Englacial kames near Jeziorany (Warmia — western Masurian Lakeland,Poland): Morphology,internal structure and origin

Groups of hills on a regional Vistulian (Weichselian) deglaciation plateau (Warmia, NE Poland) are covered by till of up to a dozen metres thick. It is the same till of the main stadial of the Vistulian glaciation that outcrops in the upland. The internal parts of the hills consist of fine-grained sands. These glacial landforms are referred to as englacial kames; they result from infilling of englacial caverns with sand. The orientation of the kame fields and the form pattern within these fields coincide with the system of primary crevasses in the ice, as it was reconstructed on the basis of the orientation of postglacial crevasse forms. The origin of the englacial caverns at crossing points of crevasse surfaces in the glacier is discussed. Structural analysis (relationship with a circular lineament, local differentiation of the complete profile of the Pleistocene deposits, possibility of occurrence of faults — festoon glacitectonics) suggests that the origin of these landforms is related to movements in the substratum.     

Structure and rhythmic pattern of glaciofluvial deposits north of Lake Vänern, south-central Sweden

The glaciofluvial deposits of the Vanern plain, Värmland, form esker systems and trains. Esker trains are defined as series of short eskers, kames and other glaciofluvial deposits. Trains spreading fanlike from the same area are combined into esker systems. Some individual deposits are described. The general pattern differs from the long, coherent eskers typical of eastern Sweden. A rhythmic pattern of depositional units in the esker trains is found to correspond to a 10 to 11 yr cycle, possibly representing the sunspot cycle. Zones of alternating faster and slower retreat of the ice margin are identified. Two lines of slower retreat, the Karlstad and Fryken lines, correspond to the Norwegian Ski line, dated at 10 000 BP (conventional radiocarbon years) and to a slightly younger line. The spacing of the esker trains is controlled by topography in the north, but by basal ice melting, which controlled their flow and spacing on the Ratter terrain in the south.     

Deglaciation pattern indicated by the ice-margin formations in Northern Karelia, eastern Finland

A map has been reconstructed representing the large-scale glacial and glaciofluvial morphology of Northern Karelia and the adjacent area of Soviet Karelia. Observations have been made on the directions of glacial striae and on the distribution of sub-aquatic and supra-aquatic terrain in order to obtain a consistent picture of the course of deglaciation in the area and the factors affecting it. The map indicates that the behaviour of the glacier during the deglaciation was largely governed by the distribution of sub-aquatic and supra-aquatic areas. The marginal zone of the ice sheet was divided into two large lobes in this area. The Finnish Lake District Lobe terminated mostly in water, giving rise to massive glaciofluvial accumulations, while the North Karelian Lobe flowed on the land above the highest shore levels, pushing up several more or less discontinuous narrow end-moraine ridges. Relatively large glaciofluvial deposits were also formed in the supra-aquatic area in places where the ice margin terminated in a local ice-dammed lake. It is evident that the Salpausselkä I and II end-moraines extend as continuous formations only to the zone where the former ice margin rose onto dry land during the deglaciation phase. The spatial and temporal differences in the glacial dynamics and differing depositional environments gave rise to the complex glacial morphology of Northern Karelia.     

The Brampton kame belt and Pennine escarpment meltwater channel system (Cumbria, UK): Morphology, sedimentology and formation

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.     

Stratigraphy and sedimentology of Devensian (Dimlington Stadial) glacial deposits,east Yorkshire,England

The stratigraphy and sedimentology of the glacial deposits exposed along the coast of east Yorkshire are reviewed. Critical sections at Filey Brigg, Barmston and Skipsea are examined to reassess the stratigraphy of Devensian Dimlington Stadial glacial deposits in the light of recent developments in glacial sedimentology. Sedimentary and glaciotectonic structures studied in the field and by using scanning electron microscopy are emphasised. Two hypotheses are considered for the genesis of the interbedded diamictons and stratified sediments. The first involves the deposition of lodgement till and/or deformation till followed by meltout till, which was overridden to produce more deformation till, reflecting periods of ice stagnation punctuated by glacier thickening. The second hypothesis, which is favoured on the basis of field evidence and micromorphology, involves the vertical accretion of a deforming till layer associated with cavity/channel or tunnel valley fills, beneath active ice. At Barmston the upper part of the diamicton contains elongate pendant structures containing gravels, indicating that the diamicton was saturated and able to flow. The diamictons, therefore, represent a complex sequence of tills deposited and deformed by active ice during the Dimlington Stadial. Previously published stratigraphical schemes involving classifications of multiple tills in east Yorkshire should be simplified and it is more appropriate to assign these to a single formation, the Skipsea Till Formation. Rhythmic glaciolacustrine and proglacial glaciofluvial sediments overlie the tills at Barmston and Skipsea. These were deposited in sag basins during deglaciation as the tills settled and deformed under thickening sediment and as buried ice melted out. Extensive sands and gravels cap the succession and were deposited on a sandur during the later stages of deglaciation.     

Meltwater phenomena in the area between bala and corwen,North Wales

Previously unrecorded glacio-fluvial phenomena are identified and mapped. These are shown to conform in part with the known southwest to northeast movement of meltwater from the wasting ‘Merioneth’ icecap in late Devensian time. A further series of meltwater channels and associated kames is also revealed, connecting southwards with the Dee Valley. Orientation of bedding within these latter kame deposits at Sarnau (971394) is also shown to accord with deposition by meltwater from an ice front to the southwest. Petrological analysis of igneous erratics within the Sarnau deposits suggests an origin entirely within the Arenig Mountains. It is thus postulated that the features relate to a late stage in the wasting of the 'Merioneth' ice cap, when a series of meltwater escape routes to the Dee Valley became progressively ice-free, and that the newly-discovered meltwater channel system is thus complementary to previously recorded phenomena.     

The Late Devensian and Flandrian history of the Teith valley, Scotland

Two episodes of glaciation are identified in the Teith valley, central Scotland. During the earlier episode, the valley was wholly occupied by an ice sheet, but during the later episode, correlated with the Loch Lomond Readvance, ice only occupied the upper part of the valley. The deglaciation which followed each episode was marked in particular by sequences of kame and outwash terraces. A terrace related to the second episode grades into a large fan buried beneath a sequence of marine deposits in the nearby Forth valley. The latest of these, the carse clays, are related to Flandrian terraces in the Teith valley.     

Meltwater phenomena in the area between Bala and Corwen,North Wales

Previously unrecorded glacio-fluvial phenomena are identified and mapped. These are shown to conform in part with the known southwest to northeast movement of meltwater from the wasting ‘Merioneth’ icecap in late Devensian time. A further series of meltwater channels and associated kames is also revealed, connecting southwards with the Dee Valley. Orientation of bedding within these latter kame deposits at Sarnau (971394) is also shown to accord with deposition by meltwater from an ice front to the southwest. Petrological analysis of igneous erratics within the Sarnau deposits suggests an origin entirely within the Arenig Mountains. It is thus postulated that the features relate to a late stage in the wasting of the ‘Merioneth’ ice cap, when a series of meltwater escape routes to the Dee Valley became progressively ice-free, and that the newly-discovered meltwater channel system is thus complementary to previously recorded phenomena.     

Deglaciation models from the Swedish West Coast

Deglaciation processes within different rock relief types are discussed. The lower parts of the fissure-valley landscape in western Sweden were covered by the late-glacial sea at deglaciation, while the rock plateaux between the valleys formed an arctic archipelago. The glacial movements, deposition activity and recession were intimately dependent on the variations of the topography and on the buoyancy of the seawater in the valleys. The opinion that a piedmont glaciation existed in eastern Halland during the deglaciation stage has been corroborated concerning areas above the marine limit. In the valleys below this limit the ice margin, however, was straight or slightly concave. The western part of the South Swedish Highland, situated high above the marine limit, is characterized by a zonal deglaciation; zone by zone of the ice margin was detached from the actively moving ice and became immobile. Subglacially formed eskers appear together with glaciofluvial deltas which formed extramarginally in ice-dammed lakes. The moraine forms are often dominated by 1–2 km long drumlins with rock cores. Where the ice diverged over a convex bedrock basement, Rogen-like moraine ridges, radial as well as transverse, were formed during the deglaciation stage when the ice was stagnating.     

Distribution and genesis of tills in central south Norway

The morphogenesis of tills below the culmination zones of the Weichsclian inland ice has been studied an an upland area with a relief of 1500 m. The thickness of the tills varies considerably, depending principally on gee-morphology, ice-movement directions, and glaciofluvial drainage during the last deglaciation period. The thickest tills, found in valleys, accumulated in three ways. Glaciofluvial/lacustrine sediments of prcsumed Mid-Weichselian age have been discovered beneath the tills at niorc than 10 localities. The overlying tills are correlated with different phases of ice movement reconstructed on the basis of detailed studies of stt-iae. The till stratigraphy of one locality, Stenseng, is described in detail. Based upon combined analyses of texture, structure, and fabric, four different hasal tills are recognized, each corresponding to a particular ice direction. A characteristic boulder layer represents a change in thc direction of glacial movement. Boulder layers in till are thought to he essential for the development of earth pillars.     

Glacial deposits and Late Weichselian ice-sheet dynamics in the northeastern Baltic Sea

Glacial deposits and landforms, interpreted from the continuous seismic reflection data, have been used to reconstruct the Late Weichselian ice-sheet dynamics and the sedimentary environments in the northeastern Baltic Sea. The bedrock geology and topography played an important role in the glacial dynamics and subglacial meltwater drainage in the area. Drumlins suggest a south-southeasterly flow direction of the last ice sheet on the Ordovician Plateau. Eskers demonstrate that subglacial meltwater flow was focused mostly within bedrock valleys. The eskers have locally been overlain by a thin layer of till. Thick proximal outwash deposits occupy elongated depressions in the substratum, which often occur along the sides of esker ridges. Ice-marginal grounding-line deposit in the southern part of the area has a continuation on the adjacent Island of Saaremaa. Therefore, we assume that its formation took place during Palivere Stadial of the last deglaciation, whereas the moraine bank extending southwestward from the Serve Peninsula is tentatively correlated with the Pandivere Stadial. The wedge-shaped ice-marginal grounding-line deposit was locally fed by subglacial meltwater streams during a standstill or slight readvance of the ice margin. The thickness of the glacier at the grounding-line was estimated to reach approximately 180 m. In the western part of the area, terrace-like morphology of the ice-marginal deposit and series of small retreat moraines 10–20 km north of it suggest stepwise retreat of the ice margin. Therefore, a rather thin and mobile ice stream was probably covering the northeastern Baltic Sea during the last deglaciation.     

Formation of De Geer moraines and implications for deglaciation dynamics

De Geer moraines are very common in the Møre area, western Norway. These moraines occur below the marine limit and outside the Younger Dryas ice limit and occupy tributaries that connect the main fjords through the mountain passes. During deglaciation, ice in these tributaries flowed to the major ice streams. Sections across three De Geer moraines show that the ridges are composed of diamictons and fine-grained sediment, partly in stacked sequences. The diamicton units are interpreted as being composed of water-lain tills, lodgements tills and subaqueous flow deposits. The fine-grained sediment is though to have formed in a proglacial marine environment. Clast fabric of diamictons and deformation structures in underlying sands show that depositional directions for diamicton units and the direction of deformation for the sands is perpendicular to the ridge crests. Mainly based on this evidence, the ridges are thought to have formed by push at the glacier grounding line. The formation of transverse ridges (relative to ice flow) do occur in basal crevasses on modern glaciers, as do swarms of ridges along the front of retreating glaciers. The first mechanism of deposition does not seem to explain the ridges studied in the present paper and hence the importance of this process in the formation of De Geer moraines is questioned. The De Geer moraines were deposited by ice lobes advancing from one main fjord into another; therefore by studying the drainage pattern of the tributary lobes and their sequence of deglaciation, many features of the style of deglaciation of the ice sheet across the area can be determined. The northwestern part of the area was deglaciated earliest. After that, deglaciation proceeded to the southwest parallel to the coast. Subsequently the outer and the central part of Romsdalsfjorden were deglaciated causing ice to drain towards this fjord from both the north and south. The last fjord to be deglaciated was Storfjorden in the south.     

Glacial dynamics and transport of debris during the final phases of the Weichselian Glaciation,southwest Skåne,Sweden

Late Weichselian glacial sediments were studied in three sections west of Lund, southwest Sweden. The lowermost sedimentary unit is a lodgement till containing rock fragments derived from the northeast-east. Fabric analyses indicate successive ice flow directions: from the northeast, east-northeast, south-southeast and then east. The last active ice movement in the area was from the east. Above the lodgement till are deglaciation sediments consisting of meltout till, flow till and glaciofluvial sand and gravel deposited in a subaerial stagnant-ice environment. The uppermost unit consists of glaciolacustrine clay and silt, containing abundant ice-rafted debris, deposited during a short-lived transgression phase when stagnant ice was still present in the area. At the westernmost site investigated, the petrographical composition of the deglaciation deposits displays a gradual change, with upwards increasing components of Cretaceous chalky limestone. The presence of this rock type requires a period of glacial transport from the south. This stratigraphy cannot be explained with traditional glaciodynamic models. A possible scenario can, however, be constructed using a previously published model (Lagerlund, 1987) where marginal ice domes in the southwestern Baltic area interact with the main Scandinavian Ice Sheet.     

The Quaternary geology of the British Isles

This editorial accompanies the second of two sets of papers in the Proceedings (the first set appeared in Part 4 of 2009) that arise from the Annual Discussion Meeting of the Quaternary Research Association, co-hosted by the Royal Geographical Society. This collection represents two main categories of paper: on (1) on sand and gravel, several arising from projects funded from the British Government's Aggregates Levy, and (2) glaciation, with a degree of overlap between these. Both categories also include results of PhD research. The first category includes presentation of fluvially-based data from SW England, North Yorkshire, the Trent and the Fen Basin, as well as studies of raised beach deposits in southern England and County Durham. At the boundary between the categories is a paper on a pre-glacial fluvial valley system in the glaciated Dyfi basin, west Wales, and another on the marginal area between the Late Devensian Welsh ice cap and the contemporaneous Irish Sea ice stream, encompassing glacio-fluvial sands and gravels as well as fully glacigenic diamictons. There are also papers on the Woore Moraine, in Shropshire, and the glaciofluvial deposits of the Brampton kame belt, east of Carlisle, Cumbria. Studies at either end of Yorkshire include a paper on the sedimentology and luminescence dating of Glacial Lake Humber deposits, in the central Vale of York, and another that documents deglaciation and the emergence of the rivers in the watershed area between the rivers of this Vale (the Swale-Ure-Ouse system) and the Tees, to the north. The latter is followed up by a third paper on the palaeo-environmental evidence from the middle ‘piedmont’ reaches of these rivers. Two final papers fall outside of these categories. One documents periglacial activity during the Loch Lomond Stadial in south London, revealing significant complexity. The second reviews the engagement of the Quaternary community with the formal education system, with institutions, policy makers, planners and with the public at large, offering examples of good practice and setting out aspirations for continuation of such ‘outreach’ in the future.     

Time-transgressive deposits of repeated depositional sequences within interlobate glaciofluvial (esker) sediments in Köyliö, SW Finland

ABSTRACT Evidence of conspicuous repeated seasonal to annual deposition of glaciofluvial and glaciolacustrine sequences within a structurally complex interlobate esker segment in SW Finland is presented. The time‐transgressive, overlapping depositional sequences consist of deposits from two successive melt seasons, including three vertically stacked lithofacies associations: (1) massive to stratified coarse gravels = summer deposits; (2) trough and ripple cross‐stratified fine‐grained deposits = autumn to winter deposits; and (3) sandy stratified beds = spring deposits. The depositional environment of each lithofacies association involves a transition from subglacial or submarginal tunnel to a subaqueous re‐entrant environment, which then passes to a proglacial glaciolacustrine environment. The study also presents evidence of headward extension of subglacial tunnel deposits, related to the rapid shifting of a tunnel expansion point during the increasing spring discharge, which occupied the old tunnel exit: this mode of annual deposition has not been reported previously in esker studies. The good preservation of the rhythmic lithofacies associations is suggested as resulting from interlobate depositional conditions associated with rapidly decaying icestreams. Therefore, the depositional model may provide a key to recognizing time‐transgressive interlobate eskers that form an important geomorphological and sedimentological record of meltwater activity during the last deglaciation of the Fennoscandian and Laurentide ice sheets. The identification of time‐transgressive interlobate eskers and associated palaeo‐icestream behaviour is an essential step forward for more accurate models of ice sheet behaviour and palaeoclimatic reconstructions.     

Late Glacial De Geer moraines with glaciofluvial sediment in the Chapais area, Québec (Canada)

Glaciofluvial De Geer moraines have rarely been described in detail in the literature. This study presents a model for the genesis of moraines of this type in the Chapais area, Québec. The model is based mainly on facies and deformatin structures analysis, and geomorphological data. Well-stratified glaciofluvial material is commonly found in the core of the moraines, whereas till or glacial diamicton may be present as surficial cover on their proximal side or as injected lenses in the sorted sediments. The paleocurrents are systematically directd downglacier. The moraines were built up in subglacial crevasses in areas where meltwater was channelized. Water flowed under pressure from small upglacier cavities, carrying a load of coars-grained material When flowing water entered crevasses already occupied by water, flow sparation occurred, reducing the capacity of the flow to carry the particles, and avalanching glaciofluvial material on the leeside of the piled sediments. The occurrence, in these sediments, of glaciotectonic deformation structures such as overturned to recumbent folds and thrust faults is evidence that the glacier was still active to some degree during and after the sedimentation phase.     

Loess sedimentation in Tibet: provenance,processes, and link with Quaternary glaciations

Well-preserved loess deposits are found on the foothills of mountains along the middle reaches of the Yarlung Zangbo River in southern Tibet. Optically stimulated luminescence (OSL) dating is used to determine loess ages by applying the single-aliquot regeneration technique. Geochemical, mineralogical, and granulometric measurements were carried out to allow a comparison between loess from Tibet and the Chinese Loess Plateau. Our results demonstrate that (i) the loess deposits have a basal age of 13–11 ka, suggesting they accumulated after the last deglaciation, (ii) loess in southern Tibet has a “glacial” origin, resulting from eolian sorting of glaciofluvial outwash deposits from braided river channels or alluvial fans by local near-surface winds, and (iii) the present loess in the interior of Tibet has accumulated since the last deglaciation when increased monsoonal circulation provided an increased vegetation cover that was sufficient for trapping eolian silt. The lack of full-glacial loess is either due to minimal vegetation cover or possibly due to the erosion of loess as glaciofluvial outwash during the beginning of each interglacial. Such processes would have been repeated during each glacial–interglacial cycle of the Quaternary.     

Sedimentary facies and landform genesis at a temperate outlet glacier: Soler Glacier, North Patagonian Icefield

This paper focuses on the structural glaciology, dynamics, debris transport paths and sedimentology of the forefield of Soler Glacier, a temperate outlet glacier of the North Patagonian Icefield in southern Chile. The glacier is fed by an icefall from the icefield and by snow and ice avalanches from surrounding mountain slopes. The dominant structures in the glacier are ogives, crevasses and crevasse traces. Thrusts and recumbent folds are developed where the glacier encounters a reverse slope, elevating basal and englacial material to the ice surface. Other debris sources for the glacier include avalanche and rockfall material, some of which is ingested in marginal crevasses. Debris incorporated in the ice and on its surface controls both the distribution of sedimentary facies on the forefield and moraine ridge morphology. Lithofacies in moraine ridges on the glacier forefield include large isolated boulders, diamictons, gravel, sand and fine-grained facies. In relative abundance terms, the dominant lithofacies and their interpretation are sandy boulder gravel (ice-marginal), sandy gravel (glaciofluvial), angular gravel (supraglacial) and diamicton (basal glacial). Proglacial water bodies are currently developing between the receding glacier and its frontal and lateral moraines. The presence of folded sand and laminites in moraine ridges in front of the glacier suggests that, during a previous advance, Soler Glacier over-rode a former proglacial lake, reworking lacustrine deposits. Post-depositional modification of the landform/sediment assemblage includes melting of the ice-core beneath the sediment cover, redistribution of finer material across the proglacial area by aeolian processes and fluvial reworking. Overall, the preservation potential of this landform/sediment assemblage is high on the centennial to millennial timescale.     

The ice lobes of the Scandinavian ice sheet during the deglaciation in Finland.

On the basis of glacial landforms interpreted by means of Landsat satellite imagery and ice-flow data obtained by other methods, the Scandinavian ice sheet has been observed to have divided at the deglaciation stage into several ice lobes. The ice lobes were more active parts of the uniform ice sheet. They represent parts that had bordered on each other in different directions or on more passive portions of the ice. The reasons for the appearance of separate ice lobes were evidently the Fennoscandian topography, the location of accumulation areas, and regional differences in the amounts of ice generated. In the boundary zones of the different ice lobes, there occur exceptionally large glaciofluvial forms and moraines (interlobate complexes). An area of passive ice was often between ice lobes, and in such areas there occur no noteworthy eskers, marginal formations or streamlined forms. In the part of Finland located on the southern side of the Arctic Circle, six different ice lobes and four major areas of passive ice are interpreted to have existed.