaigat and Egedesminde Dyb, are fully constrained for the first time. Acoustic facies types and distributions were also mapped. The largest sediment thicknesses (256 m) and widest variation in acoustic character was observed in Disko Bay adjacent to the mouth of Jakobshavns Isfjord. Significant sediment thicknesses were also observed in isolated basins in the Egedesminde Dyb trough and in a trough in southern Vaigat Strait (up to 110 m). Given low modern sedimentation rates, these thick sediment packages are inferred to record the retreat of glaciers from the middle shelf through Disko Bay and into both the Jakobshavns and Torssukatak fjord systems in central West Greenland. Our results highlight similarities in deglacial sedimentary processes across the study area, when the margins of retreating glaciers supplied large volumes of sediment to the marine environment from sediment-laden meltwater plumes and melting icebergs. We estimate the sediment flux for the palaeo-Jakobshavn ice stream while the ice margin was stable at a fjord-entrance sill to be 1.6–3.6 × 10 7 m 3 a − 1 . Assuming a flux at the upper end of our range for the Torssukatak fjord system requires the grounded ice margin to be stable for about 450 years during retreat. The sediment fluxes we estimate are within the range of previously calculated fluxes for other Arctic and Antarctic ice streams and suggest that large volumes of meltwater and sediment were available at the base of the outlet glaciers during deglaciation, even during periods of quasi-stability. Retreat of the ice margins into the fjord systems is characterised by a rapid transition to ice-distal sedimentation by rainout of iceberg-rafted detritus (IRD) and hemipelagic material; accumulation rates drop to ~ 2 mm a − 1 . This study demonstrates the variability in glacimarine processes and environments on high-latitude continental margins and highlights the importance of local factors, such as bedrock morphology, as well as glacio-dynamic factors, on sedimentation.

The central sector of the last British–Irish Ice Sheet (BIIS) was characterised by considerable complexity, both in terms of its glacial stratigraphy and geomorphological signature. This complexity is reflected by the large number and long history of papers that have attempted to decipher the glaciodynamic history of the region. Despite significant advances in our understanding, reconstructions remain hotly debated and relatively local, thereby hindering attempts to piece together BIIS dynamics. This paper seeks to address these issues by reviewing geomorphological mapping evidence of palimpsest flow signatures and providing an up-to-date stratigraphy of the region. Reconciling geomorphological and sedimentological evidence with relative and absolute dating constraints has allowed us to develop a new six-stage glacial model of ice-flow history and behaviour in the central sector of the last BIIS, with three major phases of glacial advance. This includes: I. Eastwards ice flow through prominent topographic corridors of the north Pennines; II. Cessation of the Stainmore ice flow pathway and northwards migration of the North Irish Sea Basin ice divide; III. Stagnation and retreat of the Tyne Gap Ice Stream; IV. Blackhall Wood–Gosforth Oscillation; V. Deglaciation of the Solway Lowlands; and VI. Scottish Re-advance and subsequent final retreat of ice out of the central sector of the last BIIS. The ice sheet was characterised by considerable dynamism, with flow switches, initiation (and termination) of ice streams, draw-down of ice into marine ice streams, repeated ice-marginal fluctuations and the production of large volumes of meltwater, locally impounded to form ice-dammed glacial lakes. Significantly, we tie this reconstruction to work carried out and models developed for the entire ice sheet. This therefore situates research in the central sector within contemporary understanding of how the last BIIS evolved over time.

We review the geomorphological, sedimentological and chronological evidence for palaeo-ice streams on the continental shelf of Antarctica and use this information to investigate basal conditions and processes, and to identify factors controlling grounding-line retreat. A comprehensive circum-Antarctic inventory of known palaeo-ice streams, their basal characteristics and minimum ages for their retreat following the Last Glacial Maximum (LGM) is also provided. Antarctic palaeo-ice streams are identified by a set of diagnostic landforms that, nonetheless, display considerable spatial variability due to the influence of substrate, flow velocity and subglacial processes. During the LGM, palaeo-ice streams extended, via bathymetric troughs, to the shelf edge of the Antarctic Peninsula and West Antarctica, and typically, to the mid-outer shelf of East Antarctica. The retreat history of the Antarctic Ice Sheet since the LGM is characterised by considerable asynchroneity, with individual ice streams exhibiting different retreat histories. This variability allows Antarctic palaeo-ice streams to be classified into discrete retreat styles and the controls on grounding-line retreat to be investigated. Such analysis highlights the important impact of internal factors on ice stream dynamics, such as bed characteristics and slope, and drainage basin size. Whilst grounding-line retreat may be triggered, and to some extent paced, by external (atmospheric and oceanic) forcing, the individual characteristics of each ice stream will modulate the precise timing and rate of retreat through time.

The continental margin offshore of western Ireland offers an opportunity to study the effects of glacial forcing on the morphology and sediment architecture of a mid-latitude margin. High resolution multibeam bathymetry and backscatter data, combined with shallow seismic and TOBI deep-towed side-scan sonar profiles, provide the basis for this study and allow a detailed geomorphological interpretation of the northwest Irish continental margin. Several features, including submarine mass failures, canyon systems and escarpments, are identified in the Rockall Trough for the first time. A new physiographic classification of the Irish margin is proposed and linked to the impact of glaciations along the margin. Correlation of the position and dimensions of moraines on the continental shelf with the level of canyon evolution suggests that the sediment and meltwater delivered by the British–Irish Ice Sheet played a fundamental role in shaping the margin including the upslope development of some of the canyon systems. The glacial influence is also suggested by the variable extent and backscatter signal of sedimentary lobes associated with the canyons. These lobes provide an indirect measurement of the amount of glaciogenic sediment delivered by the ice sheet into the Rockall Trough during the last glacial maximum. None of the sedimentary lobes demonstrates notable relief, indicating that the amount of glaciogenic sediment delivered by the British–Irish Ice Sheet into the Rockall Trough was limited. Their southward disappearance suggests a more restricted BIIS, which did not reach the shelf edge south of 54°23′ N. The various slope styles observed on the Irish margin represent snapshots of the progressive stages of slope development for a glacially-influenced passive margin and may provide a predictive model for the evolution of other such margins.

Glacial geological evidence of rapid ice stream retreat is important for the potential insight it can bring to understanding of contemporary rapid ice sheet change. Here, we report new chronological constraints on the deglacial history of the Marguerite Trough Ice Stream, which formerly drained part of the western margin of the Antarctic Peninsula. This ice stream has been previously identified on geomorphological grounds as an example of an outlet that underwent rapid retreat following the Last Glacial Maximum, but the precise timing of this retreat has not been conclusively determined. We obtained cosmogenic surface exposure dates on erratic boulders that record the thinning history of ice flowing into the ice stream. These dates show that the ice stream underwent >270 m of thinning very rapidly at 9.6 ka BP. The timing of ice stream thinning agrees closely with previously published data on ice shelf retreat, the age of the first post-glacial beaches, and minimum constraining ages for the onset of lacustrine sedimentation, and post-glacial sedimentation in inner shelf fjords. We compare the timing of retreat to the similarly-sized Anvers Trough ice stream further north and find that retreat in Marguerite Bay was more rapid and earlier than in the Anvers Trough. We argue that the intrusion of Circumpolar Deep Water is the most likely forcing mechanism for retreat in Marguerite Bay. A key finding of this study is that rapid retreat occurred in deep water with reverse (continent-dipping) slope but also in relatively shallow water with a positive slope. This may have implications for understanding of oceanographically-forced ice sheet change in other parts of West Antarctica.

We present results from three geophysical campaigns using high-resolution sub-bottom profiling to image sediments deposited in Loch Ness, Scotland. Sonar profiles show distinct packages of sediment, providing insight into the loch’s deglacial history. A recessional moraine complex in the north of the loch indicates initial punctuated retreat. Subsequent retreat was rapid before stabilisation at Foyers Rise formed a large stillstand moraine. Here, the calving margin produced significant volumes of laminated sediments in a proglacial fjord-like environment. Subsequent to this, ice retreated rapidly to the southern end of the loch, where it again deposited a sequence of proglacial laminated sediments. Sediment sequences were then disturbed by the deposition of a thick gravel layer and a large turbidite deposit as a result of a jo¨kulhlaup from the Spean/Roy ice dammed lake. These sediments are overlain by a Holocene sheet drape. Data indicate: (i) a former tributary of the Moray Firth Ice Stream migrated back into Loch Ness as a major outlet glacier with a calving margin in a fjord-like setting; (ii) there was significant sediment supply to the terminus of this outlet glacier in Loch Ness; and (iii) that jo¨kulhlaups are important for sediment supply into proglacial fjord/lake environments and may compose >20% of proglacial sedimentary sequences.

The timing, nature, and causes of grounded ice-sheet retreat following the Last Glacial Maximum (LGM) in Marguerite Trough, west Antarctic Peninsula, and subsequent early Holocene ice-shelf decay, are presented in this paper. We use sedimentological, foraminiferal, geotechnical, and accelerator mass spectrometer (AMS) radiocarbon data from marine cores from the mid-continental shelf, together with previously published AMS dates, to establish a sedimentological and chronological model. Initial ice-sheet retreat through the outer- and mid-shelf sectors of Marguerite Trough was under way by ca. 14 ka B.P., was rapid, and coincided with the sea-level rise of meltwater pulse 1a. An ice shelf formed during this retreat, and fine-grained, laminated muds reflecting meltwater-derived suspension settling and/or tidal pumping were deposited. During this time the ice sheet remained grounded on the inner shelf. Ice-shelf breakup and retreat of the calving front, from ca. 13.2 to 12.5 ka B.P., was slow (∼100 m a –1 ) across the outer- and mid-shelf, with calving bay conditions remaining for at least 3.5 ka. We interpret this ice-shelf decay to have been driven by an incursion of Weddell Sea Transitional Water onto the shelf. In contrast, grounding-line and ice-shelf retreat in the inner bay occurred from ca. 9.3 ka B.P. and was driven by Circumpolar Warm Deep Water encroaching onto the continental shelf. At this time the mid-shelf was an open-marine environment characterized by hemipelagic deposition. These findings highlight the importance of oceanographic controls in the breakup of Antarctic Peninsula ice shelves during the Holocene.

As the majority of the data on Quaternary sediments from the North Sea Basin are seismostratigraphical, we analysed the Elsterian Swarte Bank Formation, the Late Saalian Fisher Formation and the Late Weichselian (Dimlington Stadial) Bolders Bank Formation in order to determine genesis and provenance. The Swarte Bank Formation is a subglacial till containing palynomorphs from the Moray Forth and the northeastern North Sea, and metamorphic heavy minerals from the Scottish Highlands. The Fisher Formation was sampled from the northern and central North Sea. In the north, it is interpreted as a subglacial till, with glaciomarine sediments cropping out further south. These sediments exhibit a provenance signature consistent with the Midland Valley of Scotland, the Eocene of the North Sea Basin, the Grampian Highlands and northeast Scotland. The Bolders Bank Formation is a subglacial till containing palynomorphs from the Midland Valley of Scotland, northern Britain, and a metamorphic heavy-mineral suite indicative of the Grampian Highlands, Southern Uplands and northeast Scotland. These data demonstrate that there was repeated glaciation of the North Sea Basin during the Middle and Late Pleistocene, with ice sheets originating in northern Scotland. There was no evidence for a Scandinavian ice sheet in the western North Sea basin.

High-resolution geophysical and sediment core data are used to investigate the pattern and dynamics of former ice flow in Kvitoya Trough, northwestern Barents Sea. A new swath-bathymetric dataset identifies three types of submarine landform in the study area (streamlined landforms, meltwater channels and cavities, iceberg scours). Subglacially produced streamlined landforms provide a record of ice flow through Kvitoya Trough during the last glaciation. Flow directions are inferred from the orientations of streamlined landforms (drumlins, crag-and-tail features). Ice flowed northward for at least 135 km from an ice divide at the southern end of Kvitoya Trough. A large channel-cavity system incised into bedrock in the southern trough indicates that subglacial meltwater was present at the former ice-sheet base. Modest landform elongation ratios and a lack of mega-scale glacial lineations suggest that, although ice in Kvitoya Trough was melting at the bed and flowed faster than the likely thin and cold-based ice on adjacent banks, a major ice stream probably did not occupy the trough. Retreat was relatively rapid after 14–13.5 14C kyr B.P. and probably progressed via ice sheet-bed decoupling in response to rising sea level. There is little evidence for still stands during ice retreat or of ice-proximal deglacial sediments. Relict iceberg scours in present-day water depths of more than 350 m in the northern trough indicate that calving was an important mass loss mechanism during retreat.

Kangerlussuaq Fjord is a relatively uniform, steep-walled basin, whose floor has an almost smooth surface. Debris is supplied mainly from icebergs from the fast-flowing Kangerlussuaq Glacier. Sedimentation after iceberg release from multi-year sea ice is mainly by rain-out of fine-grained englacial debris. Streamlined glacial lineations and drumlins were produced at the sedimentary bed of an ice sheet that expanded into Kangerlussuaq Trough at the Last Glacial Maximum (LGM). Bedrock channels and crescentic overdeepenings indicate warm-based ice and free water beneath parts of the former ice sheet. Cross-cutting iceberg scour marks, which characterise outer Kangerlussuaq shelf, were produced not only during deglaciation, but also occasionally through the Holocene by deep-keeled icebergs from further north in East Greenland. The outward-convex contours of the shelf edge and slope beyond Kangerlussuaq Trough, and debris flows on the slope, suggest a glacier-influenced high-latitude fan. The distribution of streamlined subglacial landforms demonstrates that the Greenland Ice Sheet extended throughout Kangerlussuaq Fjord and reached at least 200 km across the shelf in Kangerlussuaq Trough at the LGM. Streamlined landform orientation indicates ice flow from the interior of Greenland down the axis of Kangerlussuaq Trough. There is little evidence for discrete sedimentary depocentres in the trough, implying that ice probably retreated rapidly from the outer and mid shelf during deglaciation.

Marine-geophysical and geological data from the seafloor surrounding Kong Karls Land in eastern Svalbard are used to reconstruct Late Weichselian full-glacial flow dynamics and retreat history of the Barents Sea Ice Sheet (BSIS). Grounded ice extended over the entire area during the Last Glacial Maximum (LGM) and produced streamlined sedimentary landforms in the broad bathymetric troughs that flank the Kong Karls Land archipelago. The landforms were produced in subglacial till as a result of subglacial processes at the base of the ice sheet. Drumlins and hill–hole pairs confirm that regional ice-flow was towards the east–northeast through the troughs. Based on the absence of ice-margin recessional features, deglaciation in Olga Strait, Erik Eriksen Strait and the unnamed deep northeast of Kong Karls Land appears to have been rapid in the deeper, outer parts of the troughs. In contrast, in the shallower parts of the troughs, ice recession was slower and minor readvances/still-stands of the ice margin resulted in the formation of recessional moraines. During deglaciation, temporary calving bays formed in the deeper parts of the troughs and calved icebergs were evacuated away from the ice margin through the troughs. Grounding-zone features formed in Olga Strait indicate that retreat here was gradual and punctuated by longer still-stands. The transition from a grounded ice sheet to ice-proximal settings is marked locally by a laminated mud sequence deposited from meltwater plumes from a nearby ice margin. The presence of meltwater-derived facies suggests that melting may have also been a significant ice loss mechanism during retreat. In a broader context, this study is one of the first investigations of the seafloor east of Svalbard, providing evidence that ice drained towards the east-northeast during full-glacial conditions. Ice from this part of the BSIS was an important contributor to the palaeo-ice stream in the large Franz Victoria Trough during the LGM.

The geochemical composition of Last Glacial Maximum (LGM) tills and glacitectonites in east Yorkshire and Lincolnshire was analysed to assess vertical changes in their geochemical signature with respect to the current regional stratigraphic division and generic models of till deposition. Results fail to precisely differentiate the traditional Basement, Skipsea and Withernsea till types. Instead, there is often more variability within these till types than between them. The geochemical signatures are also laterally discontinuous and are often repeated vertically at a number of sites, suggesting that the till sequences are composed of a number of lithologically distinct rafts, which have been tectonically stacked or elevated to higher levels in the sediment pile. At Dimlington the production of a glacitectonically folded and stacked moraine is proposed as a mechanism to explain the remarkably thick sequence of Withernsea Till and the repetitions in geochemical composition. We argue that the changes in till matrix geochemistry are related to changes in the dominance of ice lobes of different provenance, which reworked pre-existing Quaternary sediments, excavated local bedrock and progressively mixed these sediments with more far-travelled material from further north. The most significant implication of these findings is that the current LGM till stratigraphy of east Yorkshire and Lincolnshire is too simplified and therefore does not recognise the sedimentary and structural complexity produced by repeated onshore, possibly surging, flow by a dynamic North Sea lobe at the eastern margin of the British–Irish Ice Sheet.

The complex glacial geomorphology and stratigraphy of the Solway Lowlands (Cumbria, UK) reflects dynamic ice flow during the Main Late Devensian Glaciation, with numerous ice-flow shifts, and re-advances now recognised. The final incursion of Scottish ice into the region (Scottish Re-advance) during a late stage of deglaciation has provoked widespread debate and even scepticism arising from ill-defined marginal limits, and a paucity of landforms, sediments and dates. In an attempt to resolve some of these issues this paper has applied both geomorphological and stratigraphic techniques to critically review evidence pertaining to the Scottish Re-advance. A major deltaic landform-sediment assemblage at Holme St. Cuthbert; a thin, patchy till sheet; and eskers at Thursby and Sowerby Wood verify that Scottish ice re-advanced into the Solway Lowlands at a late stage of deglaciation. The thin, patchy till sheet associated with the re-advance is indicative of a short-lived pulse, with ice thought to have flowed rapidly across water-saturated sediment and into proglacial lakes dammed up against higher ground to the east. The Holme St. Cuthbert delta, which evolved from a subaqueous outwash fan marks a major still-stand and development of a large ice-contact lake in the vicinity of Wigton. The extent of the glaciation is difficult to elucidate, with the till sheet disparately exposed as far east as Lannercost although identification of the Blackhall Wood Re-advance Till member probably limits its SE extent to just south of Carlisle. Coeval re-advance of Lake District ice is possible given that a final stage lobate movement of ice out of the Vale of Eden and into the Solway Lowlands is now recognised, however there is no direct stratigraphic correlation or dating control.

O Cofaigh, C., Evans, D. J. A. & Hiemstra, J. F. 2010: Formation of a stratified subglacial ‘till’ assemblage by ice-marginal thrusting and glacier overriding. Boreas, 10.1111/j.1502-3885.2010.00177.x. ISSN 0300-9483. A thick sequence of glaciotectonically stacked till and outwash is preserved in a coastal embayment at Feohanagh, southwest Ireland. The sequence contains a variety of diamicton lithofacies, including laminated, stratified and massive components, but stratified diamictons dominate. Stratification/lamination is imparted by the presence of numerous closely spaced subhorizontal and anastomosing partings, which give a fissile appearance to the diamictons. Many partings are the result of sandy or thin gravelly layers within the diamictons. Some diamictons contain interbeds and lenses of sand, mud and gravel, which still preserve the original stratification. The sequence at Feohanagh is the product of a two-stage depositional process in which initial glaciolacustrine sedimentation in an ice-dammed lake was followed by glaciotectonic thrusting and overriding, during which the lake sediments were reworked and variably deformed. Similar late Quaternary sequences of glaciotectonically stacked stratified sediments and till have been described from around the coastal margins of Ireland and Britain, where they constitute glaciotectonite–subglacial traction till continuums rather than true lodgement tills as traditionally implied. Thick stratified diamicton assemblages are likely to occur in areas where steep topography provides pinning points for the glacier margin to stabilize and deliver large volumes of sediment into a glaciolacustrine or glaciomarine setting before proglacial and subglacial reworking of the sediment pile. The resulting geological–climatic unit, often defined as ‘till’, will contain a large amount of stratified and variably deformed material (laminated and stratified diamictons will be common), including intact sediment rafts, reflecting low strain rates and short sediment transport distances.

The submarine glacial geomorphology and sedimentology of the cross-shelf troughs and the adjacent continental slope around the Antarctic Peninsula and West Antarctica have been the focus of a series of marine geophysical and geological investigations over the last decade (e.g., [Shipp et al., 1999], [Canals et al., 2000], [Wellner et al., 2001], [Lowe and Anderson, 2002], [O Cofaigh et al., 2002], [Dowdeswell et al., 2004], [Heroy and Anderson, 2005], [Evans et al., 2005], [Domack et al., 2006], [Mosola and Anderson, 2006], [Wellner et al., 2006], [Dowdeswell et al., 2006], [O Cofaigh et al., 2007], O Cofaigh et al., 2008 C. O Cofaigh, J.A. Dowdeswell, J. Evans and R.D. Larter, Geological constraints on Antarctic palaeo-ice stream retreat, Earth Surface Processes and Landforms 33 (2008), pp. 513–525.[O Cofaigh et al., 2008] and [Dowdeswell et al., 2008]). These studies have interpreted sets of characteristic streamlined glacial bedforms and sediments on the shelf, which in numerous cases occur in front of modern ice streams, as largely the product of fast-flowing palaeo-ice streams that drained across the shelf during or following the last glacial maximum. A key feature of these studies is the observation of highly attenuated bedforms known as mega-scale glacial lineations (MSGL), formed in soft sediment on the outer continental shelf. These lineations are regarded as key evidence for streaming flow. In their recent paper, Shaw et al. present a radically different interpretation of the glacial geomorphology of Antarctic cross-shelf troughs in terms of catastrophic discharge of subglacial meltwater floods across the shelf. In their interpretation, MSGL are regarded as the product of erosion by turbulent meltwater flow. The following comment discusses a number of the key assertions made in their paper.

The Tyne Gap is a wide pass, situated between the Scottish Southern Uplands and the English Pennines that connects western and eastern England. It was a major ice flow drainage pathway of the last British–Irish Ice Sheet. This study presents new glacial geomorphological and sedimentological data from the Tyne Gap region that has allowed detailed reconstructions of palaeo-ice flow dynamics during the Late Devensian (Marine Isotope Stage 2). Mapped lineations reveal a complex palimpsest pattern which shows that ice flow was subject to multiple switches in direction. These are summarised into three major ice flow phases. Stage I was characterised by convergent Lake District and Scottish ice that flowed east through the Tyne Gap, as a topographically controlled ice stream. This ice stream was identified from glacial geomorphological evidence in the form of convergent bedforms, streamlined subglacial bedforms and evidence for deformable bed conditions; stage II involved northerly migration of the Solway Firth ice divide back into the Southern Uplands, causing the easterly flow of ice to be weakened, and resulting in southeasterly flow of ice down the North Tyne Valley; and stage III was characterised by strong drawdown of ice into the Irish Sea Ice Basin, thus starving the Tyne Gap of ice and causing progressive ice sheet retreat westwards back across the watershed, prior to ice stagnation

The pattern of late Weichselian (ca. 20 ka) ice flow in the northern Barents Sea is not well known, due mainly to a lack of marine data east of Svalbard. Several years with little summer sea ice have allowed acquisition of swath-bathymetric imagery of well-preserved subglacial landforms characterizing late Weichselian ice-flow directions over ∼150,000 km2 of the northwestern Barents Sea. We show that a major ice dome was located on easternmost Spitsbergen or southern Hinlopen Strait, at least 500 km west of its previously inferred position in the northern Barents Sea. This dome controlled the regional flow pattern; ice flowed eastward around Kong Karls Land into Franz Victoria Trough and north through Hinlopen Strait. An ice dome west of Kong Karls Land is required to explain the observed ice-flow pattern, but does not preclude an additional ice dome to the southeast. Discrepancies with earlier ice-sheet reconstructions reflect the lack of previous seafloor observations, with evidence limited mainly to past ice loading and postglacial rebound. The new pattern of ice-flow directions shows predominantly eastward rather than northward flow, with Franz Victoria Trough a major drainage pathway with a full-glacial balance flux of >40 km3 yr−1.

The Brampton kame belt represents one of the largest glaciofluvial complexes within the UK. It is composed of an array of landform-sediment assemblages, associated with a suite of meltwater channels and situated within a palimpsest landscape of glacial features in the heart of one of the most dynamic parts of the British–Irish Ice Sheet. Glacial geomorphological mapping and sedimentological analysis have allowed a detailed reconstruction of both the morphological features and the temporal evolution of the Brampton kame belt, with processes informed by analogues from modern ice margins. The kame belt demonstrates the development of a complex glacier karst typified by the evolution of subglacial meltwater tunnels into an englacial and supraglacial meltwater system dominated by ice-walled lakes and migrating ice-contact drainage networks. Topographic inversion led to the extensive reworking of sediments, with vertical collapse and debris flows causing partial disintegration of the morphology. The resultant landform comprises a series of kettle holes, discontinuous ridges and flat-topped hills. The Pennine escarpment meltwater network, which fed the Brampton kame belt, is composed of an anastomosing subglacial channel system and flights of lateral channels. The Brampton kame belt is envisaged to have formed during the stagnation of ice in the lee of the Pennines as ice retreated westwards into the Solway Lowlands. The formation of the Brampton kame belt also has particular conceptual resonance in terms of constraining the nature of kame genesis, whereby an evolving glacier karst is a key mechanism in the spatial and temporal development of ice-contact sediment-landform associations.

Despite over a century of research, reconstructions of the western margin of the last British-Irish Ice Sheet remain controversial. This is mainly because the ice sheet extended offshore onto the continental shelf and therefore significant portions of the glacial record are below present sea level. The availability of high resolution multibeam swath bathymetric and geophysical sub-bottom data for over 30,000 km2 of the northwest Irish continental margin (between 55 40 and 54 18 N, and 7 50 and 11 4W) has made it possible to map glacial features on the continental shelf and glacially-related features on the continental slope and rise. The resulting map, presented here at a scale of 1:260,000, shows that the major glacial features consist of subglacial bedforms and nested arcuate moraines of different orientations across the width of the shelf. Distal to these moraines, the outermost shelf and upper slope are crossed by sub-parallel and cross-cutting furrows created by iceberg scouring and meltwater discharge at the ice margin. A well-developed system of gullies and canyons and frequent escarpments incise the continental slope. Several large depositional lobes, likely related to the delivery of vast amount of sediment at the ice margin are found in inter-canyon areas and at the base of the slope. Collectively these data show an extensive ice sheet margin across the entire shelf and sedimentation on the continental margin was greatly affected by the presence of the ice margin at the shelf edge.

Glacial geomorphological mapping of Shuttle Radar Topography Mission (SRTM) data from the western Canadian Prairies demonstrates that during the last (late Wisconsinan) deglaciation of the Laurentide Ice Sheet terrestrial ice streams underwent a major reorganization of their flow configuration. This reorganization involved a 90° shift in flow direction and was accompanied by a corresponding increase in the influence of topography on streaming flow. Ice streams included both topographically confined and “pure” ice streams that flowed independent of topography. Streaming flow is recorded by suites of highly elongate (>60 km long) subglacial bedforms, bounded sharply at their lateral margins by prominent moraines. Initial streaming flow was unconfined by topography but was replaced progressively, and crosscut, by younger topographically confined flows. Flow reorganization is inferred to have been caused by temporal and spatial variations in the interaction between frozen and thawed bed conditions, with thinning and shutdown of one ice stream ultimately triggering initiation of others. This highlights the role of internal glaciodynamically driven reorganization in triggering streaming flow within large ice sheets and shows that large-scale flow reorganization can occur over the time scale of a single deglaciation in terrestrial ice streams.

Glacimarine diamicts are produced by diverse processes, and genetic differentiation is often problematic using macro-sedimentological criteria alone. Micromorphology offers a potentially helpful tool in such investigations. Macroscopically massive diamict samples of known glacimarine origin, from the Polar North Atlantic, Antarctica and north Irish Sea, were prepared for micromorphological analysis to (1) identify microstructures unique to different modes of sedimentation and (2) interpret genetic processes from those structures. The samples comprised examples of debris-flow, iceberg-turbate and suspension settling deposits from late Quaternary glacier-influenced marine environments: tidewater glacier, sub- or pro-ice shelf and continental slopes in front of ice stream termini. Results show two significant features of debris-flow sediments: a bimodal grain fabric of near-horizontal and -vertical grains, and laminated clay and silt coatings on sand and pebble grains. Coatings are best developed in sediments with finer grain-size distributions and in debris-flow sediments which have had relatively long run-out distances on trough-mouth fans, suggesting continuous rotation of grains in a buoyant, turbulent aqueous environment. This is significant because it precludes debris-flow delivery by plug flow. The micromorphology of iceberg turbate has not been described previously. It contains structures similar to those described in tills, so that unambiguous identification of these sediments seems unlikely based on micromorphological criteria alone. Suspension sediments range from fine-grained massive diamicts containing microfossils to more heterogeneous coarser sediments characterised by abrupt textural variations, from ice-distal and ice-proximal glacimarine environments respectively. The ice-proximal sediments contain fine vertical lineations marking the trajectories of dropstones through wet matrix. These dropstone tracks have not been reported in previous studies.

This research reconstructs ice-sheet processes operating during the Late Devensian in northeast England. The article assesses the lithostratigraphy of the Devensian glacial tills of Whitburn Bay, eastern County Durham, and presents the first detailed analysis of petrological, geochemical and biostratigraphical data to reconstruct lithostratigraphy, provenance and iceflow pathways. Two Devensian tractions tills (the Blackhall and Horden tills) are separated by a boulder pavement, pointing to a switch in ice-bed conditions and the production of a melt-out lag prior to deposition of the upper traction till, the Horden Till. The Blackhall Till contains Magnesian Limestone, Carboniferous Limestone, Whin Sill dolerite and Old Red Sandstone, suggesting a northwesterly source, probably from the Midland Valley and the Southern Uplands. The Horden Till contains erratics and heavy minerals derived from crystalline bedrock sources in the Cheviot Hills and northeast Scotland. Within the Horden Till are numerous sand, clay and gravel-filled canals incised downwards into the diamicton which are attributed to a low-energy, distributed, subglacial canal drainage system. Coupled with hydro-fractures and the boulder pavement, this suggests that a partially decoupled, fast-flowing ice stream deposited the Horden Till. The uphill, landward direction of ice movement indicates that the ice stream was confined in the North Sea Basin, possibly by the presence of Scandinavian Ice.

Digital elevation models of the area around the Solway Lowlands reveal complex subglacial bedform imprints relating the central sector of the LGM British and Irish Ice Sheet. Drumlin and lineation mapping in four case studies show that glacier flow directions switched significantly through time. These are summarised in four major flow phases in the region: Phase I flow was from a dominant Scottish dispersal centre, which transported Criffel granite erratics to the Eden Valley and forced Lake District ice eastwards over the Pennines at Stainmore; Phase II involved easterly flow of Lake District and Scottish ice through the Tyne Gap and Stainmore Gap with an ice divide located over the Solway Firth; Phase III was a dominant westerly flow from upland dispersal centres into the Solway lowlands and along the Solway Firth due to draw down of ice into the Irish Sea basin; Phase IV was characterised by unconstrained advance of Scottish ice across the Solway Firth. Forcing of a numerical model of ice sheet inception and decay by the Greenland ice core record facilitates an assessment of the potential for rapid ice flow directional switching during one glacial cycle. The model indicates that, after fluctuations of smaller radially flowing ice caps prior to 30 ka BP, the ice sheet grows to produce an elongate, triangular-shaped dome over NW England and SW Scotland at the LGM at 19.5 ka BP. Recession after 18.5 ka BP displays a complex pattern of significant ice flow directional switches over relatively short timescales, complementing the geomorphologically-based assessments of palaeo-ice dynamics. The palaeoglaciological implications of this combined geomorphic and modelling approach are that: (a) the central sector of the BIIS was as a major dispersal centre for only ca 2.5 ka after the LGM; (b) the ice sheet had no real steady state and comprised constantly migrating dispersal centres and ice divides; (c) subglacial streamlining of flow sets was completed over short phases of fast flow activity, with some flow reversals taking place in less than 300 years.

Swath bathymetric and sub-bottom profiler data reveal a variety of submarine landforms such as gullies, slide scars, subtle shelf edge-parallel ridges and elongated depressions, and small debris flows along the continental shelf break and upper slope of West Antarctica. Gullies cutting through debris flow deposits on the Belgica Trough Mouth Fan (TMF) suggest formation after full-glacial deposition on the continental slope. The gullies were most likely eroded by sediment-laden subglacial meltwater flows released from underneath the ice margin grounded at the shelf edge at the onset of deglaciation. Scarcity of subglacial meltwater flow features on the outer shelf suggests that the meltwater reached the shelf edge mainly either through the topmost layer of soft diamict or in the form of dispersed flow beneath the ice, although locally preserved erosional channels indicate that more focused and higher-energy flows also existed. Concentration of gullies on the upper continental slope in front of the marginal areas of the major cross-shelf troughs, as contrasted to their axial parts, is indicative of higher-energy gully-eroding processes there, possibly due to additional subglacial meltwater flow from beneath the slow moving ice lying over the higher banks of the troughs. The shallow and sinuous gully heads observed on the outermost shelf within the Pine Island West Trough may indicate postglacial modification by near-bed currents resulting either from the subglacial meltwater flow from underneath the ice margin positioned at some distance landward from the shelf edge, or from the currents formed by brine rejection during sea ice formation. On the continental slope outside major troughs, slide scars as well as shelf-edge parallel ridges and elongated depressions indicate an unstable and failure-prone uppermost slope, although failures were probably mainly associated with rapid sediment loading during glacial periods. Complex, cauliflower- and amphitheatre-shaped gully heads biting back into the shelf edge suggest upslope retrogressive, multi-stage small-scale sliding as a contributing factor to the formation of gullies in these areas. Small debris fans immediately downslope of the slide scars suggest that small-scale debris flows have been the main downslope sediment transfer processes in the areas of weak or absent subglacial meltwater flow.

High-resolution swath bathymetry and TOPAS sub-bottom profiler acoustic data from the inner and middle continental shelf of north-east Greenland record the presence of streamlined mega-scale glacial lineations and other subglacial landforms that are formed in the surface of a continuous soft sediment layer. The best-developed lineations are found in Westwind Trough, a bathymetric trough connecting Nioghalvfjerdsfjorden Gletscher and Zachariae Isstrom to the continental shelf edge. The geomorphological and stratigraphical data indicate that the Greenland Ice Sheet covered the inner-middle shelf in north-east Greenland during the most recent ice advance of the Late Weichselian glaciation. Earlier sedimentological and chronological studies indicated that the last major delivery of glacigenic sediment to the shelf and Fram Strait was prior to the Holocene during Marine Isotope Stage 2, supporting our assertion that the subglacial landforms and ice sheet expansion in north-east Greenland occurred during the Late Weichselian. Glacimarine sediment gravity flow deposits found on the north-east Greenland continental slope imply that the ice sheet extended beyond the middle continental shelf, and supplied subglacial sediment direct to the shelf edge with subsequent remobilisation downslope. These marine geophysical data indicate that the flow of the Late Weichselian Greenland Ice Sheet through Westwind Trough was in the form of a fast-flowing palaeo-ice stream, and that it provides the first direct geomorphological evidence for the former presence of ice streams on the Greenland continental shelf. The presence of streamlined subglacially derived landforms and till layers on the shallow AWI Bank and Northwind Shoal indicates that ice sheet flow was not only channelled through the cross-shelf bathymetric troughs but also occurred across the shallow intra-trough regions of north-east Greenland. Collectively these data record for the first time that ice streams were an important glacio-dynamic feature that drained interior basins of the Late Weichselian Greenland Ice Sheet across the adjacent continental margin, and that the ice sheet was far more extensive in north-east Greenland during the Last Glacial Maximum than the previous terrestrial-glacial reconstructions showed.

The Antarctic Peninsula is one of the three fastest warming regions on Earth. Here we review Holocene proxy records of marine and terrestrial palaeoclimate in the region, and discuss possible forcing mechanisms underlying past change, with a specific focus on past warm periods. Our aim is to critically evaluate the mechanisms by which palaeoclimate changes might have occurred, in order to provide a longer-term context for assessing the drivers of recent warming. Two warm events are well recorded in the Holocene palaeoclimate record, namely the early Holocene warm period, and the `Mid Holocene Hypsithermal' (MHH), whereas there are fewer proxy data for the `Mediaeval Warm Period' (MWP) and the `Recent Rapid Regional' (RRR) warming. We show that the early Holocene warm period and MHH might be explained by relatively abrupt shifts in position of the Southern Westerlies, superimposed on slower solar insolation changes. A key finding of our synthesis is that the marine and terrestrial records in the AP appear to show markedly different behaviour during the MHH. This might be partly explained by contrasts in the seasonal insolation forcing between these records. Circumpolar Deep Water (CDW) has been implicated in several of the prominent changes through the Holocene but there are still differences in interpretation of the proxy record that make its influence difficult to assess. Further work is required to investigate contrasts between marine and terrestrial proxy records, east—west contrasts in palaeoclimate, the history of CDW, to retrieve a long onshore high resolution record of the Holocene, and determine the role of sea ice in driving or modulating palaeoclimate change, along with further efforts to study the proxy record of the RRR and the MWP.

The Easington Raised Beach, in Shippersea Bay, County Durham, is the most northerly known interglacial beach deposit in England. It lies directly on Magnesian Limestone bedrock at 33 m O.D. and is covered by glacial sediments attributed to the Devensian. Detailed sedimentological analysis suggests that it is an interglacial beach, which is supported by the presence of pebbles bored by marine organisms and littoral, temperate-climate, marine macro- and micro-fossils. It comprises beds of unconsolidated, bedded, imbricated, well-rounded sands and gravels, overlain by similar, but calcreted, deposits. The gravel fraction is dominated by Magnesian and Carboniferous limestone, with orthoquartzite, flint, and porphyries also present; these are far-travelled erratics that must have derived from the erosion of older glacially transported sediments. Previous workers have described erratics derived from the Oslofjord region of Norway in the raised beach gravel, although rocks diagnostic of a Scandinavian origin have not been recovered as part of this study. The heavy-mineral suite is rich in epidote, dolomite, clinopyroxenes, garnet, tourmaline, and micas. The beach was dated previously by conventional amino acid analysis of the shells, which suggested a Marine Isotope Stage (MIS) 7 age, albeit with a reworked component from MIS 9. This has been confirmed by new optically stimulated luminescence (OSL) dates, which indicate that the beach formed between 240 and 200 ka BP. New amino acid racemisation analyses, using a modified technique, broadly support this interpretation but must await more comparative data before they can be assessed fully. The strong indication of an MIS 7 age for the formation of the beach has implications for the uplift history of northeastern England during the Pleistocene, and indicates an uplift rate of 0.19 mm a −1 . The stable isotope geochemistry indicates that the cementation occurred during an interglacial period, whilst U-Series dating of the cement indicates that cementation occurred mostly during the Holocene, and is genetically related to the overlying Devensian till. This work has formed part of a full re-appraisal of the glacial sequence in eastern County Durham, the results of which suggest that the Warren House Formation pre-dates the raised beach, and that the Devensian Horden Till overlies the raised beach.

A 330-km length of the little known continental shelf edge and slope of the Bellingshausen Sea, West Antarctica, is investigated using multibeam swath-bathymetric and sub-bottom profiler evidence. The shelf break is at 650-700 m across the 150-km wide Belgica Trough, and to either side is about 500 m. When full-glacial ice advanced across the shelf to reach the shelf break, it was partitioned into fast- and slow-flowing elements, with an ice stream filling the trough. This had important consequences for the nature and rate of sediment delivery to the adjacent continental slope. Off Belgica Trough, the upper continental slope has convex-outward contours indicating a major sedimentary depocentre of gradient 1-2 degrees. Acoustic profiles and cores from the depocentre show a series of diamictic glacigenic debris flows. The depocentre is interpreted as a trough-mouth fan, built largely by debris delivered from the ice stream. The slope is steeper beyond the trough margins at up to 6 degrees. The main morphological features on the Bellingshausen Sea slope are gully systems and channels. Major canyons and Late Quaternary slides are absent. Most gullies and channels are found on the fan. Gullies are about 15-25 m deep, a few hundred metres wide and some are >25 km long. The largest channel is over 60 km long, about a kilometre wide and 10 to 15 m deep. The channels provide pathways for sediment by-passing of the upper slope and transfer to the continental rise and beyond by turbidity currents. Gullies on the Bellingshausen Sea margin cut through debris flows on the slope. Assuming the debris flows are linked mainly to downslope transport of diamictic debris when ice was at the shelf edge under full-glacial conditions, then those gullies cut into them formed during deglaciation. Belgica Fan is >22,000 km(2) in area and about 60,000 km(3) in volume. It is the largest depocentre identified to date on the continental margin of the West Antarctic Ice Sheet, fed by an interior ice-sheet basin of approximately 200,000 km(2). (C) 2008 Elsevier B.V. All rights reserved.

We here present a glacial geomorphological map covering 11,800km2\ud , at a scale of \ud 1:550,000, of the central sector of the last (Main Late Devensian) British-Irish Ice \ud Sheet. The map is based on the 5m resolution NEXTMap dataset. Six landform types \ud have been mapped; subglacial lineations, hummocky terrain, ribbed moraine, \ud meltwater channels, eskers and glaciofluvial sediment accumulations. The subglacial \ud lineations have been further sub-divided into a series of ‘flow sets’ based on their \ud morphology, conformity and length. Over 9,000 individual landforms have been \ud identified within the study area, concentrated predominantly in the lowlands of the \ud Vale of Eden, Solway and over the Tyne and Stainmore Gaps. A palimpsest \ud geomorphic signature characterised by cross-cutting flow-sets is interpreted as \ud evidence that dynamic, multiphase ice flow occurred throughout the Main Late \ud Devensian (marine isotope stage 2) in response to migrating ice dispersal centres and \ud ice divides. A relative chronology has been constructed and interpreted, based on the \ud complex, cross-cutting flow signatures displayed throughout the region. \ud

Submarine landforms preserved in bathymetric troughs on the Antarctic continental shelf show that the style of ice stream retreat across the shelf following the last glacial maximum varied between different troughs. Three styles of retreat are inferred from the geological evidence: rapid, episodic and slow. Rapid retreat by ice stream floatation and calving is recorded by the preservation of a landform assemblage of unmodified streamlined subglacial bedforms including mega-scale glacial lineations (MSGLs) that record streaming flow along these troughs. These elongate bedforms are not overprinted by recessional glacial landforms formed transverse to ice flow such as moraines or grounding-zone wedges, and overlying deglacial sediments are thin. A second type of landform assemblage consists of MSGLs overprinted or interrupted by transverse grounding-zone wedges. This assemblage implies episodic retreat between successive grounding-zone positions. The third type of landform assemblage is that of numerous, closely spaced, recessional moraines and intermittent grounding-zone wedges that overlie and interrupt MSGLs. This assemblage records the slow retreat of grounded ice across the shelf. Variation in the style of ice stream retreat between the different bathymetric troughs indicates that Antarctic palaeo-ice-streams did not respond uniformly to external forcing at the end of the last glacial cycle. Rather, their diachronous retreat reflects the dominance of local controls in the form of bathymetry and drainage basin size. More broadly, these data show that retreat of marine-based ice sheets in areas of reverse bed slope is not necessarily catastrophic, and they provide important constraints for numerical models that attempt to predict the dynamics of large polar ice sheets. Copyright © 2008 John Wiley & Sons, Ltd.

Investigation of Late Quaternary glacigenic sediments exposed in coastal sections on the Dingle Peninsula, southwest Ireland shows that during the last glaciation, an advance of local ice occurred across the western and northern coasts of the peninsula and deposited a series of subglacial tills. These tills were formed largely by the subglacial reworking of underlying parent material. Sedimentological contrasts between them reflect variations in the nature of the parent material from which the tills were derived, as well as variations in the magnitude of strain during till formation. The local ice reworked pre-existing glacial deposits associated with an earlier advance of regional ice from the north. Evidence for this earlier advance of regional ice is provided by erratics of Galway Granite contained within the tills at some sites. No in-situ deposits associated with the granite-carrying ice were observed on the peninsula. Clast macrofabric and provenance data indicate that all of the tills recorded are the product of the radial flow of local ice coastwards from the peninsula.

The sedimentology and structural features of the Bannow Till are presented from two sites in Bannow Bay, County Wexford, southern Ireland, the stratotype for this Irish inland till. Beach deposits of last interglacial age are overlain locally by aeolian sands, providing a maximum age for the deposition of the Bannow Till. Three sedimentary units at Bannow comprise a vertical continuum of sheared bedrock (glacitectonite) grading upwards into a subglacial till of mostly local derivation. Shearing and clast macrofabric data indicate that ice flow was from the north to northeast, indicative of glacier movement from an inland source. At Wood Village, glacier advance from the northeast is recorded by the glacitectonization of bedrock, interglacial marine sands, aeolian sands and periglacial slope deposits. This glacitectonized sequence of sediments is overlain unconformably by an extensive tabular unit of interbedded diamictons and stratified sediments typical of deposition in proximal proglacial outwash fans. The Bannow Till is classified as a glacitectonite-subglacial traction till continuum, having been derived from the shearing and fragmentation of shale bedrock from which blocks and slabs have been displaced along fault planes by brittle deformation and then edge-rounded and pulverized. The stratigraphic nature of the evidence for glaciation at Bannow Bay, and hence the Bannow Till stratotype, is typical of glacier/ice-sheet marginal settings in areas of soft bedrock.

Reconstructions of the British–Irish Ice Sheet (BIIS) during the Last Glacial Maximum (LGM) in the Celtic Sea and southern Ireland have been hampered by a paucity of well-dated stratigraphic records. As a result, the timing of the last advance of the largest outlet of the BIIS, the Irish Sea Ice Stream, to its maximum limit in the Celtic Sea has been variously proposed as being pre-last glaciation, Early Devensian and LGM. The Irish Sea Till was deposited by the Irish Sea Ice Stream during its last advance into the Celtic Sea. We present 26, stratigraphically well constrained, new AMS radiocarbon dates on glacially transported marine shells from the Irish Sea Till in southern Ireland, which constrain the maximum age of this advance. The youngest of these dates indicate that the BIIS advanced to its overall maximum limit in the Celtic Sea after 26,000–20,000 14C yr BP, thus during the last glaciation. The most extensive phase of BIIS growth therefore appears to have occurred during the LGM, at least along the Celtic Sea and Irish margins. These data further demonstrate that the uppermost inland glacial tills, from the area of supposed “older drift” in southern Ireland, a region previously regarded as having been unglaciated during the LGM also date from the last glaciation. Thus most of southern Ireland was ice covered at the LGM. Advance of the BIIS to its maximum southern limit in the Celtic Sea may have been a short-lived glaciodynamic response facilitated by subglacial bed conditions, rather than a steady-state response to climate forcing alone.

High-resolution swath-bathymetry data from inner Kongsfjorden, Svalbard, reveal characteristic landform assemblages formed during and after surges of tidewater glaciers, and provide new insights into the dynamics of surging glaciers. Glacier front oscillations and overriding related to surge activity lead to the formation of overridden moraines, glacial lineations of two types, terminal moraines, associated debris lobes and De Geer moraines. In contrast to submarine landform assemblages from other Svalbard fjords, the occurrence of two kinds of glacial lineations and the presence of De Geer moraines suggest variability in the landforms produced by surge-type tidewater glaciers. All the landforms in inner Kongsfjorden were deposited during the last c. 150 years. Lithological and acoustic data from the innermost fjord reveal that suspension settling from meltwater plumes as well as ice rafting are dominant sedimentary processes in the fjord, leading to the deposition of stratified glacimarine muds with variable numbers of clasts. Reworking of sediments by glacier surging results in the deposition of sediment lobes containing massive glacimarine muds. Two sediment cores reveal minimum sediment accumulation rates related to the Kongsvegen surge from 1948; these were 30 cm a-1 approximately 2.5 km beyond the glacier front shortly after surge termination, and rapidly dropped to an average rate of 1.8 cm a-1 in ∼1950, during glacier retreat. Grant IP2010040970 from the Polish Ministry of Science and Higher Education; Grant 2013/10/E/ST10/00166 from the Polish National Science Center; PetroMaks project “Glaciations in the Barents Sea area (GlaciBar)”, was funded by the Research Council of Norway (RCN), Statoil, Det Norske oljeselskap ASA and BG group Norway (Grant 200672); Centre of Excellence “Arctic Gas Hydrate, Environment and Climate (CAGE)” at the Department of Geology, UiT-The Arctic University of Norway funded by RCN (Grant 223259); European Commission FP7-People 2012—Initial Training Networks “Glaciated North Atlantic Margins (GLANAM)”

Previous reconstructions of the British–Irish Ice Sheet (BIIS) envisage ice streaming from the Irish Sea to the Celtic Sea at the Last Glacial Maximum, to a limit on the mid-shelf of the Irish-UK sectors. We present evidence from sediment cores and geophysical profiles that the BIIS extended 150 km farther seaward to reach the continental shelf edge. Three cores recently acquired from the flank of outer Cockburn Bank, a shelf-crossing sediment ridge, terminated in an eroded glacigenic layer including two facies: overconsolidated stratified diamicts; and finely-bedded muddy sand containing micro- and macrofossil species of cold water affinities. We interpret these facies to result from subglacial deformation and glacimarine deposition from turbid meltwater plumes. A date of 24,265 ± 195 cal BP on a chipped but unabraded mollusc valve in the glacimarine sediments indicates withdrawal of a tidewater ice sheet margin from the shelf edge by this time, consistent with evidence from deep-sea cores for ice-rafted debris peaks of Celtic Sea provenance between 25.5 and 23.4 ka BP. Together with terrestrial evidence, this supports rapid (ca 2 ka) purging of the BIIS by an ice stream that advanced from the Irish Sea to the shelf edge and collapsed back during Heinrich event 2.