Late Devensian ice sheet characteristics: a palaeohydraulic approach

Glacial meltwater channels are incised into bedrock and diamicton along much of the length of the Mid-Cheshire Ridge. Detailed mapping of one such system near the town of Helsby reveals a dendritic channel network developed in the opposite direction to the regional ice flow during the last (Late Devensian) glaciation. The channels formed subglacially, under atmospheric and not hydrostatic pressure, presumably as the ice sheet downwasted during deglaciation. Morphological and palaeohydraulic evidence suggests that not all of the network was necessarily active contemporaneously. Former water levels in the channels can be estimated due to the presence of bar surfaces, giving a calculated palaeodischarge of at least 111 m³ s⁻¹. The ablation rates required to account for this large discharge are an order of magnitude greater than those obtained from theoretical calculations and those observed in modern glacial environments. This implies that some form of high-magnitude discharge, such as a seasonal flood event, must have taken place in this area during deglaciation. This picture of the Late Devensian ice sheet suggests that during recession the ice sheet was static, crevassed and relatively thin (<50 m). This study also shows that there is no simple relationship between meltwater channel direction and ice dynamics, and that care is required when using the former to make inferences about the latter. Copyright © 1998 John Wiley & Sons, Ltd.     

The ice/bed interface mosaic: deforming spots intervening with stable areas under the fringe of the Scandinavian Ice Sheet at Sampława,Poland

The glacial sediment succession exposed close to the southern margin of the Late Weichselian Scandinavian Ice Sheet in Poland reveals a mosaic consisting of isolated patches of heavily deformed deposits separated by areas lacking any visible evidence of deformation. In the studied outcrop, the subglacial deforming spots composed of outwash deposits intercalated with till stringers are about 2–10 m wide and 20–60 cm thick. They rest on outwash sediments and are covered by a basal till. Based on structural and textural characteristics, the deforming spots are interpreted as previous R‐channels filled with meltwater deposits. Lack of deformation in outwash sediment immediately beneath the deforming spots and in the intervening areas between the channels suggests that the ice‐bed was frozen and the deformation of the channel infill was facilitated by high pore‐water pressure arising because water drainage into the bed was impeded by permafrost. Channel infill deposits and the till immediately above were coevally deformed to a strain of less than 9. This study documents the possible co‐existence of deforming and stable areas under an ice sheet, generated by spatially varying thermal and hydrological conditions affecting sediment rheology.     

Temporal changes in subglacial meltwater activity: field evidence from the late Devensian in the north of Ireland

Temporal changes in meltwater abundance, distribution and characteristics (controlling subglacial processes and ice sheet dynamics) can be inferred from subglacial sediment successions. Field evidence for changes in subglacial meltwater characteristics over time is presented from two sites (Doonan, Drummee) near a former late Weichselian (Devensian) ice centre in the north of Ireland. On a macroscale, both sites investigated show subglacial diamicton overlying glacially planated bedrock platforms. In more detail, primary sedimentary structures and facies variability show a complex relationship between depositional processes and meltwater characteristics at the ice/bed interface (IBI). Sedimentary evidence suggests sediment transport and deposition took place by low-viscosity subglacial slurries (mobile sediment–meltwater admixtures), which are part of a continuum between the processes of subglacial sediment deformation and subglacial meltwater flooding. Subtle changes in meltwater abundance and distribution at the IBI controlled slurry rheology, mechanisms of particle support and detailed sediment depositional processes.     

The extension of the Late Weichselian/Late Devensian ice sheets in the North Sea Basin

The distribution of large channel-like features, comprising Weichselian/Devensian incisions, in the western North Sea provides evidence for a much larger extension of the last ice sheet than currently assumed. Morphological comparison of the incisions with those in North Germany and Poland reveals a striking similarity in shape and distribution. The features on the North Sea floor are interpreted as being formed by meltwater erosion within the margin of the ice sheet. The widespread absence of Weichselian/Devensian till in the area under consideration may be attributed to later erosion. Large-scale reworking and redistribution of sediments is indicated by the complete sediment infill of the majority of the incisions.     

Dimensions and deglacial chronology of the Outer Hebrides Ice Cap,northwest Scotland: implications of cosmic ray exposure dating

Cosmic ray exposure ages of frost-weathered bedrock from mountain summits in the Outer Hebrides exceed the age of Late Devensian glaciation. Exposure ages of most glacially-abraded bedrock surfaces at low and intermediate elevations are younger than the age of maximum Late Devensian glaciation. These results confirm that previously mapped periglacial trimlines in the Outer Hebrides define the upper limit of bedrock erosion by Late Devensian ice. They are consistent with the interpretation, based on geomorphological evidence, that the trimlines mark the approximate upper limit of a Late Devensian Outer Hebrides Ice Cap. A postglacial exposure age from the summit of Oreval (662 m) suggests that this mountain was overrun during the last glaciation, indicating thicker ice cover and a lower surface gradient west of the ice-cap divide than previously inferred. Although bedrock surfaces below the trimlines are strongly ice-moulded, some show evidence of prior cosmic ray exposure, which we attribute to limited erosion during Late Devensian glaciation. If this interpretation is correct, the youngest apparent ages from these surfaces give the most reliable dates for deglaciation, at ca. 14.5–14 ka. This implies that ice persisted at favourable sites through the warm opening phase of the Windermere Interstade. Comparison with radiocarbon-dated evidence from offshore cores suggests net ice margin retreat of ∼74 km eastwards across the adjacent shelf in > 2.3 ± 1.0 ka. The dating evidence is consistent with relatively rapid retreat of calving margins to the coast, then slower withdrawal of ice margins to high ground. Copyright © 2005 John Wiley & Sons, Ltd.     

Origin and significance of lateral meltwater channels formed along a temperate glacier margin, Glacier Bay, Alaska

Pleistocene lateral meltwater channels are commonly used as evidence of cold-based or polythermal ice. However, lateral meltwater channel formation has been observed for >40 years along the margins of a rapidly thinning temperate glacier in Glacier Bay, Alaska. Flights of nested linear lateral meltwater channels and in-and-out channels have formed on the sides of emerging nunataks. Nested channels at Burroughs Glacier are up to 200 m long; they are good proxies for the slope of the ice margin along the land surface and are terminated by subglacial chutes. A perched water table associated with precipitation and high ablation rates in the temperate ice causes surface meltwater to flow toward the margin above less permeable ice. The water flows along the margin and erodes lateral meltwater channels until a subglacial chute carries the water into the subglacial water system. Rates of channel formation range from 0 to 8 channels/year. Spacing and rates of channel formation are controlled by the land-surface slope, ablation rate, erodibility of the substrate and stream discharge. Because lateral meltwater channels have been observed forming along a temperate glacier margin, care must be exercised when using the presence of lateral meltwater channels as definitive evidence of cold-based or polythermal ice.     

Drainage beneath ice sheets: groundwater–channel coupling,and the origin of esker systems from former ice sheets

The nature of the drainage system beneath ice sheets is crucial to their dynamic behaviour but remains problematic. An experimentally based theory of coupling between groundwater and major channel systems is applied to the esker systems in the area occupied the last ice sheet in Europe, which we regard as a fossil imprint of major longitudinal drainage channels. We conclude that the large-scale distribution and spacing of major eskers is consistent with the theory of groundwater control, in which esker spacing is partly controlled by the transmissivity of the bed.It is concluded that esker patterns reflect the large-scale organisation of the subglacial drainage pattern in which channel development is coupled to groundwater flow and to the ice sheet's dynamic regime. The theory is then used to deduce: basal meltwater recharge rates and their spatial variability from esker spacing in an area in which the ice sheet was actively streaming during its final retreat; patterns of palaeo-groundwater flow and head distribution; and the seasonally varying magnitude of discharge from stream tunnels at the retreating ice sheet margin. Major channel/esker systems appear to have been stable at least over several hundred of years during the retreat of the ice sheet, although major dynamic events are demonstrably associated with major shifts in the hydraulic regime.Modelling suggests: that glaciation can stimulate deep groundwater circulation cells that are spatially linked to channel locations, with groundwater flow predominantly transverse to ice flow; that the circulation pattern has the potential to create large-scale anomalies in groundwater chemistry; and that the spacing of channels will change through the glacial cycle, influencing water pressures in stream tunnels, subglacial hydraulic gradients and effective pressure. If the latter is reduced sufficiently, it could trigger enhanced bed deformation, thus coupling drainage to ice sheet movement. It suggests the possibility of distinctive phases of sediment deformation and drumlin mobilisation during a glacial cycle.     

The sediment infill of subglacial meltwater channels on the West Antarctic continental shelf

Subglacial meltwater plays a significant yet poorly understood role in the dynamics of the Antarctic ice sheets. Here we present new swath bathymetry from the western Amundsen Sea Embayment, West Antarctica, showing meltwater channels eroded into acoustic basement. Their morphological characteristics and size are consistent with incision by subglacial meltwater. To understand how and when these channels formed we have investigated the infill of three channels. Diamictons deposited beneath or proximal to an expanded grounded West Antarctic Ice Sheet are present in two of the channels and these are overlain by glaciomarine sediments deposited after deglaciation. The sediment core from the third channel recovered a turbidite sequence also deposited after the last deglaciation. The presence of deformation till at one core site and the absence of typical meltwater deposits (e.g., sorted sands and gravels) in all three cores suggest that channel incision pre-dates overriding by fast flowing grounded ice during the last glacial period. Given the overall scale of the channels and their incision into bedrock, it is likely that the channels formed over multiple glaciations, possibly since the Miocene, and have been reoccupied on several occasions. This also implies that the channels have survived numerous advances and retreats of grounded ice.     

On the history of the Late Devensian Lake Sparks in southern Fenland,Cambridgeshire, England

A section in a gravel quarry at Somersham, Cambridgeshire, has revealed evidence for a lake, named Lake Sparks, in Fenland during the Late Devensian substage of the Pleistocene. Varved sediments were deposited in this lake over a minimum period of ca. 65 yr. The varved clays contain red diamicton clasts, interpreted as dump, delivered to the area by icebergs or floes from the ice-front in the Wash that deposited the Hunstanton Till. The lake is therefore considered a result of impounding by the Late Devensian ice advance on the east coast. A small number of pale varves have a characteristic structure indicating increased calcite deposition in the summer. They are interpreted as a result of cooler summers with reduced gelifluction from the surrounding Jurassic (Ampthill) Clay. Such gelifluction introduced a mudflow into the varved sequence at the southern end of the section. Pollen analysis confirms the derivation of the clays from the surrounding Ampthill Clay. The varved clays are succeeded by fluviatile sediments related to a delta building into the lake from the north. The delta sediments show periodic influx of sand into the lake interrupted by quiet periods with the development of Chara meadows. A thin spread of fluviatile gravels succeed the delta sediments, indicating the development of a braided river plain as the lake drained on the melting of the Late Devensian ice. This was followed by permafrost development, with the formation of thin thermal contraction cracks and coversand deposition. Later, degradation of the permafrost was associated with the formation of diapirs and a solifluction mantle, and incision of the fluviatile and lacustrine sediments took place. Flandrian peat and marl later filled the valley so formed. A radiocarbon date of 18310 yr BP from Salix leaves in a drift mud at the top of channel sands preceding lake sediment, in a neighbouring section, confirms the relation of the lake to the Late Devensian ice advance. The significance of the Late Devensian sediments at Somersham lies in the information they give on the timing and variety of processes related to drainage and ice movement in the period before, during and after the ice advance to the Wash. A period of low deposition rate in the lake was followed by rapid delta sedimentation and lake drainage, with implications for climatic change.     

The origin and glaciodynamic significance of sandstone ridge networks from the Hirnantian glaciation of the Djado Basin (Niger)

The Djado Basin (Niger) was located beneath the inner part of the Late Ordovician ice sheet. The Felar‐Felar Formation consists mainly of glaciomarine deposits, associated with the major ice sheet recession within the glaciation, and is bounded by two glacial unconformities. Structures corresponding to sandstone ridges are found within the Felar‐Felar Formation. Sandstone ridges are several metres high, about 10 m wide and hundreds of metres long. These structures are organized in extensive anastomosed to sub‐polygonal networks. The association of sandstone ridge networks with the later glacial unconformity and with other glacial evidence suggests sub‐glacial conditions for their origin. Sandstone ridge sedimentological characteristics indicate that sandstone ridges result from the scouring of the Felar‐Felar Formation by sub‐glacial, turbulent and pressurized meltwater; then sub‐glacial cavities were infilled with sand derived from glacial abrasion. Sandstone ridge networks are comparable with tunnel channels and document unusual drainage structures of the inner part of the palaeo‐ice sheet.     

Periglacial trimlines,former nunataks and the altitude of the last ice sheet in Wester Ross,northwest Scotland

High-level weathering limits separating ice-scoured topography from frost-weathered detritus were identified on 28 mountains in Wester Ross at altitudes of 700–960 m, and a further 22 peaks support evidence of ice scouring to summit level. Weathering limits are defined most clearly on sandstone and gneiss, which have resisted frost shattering during the Late Devensian Lateglacial, but can also be distinguished on schists and quartzite. Schmidt hammer measurements and analyses of clay mineral assemblages indicate significantly more advanced rock and soil weathering above the weathering limits. The persistence of gibbsite above weathering limits indicates that they represent the upper limit of Late Devensian glacial erosion. The regular decline of weathering-limit altitudes along former flowlines eliminates the possibility that the weathering limits represent former thermal boundaries between protective cold-based and erosive warm-based ice. The weathering limits are therefore interpreted as periglacial trimlines that define the maximum surface altitude of the last ice sheet. Calculated basal shear stresses of 50–95 kPa are consistent with this interpretation. Reconstruction of ice-sheet configuration indicates that the former ice-shed lay above 900 m along the present watershed, and that the ice surface descended northwestwards, with broad depressions along major troughs and localised domes around independent centres of ice dispersal. Extrapolation of the ice surface gradient and altitude suggests that the ice sheet did not overrun the Outer Hebrides, but was confluent with the independent Outer Hebrides ice-cap in the North Minch basin. Erratics located up to 140 m above the reconstructed ice surface are inferred to have been emplaced by a pre-Late Devensian ice sheet (or ice sheets) of unknown age. © 1997 John Wiley & Sons, Ltd.     

Devensian organic interstadial deposits and ice sheet extent in Buchan,Scotland

Pre-Late Devensian organic deposits in the Buchan area of northeast Scotland were investigated for their geomorphological and palaeoecological (pollen, plant macrofossils, coleoptera) properties. Close ecological agreement exists between fossil indicators and allows the inference that the environment in the vicinity of the deposits was a dwarf shrub tundra of the type met today in high latitude areas of Scandinavia and arctic Russia. The latest in a series of radiocarbon dates from the site produced determinations beyond the limits of the method, although the geomorphological and fossil evidence appears to point to an interstadial date within Oxygen Isotope Stages 5a or 5c. The site has special significance for arguments concerning the much-debated concept of ‘Moraineless Buchan’; indeed, evidence is presented which supports the concept of extensive ice sheet glaciation during the Late Devensian for this crucial geographical area. If Buchan is to be seen as a further casualty amongst other disputed ice-free enclaves, then a return to earlier models of extensive ice sheet glaciation in the Late Devensian of Scotland would seem to be necessary. © 1998 John Wiley & Sons, Ltd.     

Glacitectonic evidence of ice sheet interaction and retreat across the western part of Dogger Bank (North Sea) during the Last Glaciation

High-resolution 2D seismic data from the western side of Dogger Bank (North Sea) has revealed that the glacigenic sediments of the Dogger Bank Formation record a complex history of sedimentation and penecontemporaneous, large-scale, ice-marginal to proglacial glacitectonism. The resulting complex assemblage of glacial landforms and sediments record the interplay between two separate ice masses revealing that Late Devensian ice sheet dynamics across Dogger Bank were far more complex than previously thought, involving the North Sea lobe of the British and Irish Ice Sheet, advancing from the west, interacting with the Dogger Bank lobe which expanded from the north. The active northward retreat of the Dogger Bank lobe resulted in the development of a complex assemblage of arcuate thrust-block moraines (≤ 15 km wide, > 30 km long) composed of highly folded and thrust sediments, separated by sedimentary basins and meltwater channels filled by outwash. The impact of the North Sea lobe was restricted to the western margin of Dogger Bank and led to deep-seated (100–150 m thick) glacitectonism in response to ice-push from the west. During the earlier expansion of the North Sea lobe, this thrust and fold complex initially occupied a frontal marginal position changing to a more lateral ice-marginal position as the ice sheet continued to expand to the south. The complex structural relationships between the two glacitectonic complexes indicates that these ice masses interacted along the western side of Dogger Bank, with the inundation of this area by ice probably occurring during the last glaciation when the ice sheets attained their maximum extents.     

Glacial meltwater erosion and sedimentation as evidence for multiple glaciations in west Wales

This article presents the results of a geomorphological and sedimentological investigation of former glacial meltwater drainage in the region of the lower Afon Teifi, one of the major rivers of southwest Wales. Former drainage characteristics in the region are reconstructed concentrating on palaeo-drainage routes associated with successive Pleistocene glaciations and their role in the Quaternary evolution of the lower Teifi. Mapping of these features throughout a c. 100 km ² area reveals a complex evolution in the establishment of the present-day drainage system, with evidence for the following surface channel types: (i) type 1 channels of primary subglacial origin cut during the late Devensian (late Wisconsinan/late Weichselian) glaciation; (ii) type 2 channels representing either pre-late Devensian subaerial fluvial run-off, unconnected to the course of the preglacial Afon Teifi, or originating as subglacial chute channels; (iii) type 3 channels developed as subglacially modified pre-late Devensian tributaries of the Afon Teifi. Two further features are also described: (iv) type 4 channels are drift-plugged abandoned preglacial courses of the Afon Teifi, and (v) type 5 channels formed as lateglacial and post-late Devensian gorges which bypass type 4 channels. A relative chronostratigraphy based on channel geomorphology and sedimentology reveals an evolutionary sequence considerably more complicated than identified in previous studies, with extensive modification of the lower Afon Teifi region by glacial meltwater during at least two periods of Pleistocene glaciation.     

Late Devensian raised shorelines and ice limits in the inner Moray Firth area, northern Scotland

Marine, fluvial and fluvioglacial landforms and the deposits associated with them, have been mapped in the inner Moray Firth area. The landforms identified indicate a close association between the decay of the Late Devensian Scottish ice sheet and the formation of raised marine features. Analysis of the altitudes of the marine terraces has identified ten glacio-isostatically tilted raised shorelines of Late Devensian age, sloping down towards N25°E, at progressively lower gradients between 0.57 and 0.15 m/km. The shorelines were formed in close association with a westward- and southward-receding ice margin and the shoreline sequence suggests that rates of ice margin retreat were most rapid where the ice terminated in the sea.     

Seafloor glacial features reveal the extent and decay of the last British Ice Sheet,east of Scotland

Three‐dimensional (3D) seismic datasets, 2D seismic reflection profiles and shallow cores provide insights into the geometry and composition of glacial features on the continental shelf, offshore eastern Scotland (58° N, 1–2° W). The relic features are related to the activity of the last British Ice Sheet (BIS) in the Outer Moray Firth. A landsystem assemblage consisting of four types of subglacial and ice marginal morphology is mapped at the seafloor. The assemblage comprises: (i) large seabed banks (interpreted as end moraines), coeval with the Bosies Bank moraine; (ii) morainic ridges (hummocky, push and end moraine) formed beneath, and at the margins of the ice sheet; (iii) an incised valley (a subglacial meltwater channel), recording meltwater drainage beneath former ice sheets; and (iv) elongate ridges and grooves (subglacial bedforms) overprinted by transverse ridges (grounding line moraines). The bedforms suggest that fast‐flowing grounded ice advanced eastward of the previously proposed terminus of the offshore Late Weichselian BIS, increasing the size and extent of the ice sheet beyond traditional limits. Complex moraine formation at the margins of less active ice characterised subsequent retreat, with periodic stillstands and readvances. Observations are consistent with interpretations of a dynamic and oscillating ice margin during BIS deglaciation, and with an extensive ice sheet in the North Sea basin at the Last Glacial Maximum. Final ice margin retreat was rapid, manifested in stagnant ice topography, which aided preservation of the landsystem record. Copyright © 2008 John Wiley & Sons, Ltd.     

Global meltwater discharge and the deglacial sea-level record from northwest Scotland

Quantitative models of Earth–ice-sheet–ocean interactions predict that periods of rapid eustatic sea-level rise, indicating enhanced meltwater discharge to the oceans, should be manifest in the relative sea-level histories from sites within the limits of Late Devensian ice sheets. Analysis of a record of relative sea-level change for the last 16000 calendar years from Northwest Scotland constrains the magnitude and timing of two major pulses of meltwater, ca. 14000 and ca. 11300 cal. yr BP, inferred from coral records. The ca. 14000 cal. yr BP event saw a temporary doubling of the flux of meltwater, but existence of the second major event at ca. 11300 cal. yr BP is not supported by the data from northwest Scotland. Copyright © 1999 John Wiley & Sons, Ltd.     

Identification and significance of ice-flow-transverse subglacial ridges (Rogen moraines) in northern central Ireland

In the Omagh Basin, north central Ireland, subglacial diamict ridges lie transverse to southwestward Late Devensian (ca. 23–13 ka) ice flow. These ridges (0.5–2.5 km long, 100–450 m wide, 15–35 m high), are similar morphologically to Rogen moraines, which have not been described previously from the British Isles. The crests of some transverse ridges are streamlined, cross-cut or overprinted by drumlins, whereas other ridges are unmodified and were not affected by later drumlinisation. At Kilskeery, west–east trending eskers overlying unmodified transverse ridges post-date drumlinisation (17–14 ¹⁴C ka). Esker formation shows that the subglacial thermal regime changed from cold-based, favouring bedform preservation, to warm-based with meltwater flowing through enclosed subglacial channels. Patterns of flow-transverse-ridges and spatial variations in the degree of bedform modification record dynamic changes in regional subglacial environments during the last deglacial cycle. This ice-mass variability cannot be reconciled with current Irish glacial models, which are based on immobile ice centres and ordered stages of ice retreat. In a wider context, these changes in bedform patterns and basal ice regimes have a similar signature to millennial-scale ice-mass oscillations recorded by dated proxy evidence elsewhere in the amphi-North Atlantic. © 1997 John Wiley & Sons, Ltd.     

Hydrofracturing in response to the development of an overpressurised subglacial meltwater system during drumlin formation: an example from Anglesey,NW Wales

This paper presents the results of a detailed study of a complex hydrofracture system and host diamictons exposed within a longitudinal section through an elongate drumlin located to the west of Cemlyn Bay, Anglesey, NW Wales. This complex, laterally extensive sand, silt and clay filled hydrofracture system was active over a prolonged period and is thought to have developed beneath the Late Devensian (Weichselian) Irish Sea Ice Stream as it overrode this part of NW Anglesey. The sediment-fill to the hydrofracture system is deformed with kinematic indicators (folds, thrusts, augen) recording a SW-directed sense of shear, consistent with the regional ice flow direction across this part of the island. The lack of any geomorphological evidence for active retreat of the Irish Sea ice across Anglesey has led to the conclusion that hydrofracturing at the Cemlyn Bay site occurred within the bed of the Irish Sea Ice Stream whilst this relatively faster flowing corridor of ice was actively overriding the island. Shear imposed by the overriding ice led to the development of a subglacial shear zone which facilitated the propagation of the hydrofracture system with the laterally extensive feeder sills occurring parallel to Y-type Riedel shears. Although a subglacial setting beneath the active Irish Sea Ice Stream can be argued for the Cemlyn Bay hydrofracture system, its relationship to the formation of the ‘host’ drumlin remains uncertain. However, evidence presented here suggests that hydrofracturing may have occurred during the later stages or post landform development in response to the migration of overpressurised meltwater within the bed of the Irish Sea ice; possibly accompanying the local thinning and shutdown of the Irish Sea Ice Stream on Anglesey.     

Glacial and paraglacial history of the Troutbeck Valley,Cumbria, UK: integrating airborne LiDAR,multibeam bathymetry,and geological field mapping

High resolution airborne LiDAR (light detection and ranging) and multibeam bathymetry data, supplemented by geomorphological and geological field mapping are used to derive the glacial and post-glacial history of Troutbeck Valley (English Lake District) at a catchment scale. The results inform wider regional and ice sheet wide glacial reconstructions and demonstrate the effectiveness of an integrated approach combining geomorphological and sedimentological signatures with remote sensing. The holistic catchment approach is used to reconstruct palaeo-ice flow and behaviour of a small part of the last British and Irish Ice Sheet, identifying a series of depositional environments that accompanied both ice advance, ice retreat and post-glacial deposition within the Lake District. Drumlins are mapped in the lower catchment and show multiple regional (wider-extent) ice flow events and a sedimentology consistent with deposition by lodgement processes during the Main Late Devensian Stadial. Other subglacial deposits include till sequences formed under variable basal conditions beneath an advancing ice mass. Retreat features include a suite of recessional moraines formed by still-stands or small readvances of an outlet glacier. Following deglaciation, major sediment redistribution led to formation of a large fan delta via paraglacial and post-glacial fluvial sedimentation. This study indicates that an integrated approach, using geomorphology, sedimentology and remote sensing on a catchment scale, is capable of deriving a more in-depth understanding of regional ice sheet reconstructions and highlights the complexity of palaeo-ice sheet dynamics at a range of spatial scales.