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In ice-cored landform assemblages, the process of resedimentation via sediment-flow is important in determining the morphology and sedimentary facies distribution after the ice core has melted. This paper documents the sediment-flow processes associated with the resedimentation of an ice-cored lateral moraine at Kongsvegen, Svalbard. Decay of the ice-cored lateral moraine is dominated by the development of a sediment-flow fan, which has an ‘hour-glass’ form in plan. The fan comprises a broad source area on the crest of the lateral moraine separated from the fan surface, composed of tessellated flow lobes, by a narrow ice-floored channel system. The principle sedimentary facies associated with this fan include matrix-supported diamictons, laminated silts and fine sands. The evolution of this fan and the likely end-products after complete deglaciation are discussed, and this paper contributes modern analogue data relevant to the interpretation of the Pleistocene landform and sediment record.

A range of subsidence structures associated with desiccation-crack piping are described from the drained proglacial lake bed of Hagavatn, Iceland. Subsurface drainage along desiccation cracks leads to the formation of small-scale subsidence structures. These subsidence structures include linear fissures, located along the limbs of desiccation cracks, and crater-like depressions that form at crack intersections. The controls on subsurface piping are discussed and the role of these subsidence structures in determining the pattern of surface drainage on the former lake bed is identified. Preservation potential of these sedimentary structure is considered to be high, given renewed lacustrine sedimentation. The potential for similar structures to be found in the geological record is considered likely, and consequently these structures may be of importance in the interpretation of crack networks in the geological record as being of subaerial as opposed to subaqueous origin.

Landform–sediment assemblages associated with two ice-dammed lakes, one active and one fossil, at Heinabergsjokull in southeast Iceland are described. The current ice-dammed lake (Vatnsdalur) is dominated by a large aggradational terrace, as well as an excellent suite of shorelines. The second fossil ice-dammed lake dates from the Neoglacial maximum of Heinabergsjokull (c. 1887) and drained during the late 1920s. This lake is associated with a suite of shorelines and ice-marginal glaciolacustrine fans. The sedimentology of one of these fans is described. Between 50 and 70% of the sediment succession is dominated by ice-rafted sediment, although rhythmites, matrix-rich gravels, sands and graded sand–silt couplets are also present. A range of intra-formational, soft-sediment deformation structures are present, consistent with liquefaction and deformation associated with loading, current shear, and iceberg calving. The landform–sediment assemblages described from Heinabergsjokull provide important data for the interpretation of Pleistocene ice-dammed lakes.

This paper documents the glaciological structures associated with the surge of Skeiðarárjökull, Iceland, in 1991. These structures are interpreted as units of stratified ice, low-angle fractures, vertical and sub-vertical fractures (crevasse traces) and thrusts. The inferred thrusts are debris-rich and, unusually, have both down-glacier and up-glacier dips close to the ice margin. Sediment infills consist of either massive sand or horizontally stratified sand units. The most significant debris-rich structures on the glacier surface, however, are supraglacial crevasse and conduit fills, which contain either massive or horizontally stratified silts, sands and granule-gravels. These sediments infill both vertical fractures (relict crevasses) and englacial conduits. At the stratigraphic base of these sediment fills there is evidence of syn-sedimentary deformation, suggesting that sedimentation occurred during crevasse closure and continued thereafter. We argue that these structures relate to an episode of supraglacial meltwater flow during the 1991 surge, caused by the build-up of subglacial water pressure in a linked-cavity system or some similar distributed drainage system beneath the glacier. The development of this high-level drainage route may have helped regulate basal water pressures and therefore the active phase of the surge. The idea that the supraglacial leakage of subglacial water may have played a role in terminating the surge is explored.

The available published and unpublished archaeological record (human and animal bones, artefacts, footprints) is collated and reviewed in relation to the stratigraphic succession and palaeoecology for Mid-Holocene marginal coastal environments around Liverpool Bay. Two stratigraphic levels with human and animal footprint trails are described from Formby Point and whilst the upper level was formed between c 4000–3600 years B.P. (during the later Neolithic-early Bronze Age), the lower level is older. The animal and bone assemblages and the archaeological artefact evidence for this coastal region are reviewed. The implications of these finds for inter-tidal zone archaeology for this region are assessed but it appears that there is no evidence for major Mesolithic coastal human or animal activity, except for the North Wales coast, although there are major concentrations of Neolithic animal, human and artefacts remains. During the Bronze to Iron Age dunes were present and probably grazed. Metal artefacts have been located from several sites but there is a lack of associated pottery evidence throughout the Holocene. This may mean that settlements were inland and coastal areas were only visited for grazing, hunting and fishing.

This paper describes the landform and sediment assemblage produced by a surge (in 1948) of the Kongsvegen/Kronebreen tidewater glacier complex in northwest Spitsbergen. The main geomorphological products of this advance are two large thrustmoraine complexes on opposite sides of the fjord, and a system of geometrical ridges revealed on glacier decay. The thrust-moraines are composed largely of diamicton, sandy and muddy gravel, gravelly sand, sand and mud, with minor laminites. All of these appear to be derived from the fjord floor and represent both fine fjord basin sediments and coarse grounding-line fan deposits. Thrusting was the principal mode of emplacement of the sediment onto the adjacent land areas during the 1948 advance. However, the geomorphology of the thrust-moraine complexes on either side of the fjord is quite different, reflecting a transpressive regime on the southwest side (mainly long ridges) and a normal compressive regime on the northeast side (short ridges and pinnacles of a ‘hummocky’ nature). The advance which produced the moraine complex has previously been attributed to a surge of Kongsvegen, but the glaciological and geomorphological evidence suggests that the advance involved both Kongsvegen and Kronebreen. Comparison of the landform assemblage produced by this event with that produced by other tidewater glacier surges demonstrates the diverse range of landform assemblages associated with glacier surges, or other episodes of rapid flow, within glaciomarine environments.

Marthabreen is a 7 8km long valley glacier in SW Spitsbergen. The glacier is partially covered by a layer of angular debris derived from rockfall in its accumulation area, pierced in places by pinnacles and ridges of glaciofluvial sediment. These concentrations of glaciofluvial sediment fall into three categories: (1) debris pinnacles; (2) longitudinal sediment dykes; (3) longitudinal ridge accumulations. Debris pinnacles are slabs of sediment (predominantly sands, gravels and cobbles) elevated to the glacier surface along thrusts. Longitudinal sediment dykes are low ( 1m high) ridges of sorted sand and gravels which are not associated with penetrative ice structures. Their occurrence downglacier of sediment dykes and debris pinnacles suggests that they originate as supraglacial or englacial channels or tunnels filled by sediment derived from the dykes or thrusts. The presence of large quantities of glaciofluvial sediment on the surface of Marthabreen does not imply englacial water flow at high levels within the glacier, but is related to ice deformational processes such as thrusting and folding of debris-rich stratification. Copyright # 1999 John Wiley & Sons, Ltd.

Human and animal footprints and tracks exposed in the intertidal zone on the Formby coast are described. Their distribution, age and stratigraphic and palaeoecological setting in relation to Holocene coastal environmental change is discussed. The regional significance of these prints and their relationship to human and animal bones found in the intertidal zone is discussed and their relationship to the local archaeological record is summarised.

The interpretation of glacigenic diamictons is a subjective process, for which quantitative support is frequently sought from parameters such as clast shape and fabric. It has been widely suggested that different glacigenic diamicton facies possess distinct clast-fabric signatures. This paper examines this concept using a data set of 111 clast fabrics, and a synthesis of published results. Eigenvalues are calculated and compared for a variety sedimentary facies. It is concluded that clast fabric alone is not able to discriminate between different glacigenic facies, and it is argued that clast fabric offers little quantitative support in the interpretation of glacigenic sediments. It is suggested, therefore, that although clast fabric may continue to have a role as an indicator of relative strain at specific sites, its use in the discrimination of glacigenic facies is limited. Consequently, we should be much more selective in undertaking such analyses in the future. Copyright © 1999 John Wiley & Sons, Ltd.

Three moraine complexes containing large rafts of fractured-bedrock formed by small cirque glaciers occur in Reindalen, Svalbard. Glaciotectonic landforms cored by rock rafts have been described from mid-latitude ice sheets of Pleistocene age in the past, but we believe this to be the first time large-scale bedrock rafts have been reported from moraines formed by small cirque glaciers. These moraine complexes consist of an imbricate stack of thrust slabs composed of fractured-bedrock and diamicton. Although the exact mechanism are unclear, we suggest that these moraines form by the displacement of subhorizontal strata within the cirque floor to form an initial stack of rock-cored thrust slabs, which subsequently confine the cirque glacier. Subsequent glacier advances, against this "barrier," establishes a strong compressive regime within the glacier snout, which leads to erosion and moraine development. Estimates of the thickness of the rock rafts are used to derive erosion rates, which are an order of magnitude greater than those previously reported for arctic regions.

Modes of debris entrainment and subsequent transfer in seven “normal” and five surge-type glaciers in Svalbard (76–79° N) are outlined in the context of the structural evolution of a glacier as the ice deforms during flow. Three main modes of entrainment and transfer are inferred from structural and sedimentological observations: (i) The incorporation of angular rockfall material within the stratified sequence of snow/firn/superimposed ice. This debris takes an englacial path through the glacier, becoming folded. At the margins and at the boundaries of flow units the stratified ice including debris is strongly folded, so that near the snout the debris emerges at the surface on the hinges and limbs of the folds, producing medial moraines which merge towards the snout. The resulting lines of debris are transmitted to the proglacial area in the form of regular trains of angular debris. (ii) Incorporation of debris of both supraglacial and basal character within longitudinal foliation. This is particularly evident at the surface of the glacier at the margins or at flow unit boundaries. It can be sometimes demonstrated that foliation is a product of strong folding, since it usually has an axial planar relationship with folded stratification. Foliation-parallel debris thus represents a more advanced stage of deformation than in (i). Although the presence of basal debris is problematic, it is proposed that this material is tightly folded ice derived from the bed in the manner of disharmonie folding. The readily deformed subglacial sediment or bedrock surface represents the plane of décollement. (iii) Thrusting, whereby debris-rich basal ice (including regelation ice) and subglacial sediments are uplifted into an englacial position, sometimes emerging at the ice surface. This material is much more variable in character than that derived from rockfalls, and reflects the substrate lithologies; diamicton with striated clasts and sandy gravels are the most common facies represented. Thrusting is a dynamic process, and in polythermal glaciers is probably linked mainly to the transition from sliding to frozen bed conditions. It is not therefore a solely ice-marginal or proglacial process.

Well-rounded gravels are described from moraine-mound complexes, diamicton forefields and modern englacial thrusts at the margins of four glaciers on the northern side of Broggerhalvoya, northwest Spitsbergen. Their shape charcteristics are compared with modern and fossil glacigenic, modern beach and Early Weichselian beach gravels from this peninsula. The best discriminators of the well-rounded gravels have been found to be the percentage-frequency roundness histograms, the roundness mid-point and roundness range diagrams and the sphericity-roundness plots. It is concluded that the gravels have been derived by englacial thrusting from Early Weichselian or last interglacial beaches in the inner parts of the fjord and in the low level cirques when sea level reached at least 50m a.s.l. and deposited the beach gravels. The discrimination between gravel in basal diamictons, proglacial outwash and modern beaches is difficult as the reworking has resulted in little particle shape change. The potential major problem caused by reworking in the glacial environment is emphasised, especially when clast shape comparisons from modern environments to older sediments are used.

Although there is an established relationship between geological structure and the morphology of certain glacial erosional landforms, the role of lithology is less clear. This is particularly true of the surface wear characteristics of glaciated bedrock. In order to examine this relationship, the surface wear characteristics of eight recently deglaciated metamorphic bedrock slabs in the Kongsfjorden area of Svalbard were mapped and recorded using detailed “micro‐maps.” Features recorded included lee‐side fracture surfaces, lee‐side cavities, and the location and depth of open joints and quartz veins. On schist, glacial erosion is favored by situations where ice movement is parallel to the trend of the bedrock foliation. In these situations, cavities may be elongated in the direction of ice flow. On more homogeneous lithologies such as marble, cavity formation is suppressed and more uniform glacially abraded rock surfaces develop. On all the metamorphic rocks examined, glacial abrasion is favored in situat...

Mapping of the structural glaciology of Kongsvegen, Svalbard, reveals evidence for four main deformational structures. These are stratification, longitudinal foliation, thrusts and crevasse traces. These structures are considered in terms of their contribution to debris entrainment, transport and subsequent landform development. Stratification is associated with small amounts of supraglacial debris that has been folded with flow-parallel axes; longitudinal foliation in places incorporates basal glacial sediments along folds with flow-parallel axes; and thrusts transport basal debris to the glacier surface. Crevasse traces are not significant in terms of debris entrainment. The entrainment of basal debris along longitudinal foliation is not a universally recognised process. At Kongsvegen this process is attributed to the development of a transposition foliation, in combination with incorporation of debris-rich basal ice or soft basal sediment in the fold complex. Mapping of the landforms in the proglacial area shows that debris incorporated along longitudinal foliation is released as “foliation-parallel ridges” and that transverse ridges mark debris-bearing thrusts. The role of longitudinal foliation in landform development has never been documented in this manner. Although the preservation potential of such ridges may be limited, recognition of foliation-parallel ridges in the Pleistocene landform record has important implications for the interpretation of the dynamics of former ire masses.

Irregular mounds of glacial debris, commonly referred to as 9hummocky moraine9, until recently were linked to ice stagnation during rapid climatic amelioration. However, recent work in Scotland has demonstrated that some hummocky moraine, dating from the Younger Dryas event ( c. 10 000 years BP ), was the product of deposition at active ice margins. Observations at modern high–arctic glacier margins in Svalbard (76–80°N) indicate that some moraines of this type form under a dynamic glaciological regime, mainly by thrusting in active polythermal ice undergoing strong longitudinal compression. This situation is particularly common where there is a transition from warm–based ice in the interior of a glacier to cold–based ice at the margins or snout. From their morphological similarity (rectilinear slopes facing up–glacier and irregular downglacier faces), and apparent stacking of slabs of sediment of subglacial derivation, it is concluded that some assemblages of British moraines are also the product of thrusting. This process appears to be most dominant in polythermal glaciers, rather than in temperate glaciers. On this basis, it is tentatively suggested that the Younger Dryas in Britain was characterized by a climatic regime similar to that in Svalbard today (mean annual temperature − 5°C; 400–1000 mm precipitation), and that the associated glaciers may have been of polythermal character.

The formation of a moraine mound (hummocky moraine) complex at the Neoglacial limit of Pedersenbreen, Svalbard is discussed. The moraine mounds are composed for the most part of sheared basal diami...

Traditionally, geometrical ridge networks are interpreted as the product of the flow of subglacial sediment into open basal crevasses at the cessation of a glacier surge (‘crevasse-fill’ ridges). They are widely regarded as a characteristic landform of glacier surges. Understanding the range of processes by which these ridge networks form is therefore of importance in the recognition of palaeosurges within the landform record. The geometrical ridge network at the surge-type glacier Kongsvegen in Svalbard, does not form by crevasse filling. The networks consist of transverse and longitudinal ridges that can be seen forming at the current ice margin. The transverse ridges form as a result of the incorporation of basal debris along thrust planes within the ice. The thrusts were apparently formed during a glacier surge in 1948. Longitudinal ridges form through the meltout of elongated pods of debris, which on the glacier surface are subparallel to the ice foliation and pre-date the surge. This work adds to the range of landforms associated with glacier surges.

The Holocene mud-flats of Formby Point, at the mouth of the Mersey estuary in northwest England, have long provided information about their palaeoenvironment. Now they yield a more direct evidence — in the form of preserved footprints — of the people and animals that frequented the foreshore.

Many glaciers in Svalbard, which tend to be thermally complex with both warm and cold ice, produced complex ‘push moraines’ or ‘thrust-moraine complexes’ at the time of their maximum neoglacial advance, and during their subsequent recession. Uvěrsbreen, which nearly reaches the coast of northwest Spitsbergen, has a push moraine 50 m high, comprising gravel and sand of fluvial origin, and diamicton derived from basal ice, as well as thrust masses of dead ice. The push moraine is almost entirely a product of the tectonic processes, especially thrusting, that occurred in the snout of the glacier and in the frozen sediments immediately in Journal of Quaternary Science front. Thrusting is probably initiated where the glacier switches from a sliding mode to a state of being frozen to the bed. Thrusting in the foreland is an extension of the same processes that occur within the ice itself, and a sole thrust probably extends from the frozen sediment that underlies the base of the glacier near its snout. Thrusting results in subglacial sediment being uplifted to a high level within the glacier or even to the surface. Subsidiary near-horizontal thrusts parallel to the bedding plane link thrusts dipping up-glacier, and result in local thickening of individual subglacial sedimentary units. Gravels incorporated in this way retain their integrity but sands are folded, whereas uplifted debris-rich basal ice is intensely folded. The distinctive tectonic style of low-dip bedding in gravels, truncated by high-angle (30–40°) thrusts, and only localised folding in less competent material, differs from most descriptions of such ridges, but may be typical of many push moraines composed principally of fluvial material.

Postcolonialism is a notoriously problematic term, but throughout debates on its utility there runs the assumption that, whatever it is, it must be political. Postcolonial theory, distinguished from postcolonialism, appears to have left behind the Marxist categories of much anti-colonial thought in favour of various kinds of post-structuralism, usually associated with Derrida and Foucault. That move now appears problematic to many in the field because it apparently leads to de-politicization, and so there is a need to draw upon other modes of thought. One possibility would be to return to histories of politically engaged thought, to renew postcolonialism’s energies through a more clear-sighted sense of what political criticism might be. Many critics have taken an alternative route, engaging more fully with some of the philosophical names associated with French philosophy, principally Gilles Deleuze. Indeed, it is clear that postcolonial studies has entered a new stage in its reception of Deleuze’s work, with increasingly systematic attention being given to its implications for postcolonial practices. Increasingly, critics have brought Deleuze and postcolonial studies together in an explicit and sustained manner, as can be seen in the recent collection Deleuze and the Postcolonial (2010). Bignall and Patton summarize the aim of that volume when they write that, ‘[p]roperly mutual negotiations witness the simultaneous becoming-Deleuzian of postcolonialism and the becoming-postcolonial of Deleuze’ (2010, p. 12).

The timing and origin of the earliest human colonization of the Americas has been the subject of great debate over the last 100 years and is still a matter of heated discussion today (Renne et al., 2005; Gonzalez et al., 2006a). It is widely accepted that the Clovis culture was the first to migrate into the New World at 13.1 ka (Waters and Stafford, 2007). However, archaeological evidence, in the form of stone tools, linguistics, craniometrics and genetics all suggest that the first Americans were ethnically diverse, and a few sites dated to 15e16 ka challenge the ‘Clovis First’ model (Goebel et al., 2008). Perhaps the most spectacular challenge to the ‘Clovis First’ model was the reported presence of human footprints within a basaltic ash (Xalnene Ash, Valsequillo Basin, Central Mexico), dated to 38.04 8.57 ka using optically stimulated luminescence (OSL; Gonzalez et al., 2006a). However, Renne et al. (2005) challenged the validity of the footprints by dating lapilli from the Xalnene Ash using 40Ar/39Ar and reported an age of 1.30 0.03 Ma (2s). Renne et al. (2005) also reported a reversed palaeomagnetic polarity for the ash, consistent with deposition during chron C1r.2r (Cande and Kent, 1995). Such antiquity casts considerable doubt on the interpretation of the impressions as human footprints. Gonzalez et al. (2006b) questioned the 40Ar/39Ar age and highlighted the heterogeneous nature of the lapilli as a potential problem for 40Ar/39Ar geochronology. The lapilli contain phenocrysts and include xenocrysts. Olivine phenocrysts can be contaminated with excess Ar (ArE; McDougall et al., 1969) and hence the dating of

Fridtjovbreen is an actively surging tidewater glacier in western Spitsbergen, Svalbard. This paper presents observations made at the western flank of the glacier in July 1997, when the glacier front was still advancing rapidly and was characterised by steep lateral ice cliffs. The geomorphological consequences of the surge include the formation of push moraines from toppled ice blocks along this ice cliff and the development of debris-rich thrusts. There is also evidence of glaciotectonic deformation within deformed debris-rich thrusts. Thrusts are restricted to the lateral margins and are not seen in the terminal calving cliff. On its western flank, Fridtjovbreen is over-riding Sagabreen, a small-tributary glacier. Large facies variations in this area are a result of recycling by Fridtjovbreen of material originally transported as medial moraines on Sagabreen. There are few observations of landform development at actively surging glaciers in Svalbard. The Fridtjovbreen descriptions provide documentation for post-surge landform development. More observations are required at the margins of actively surging glaciers to determine how representative Fridtjovbreen is of a surge event.

Well-rounded gravels are described from moraine-mound complexes, diamicton forefields and modern englacial thrusts at the margins of four glaciers on the northern side of Brøggerhalvøya, northwest Spitsbergen. Their shape charcteristics are compared with modern and fossil glacigenic, modern beach and Early Weichselian beach gravels from this peninsula. The best discriminators of the well-rounded gravels have been found to be the percentage-frequency roundness histograms, the roundness mid-point and roundness range diagrams and the sphericity-roundness plots. It is concluded that the gravels have been derived by englacial thrusting from Early Weichselian or last interglacial beaches in the inner parts of the fjord and in the low level cirques when sea level reached at least 50m a.s.l. and deposited the beach gravels. The discrimination between gravel in basal diamictons, proglacial outwash and modern beaches is difficult as the reworking has resulted in little particle shape change. The potential major problem caused by reworking in the glacial environment is emphasised, especially when clast shape comparisons from modern environments to older sediments are used.

Clast shape data from a range of different glacial environments at several high-arctic valley glaciers in Svalbard are presented. These data add to the growing body of reference information about clast shape in modern glacial environments and is used to explore the role of lithology in clast morphogenesis and to evaluate the different methodological approaches to the analysis of clast shape data. The following conclusions are drawn: (1) it is possible to distinguish clasts transported subglacially from those moved supraglacially; (2) it is not possible to differentiate among different types of subglacial sediment or to distinguish them collectively from glaciofluvial samples; (3) lithology has some influence on clast shape, although not as much as previously suggested; and (4) covaria t plots of the RA (percentage of angular and very angular clasts) versus C40 (percentage of clasts with c to a axial ratio

The role of rock type in controlling downstream variation in clast parameters in non-jokulhlaup-affected, Oraefi sandar in Iceland was evaluated. Clast changes in the Svinafellsa are simple, but the effects of tributary sources complicate the clast parameter-distance relationships in the Morsardalur-Kjos system. The behavior of individual rock types must be studied to understand the changes. Both selective sorting and abrasion are taking place, and the relative importance of these processes is evaluated. The volcanic rocks are rounding relatively rapidly, with variation among individual rock types, but there are no significant changes in sphericity and clast form with distance. The compressive strength of the volcanic suite is variable, and significant weathering changes must be takin place during transport from rock face to distal sandur. The influence of such weathering changes on changes in clast parameters needs further research.

SummaryThe sand/matrix ratio technique is described and has been shown to provide a rapid method of correlating till units in the Cumberland lowland which belong to separate glacial phases. Basal tills have a relatively constant sand/silt-matrix ratio compared with flowage tills in the same locality.

The form and stratigraphy of dominat pro glacial deposits is described and analysed for three distinct environments at a lobe of the inland ice: (i) an ice floored basin with terraced sediments at ...