Postglacial emergence and Late Quaternary glaciation on northern Novaya Zemlya, Arctic Russia

Recent observations on postglacial emergence and past glacier extent for one of the least accessible areas in the Arctic, northern Novaya Zemlya are here united. The postglacial marine limit formed 5 to 6 ka is registered on the east and west coasts of the north island at 10 ± 1 and 18 ± 2 m aht, respectively. This modest and late isostatic response along with deglacial ages of >9.2 ka on adjacent marine cores from the northern Barents Sea indicate either early (>13 ka) deglaciation or modest ice sheet loading (<1500 m thick ice sheet) of Novaya Zemlya. Older and higher (up to 50 m aht) raised beaches were identified beneath a discontinuous glacial drift. Shells from the drift and underlying sublittoral sediments yield minimum limiting ¹⁴C ages of 26 to 30 ka on an earlier deglacial event(s). The only moraines identified are within 4 km of present glacier margins and reflect at least three neoglacial advances in the past 2.4 ka.     

The last glaciation and relative sea level history of Northwest Ellesmere Island,Canadian high arctic

Philips Inlet and Wootton Peninsula are located at 82°N and 85°W on the northwest coast of Ellesmere Island and are composed of three bedrock controlled zones: (1) 900 m undulating plateau dissected by fiords; (2) a deeply fretted cirque terrain >1200m; (3) a 300m plateau bounded by coastal cliffs. Each zone contains different glacier morphologies and these control glacigenic sediment and landform assemblages. The extent of the last glaciation is mapped using the distribution of moraines, kames, meltwater channels and glacimarine sediments. Glaciers advanced on average <10 km from their present margins and many piedmont lobes coalesced and floated in the sea. Morainal banks were deposited at the grounding lines of floating glaciers, and where debris-charged basal ice occurred, subaqueous fans were deposited upon deglaciation. Marine shells dating 20.2 ka BP (<2km from present ice margin) and 14.9ka BP (from a morainal bank) document full glacial marine fauna. Thirty-three radiocarbon dates document glacier retreat patterns and are used to reconstruct the postglacial sea level history (glacioisostatic rebound pattern). An equidistant shoreline diagram is constructed using the 8.5ka BP shoreline as a guide. Tilts from 0.73-0.85m/km are calculated for this shoreline. Using two firm control points and tilts from elsewhere on northern Ellesmere Island, the 10.1 ka BP (full glacial) marine limit descends from 117m as at the fiord heads to 63 m asl at the north coast. Deglaciation started with a pronounced calving phase throughout the field area between 10.1 and 7.8ka BP. This chronology is similar to that from northeast Ellesmere Island and attests to an early Holocene warming trend recorded in high arctic ice cores. A maximum lag of 2.1 ka exists between the field area and locations to the south of the Grant Land Mountains suggesting differences in glacioclimatic regimes on either side of the mountain range. Persistent reconstructions of all-pervasive ice sheets for the last glaciation of the area are obsolete and should be abandoned.     

Glacial history and marine environmental change during the last interglacial-glacial cycle, western Spitsbergen, Svalbard

Superimposed glacial and marine sediment exposed in coastal cliffs on Brøggerhalvøya, west Spitsbergen, contain four emergence cycles (episodes D, C, B, and A) that are related to glacial-isostatic depression and subsequent recovery of the crust. Tills are found in episodes C and B; in each case glaciation began with an advance of local glaciers, followed by regional glaciation. The marine transgression following episode C deglaciation reached 70 to 80 m above sea level. Glacial-marine and sublittoral sands within episode C contain a diverse and abundant microfauna requiring marine conditions more favorable than during the Holocene. We define this interval as the Leinstranda Interglacial. Based on the fauna, sedimentology and geochronology (radiocarbon, amino acid racemization, and uranium-series disequilibrium) we conclude that the Leinstranda Interglacial occurred during isotope substage 5e. Episode B deglaciation occurred late in isotope stage 5 (c. 70 ± 10 ka ago), and was followed by a marine transgression to about 50 m above sea level. The associated foraminifera, mollusca, and vertebrate fauna require seasonally ice-free conditions similar to those of the Holocene, but less ameliorated than during the Leinstranda Interglacial. A significant influx of Atlantic water into the Norwegian Sea, augmented by a local insolation maximum late in isotope stage 5, are required to produce shallow-water conditions similar to those of the Holocene. There is no evidence for major glacial activity during the Middle Weichselian (isotope stages 4 and 3), and we conclude that ice margins were not significantly different from those of the late Weichselian, but the record for this interval is scant. The extent of ice at the Late Weichselian maximum was less than during either of the two preceding episodes (B or C). Late Weichselian deglaciation (episode A) began prior to 13 ka B.P. Oceanic and atmospheric circulation patterns conducive to large-scale glaciation of western Spitsbergen are not well understood, but those patterns that prevailed during isotope stages 4,3, 2, and 1 did not produce a major glacial advance along this coast.     

Late Weichselian glaciation and deglaciation of Forlandsundet area, western Spitsbergen, Svalbard

Late Weichselian glacier limits for the Forlandsundet area, western Spitsbergen are reconstructed from the stratigraphic distribution of tills and deglacial deposits, variations in the altitude of the marine limit, distribution of pre-Late Weichselian raised beach deposits, and the rare occurrence of moraines and striated bedrock. The Late Weichselian glaciation was primarily a local event with fjord outlet-glaciers expanding no more than 15 km beyond their present position; cirque glaciers were similar to their neoglacial limits. A previously reconstructed ice sheet centered over the Barents Shelf had little direct influence on the glaciation of the Forlandsundet area. Glacier retreat began at or prior to 10.5 ka ago and possibly as early as 13 ka ago with fjords mostly, and perhaps rapidly deglaciated by 10 to 9 ka ago.     

Late Quaternary history around Nioghalvfjerdsfjorden and Jøkelbugten, North-East Greenland

Nioghalvfjerdsfjorden in North-East Greenland is at present covered by a floating glacier. Raised marine deposits in the surrounding area contain shells of marine molluscs, bones of marine mammals and pieces of driftwood. A fairly systematic sampling of such material has been conducted, followed by extensive radiocarbon dating. We suggest that the Greenland ice sheet extended onto the shelf offshore North-East Greenland during isotope stage 2, perhaps even reaching the shelf break. During the subsequent recession of the ice sheet, the entrance of Nioghalvfjerdsfjorden had become ice-free by 9.7 cal. ka BP. The recession culminated between 7.7 and 4.5 cal. ka BP, during which time the fjord was glacier-free along its entire 80 km length. No dates younger than 4.5 cal. ka BP are available on marine material from the fjord, and it seems probable that the fjord has been continuously covered by the floating glacier since this time. The maximum glaciation was attained around AD 1900, after which thinning and recession took place. The marine limit increases from c. 40 m above sea level near the present margin of the Inland Ice to c. 65 m above sea level at the outer coast. These figures fit into the regional pattern of the marine limit for areas both to the south and north. The marine fauna comprise two bivalves, Macoma calcarea and Serripes groenlandicus, that may represent a southern element present during the Holocene temperature optimum. Remains of three taxa of southern extralimital terrestrial and limnic plants were dated to 5.1 cal. ka BP, and remains of another extralimital plant were dated to 8.8 and 8.5 cal. ka BP. The known Holocene time ranges of the willow Salix arctica and the lemming Dicrostonyx torquatus have been extended back to 8.8 and 6.4 cal. ka BP, respectively, providing minimum dates for their immigration to Greenland.     

High-resolution paleomagnetic correlation of Middle Weichselian ice-dammed lake sediments in two coastal caves, western Norway

Olahola is a wavecut cave positioned well above the postglacial marine limit. The sediment sequence in the cave can be litho- and magnetostratigraphically correlated with the sequence in the Skjonghelleren cave, 36 km northeast of this locality. Three boulder formations in Olahola represent three ice-free periods (including the Holocene) and two formations of laminated clay represent periods of ice-cover. Paleomagnetic excursions in the laminated clays have been correlated with the Lake Mungo/Mono Lake excursion (28 ka), and with the Laschamp excursion (43 ka), but the resolution of these events is much better in the caves than anywhere else. The paleomagnetic records from Skjonghelleren and Olahola suggest that during the Laschamp excursion at least 0.75–1 m of sediment accumulated in Skjonghelleren before sedimentation started in Olahola, indicating also an earlier ice coverage at Skjonghelleren.     

High-arctic fan delta recording deglaciation and environment disequilibrium

Study of a Holocene fan delta in Adventfjorden, Spitsbergen, provides new insight into the nature of high‐arctic coastal sedimentation and deglaciation dynamics. The fjord‐side, gravelly Gilbert‐type fan delta began to form at the local marine limit c. 10 ka BP, supplied seasonally with sediment by meltwater from a cirque glacier left behind by the retreating Late Weichselian ice sheet. Relative sea level had fallen by 63 m, and the fan delta reached a radius of c. 1 km by 6 ka BP, when the relic glacier eventually melted down and fluvial activity declined. A strong influence of marine processes is recorded by the fan‐delta foreset facies, overlain by alluvium. Supplied with sediment by longshore drift, the fan‐delta front continued to advance at a lower rate, while relative sea level fell further by 5 m and ceased to fall around 5·4 ka BP. The following transgression was countered by longshore sediment supply until 4·7 ka BP, when the delta‐front beach aggraded and a spit platform began to climb onto the delta plain, recording a relative sea‐level rise of 4 m. The subsequent regression was initially non‐depositional, with the relative sea level falling by > 4 m in 200 years, outpacing fluvial supply, and the re‐emerging fan delta being swept by longshore currents. A regressive beach began to form c. 4·3 ka BP, while relative sea level gradually reached its present‐day position. The feeder braided stream was wandering across the delta plain during this time, but incised once the fan‐delta shoreline began to retreat by wave erosion and turned into a receding modern escarpment. The stream has since been adjusting its profile by gradually eroding the pre‐existing alluvium and distributing the coarse sediment supplied from catchment slopes by debrisflows and snow avalanches. Modern snowflows have also spread debris onto the abandoned fan surface. The erosional retreat of the fan delta has been accompanied by lateral shoreline accretion on both its sides. The study has important regional implications and demonstrates that Holocene fan deltas can provide a valuable record of the deglaciation history in high‐arctic terrains, where glacial deposits are scarcely preserved on land.     

Late Weichselian deglacial history of Disko Bugt, West Greenland, and the dynamics of the Jakobshavns Isbrae ice stream

New relative sea-level (RSL) data from Disko Bugt, a large marine embayment in West Greenland, are used to examine the deglacial history of the Jakobshavns Isbrae ice stream. RSL data show rapid deglaciation after 10.3 ka cal. yr BP. Once deglaciation began, a bedrock high in the west of the bay exerted no discernible influence on the deglacial chronology. Following initial rapid retreat, ice stream recession slowed as it approached the eastern shores of the bay. Seabed elevations increase here and the ice stream terminus lingered for several thousand years before retreating into the narrow bedrock-confined Jakobshavns Isfjord. The seabed topography of Disko Bugt includes several deep channels which probably record the former course of the ice stream. Using a simple water depth/calving velocity relationship it is estimated that the maximum calving velocity on deglaciation was c. 4.8 km a^-1. This is less than the present rate (6–7 km a^-1), although ice discharge was two to four times that observed today. Initiation of rapid ice stream retreat was probably caused by ice stream thinning and increased surface melting. A critical point in time was the retreat of the ice stream from shallow continental shelf waters ( c. 400 m) into the deep bedrock trough (>800 m) which marks the entrance to Disko Bugt.     

Chronology and extent of the Lofoten–Vesterålen sector of the Scandinavian Ice Sheet from 26 to 16 cal. ka BP

The interplay between the onshore and offshore areas during the Last Glacial Maximum and the deglaciation of the Scandinavian Ice Sheet is poorly known. In this paper we present new results on the glacial morphology, stratigraphy and chronology of Andøya, and the glacial morphology of the nearby continental shelf off Lofoten–Vesterålen. The results were used to develop a new model for the timing and extent of the Scandinavian Ice Sheet in the study area during the local last glacial maximum (LLGM) (26 to 16 cal. ka BP). We subdivided the LLGM in this area into five glacial events: before 24, c. 23 to 22.2, 22.2 to c. 18.6, 18 to 17.5, and 16.9–16.3 cal. ka BP. The extent of the Scandinavian Ice Sheet during these various events was reconstructed for the shelf areas off Lofoten, Vesterålen and Troms. Icecaps survived in coastal areas of Vesterålen–Lofoten after the shelf was deglaciated and off Andøya ice flowed landwards from the shelf. During the LLGM the relative sea level was stable until 18.5 cal. ka BP, and thereafter there was a sea‐level drop on Andøya. Thus, relative sea level (i.e. a sea level rise) does not seem to be a driving mechanism for ice‐margin retreat in this area but the fall in sea level may have had some importance for the grounding episodes on the banks during deglaciation. The positions of the grounding zone wedges (GZWs) in the troughs are related to the morphology as they are often located where the troughs narrow.     

Chronology and styles of glaciation in an inter‐fjord setting,northwestern Svalbard

Alexanderson, H., Landvik, J. Y. & Ryen, H. T. 2010: Chronology and styles of glaciation in an inter‐fjord setting, northwestern Svalbard. Boreas, 10.1111/j.1502‐3885.2010.00175.x. ISSN 0300‐9483. A 30‐m‐thick sedimentary succession at Leinstranda on the southwestern coast of Brøggerhalvøya, northwestern Svalbard, spans the two last glacial–interglacial cycles and reveals information on glacial dynamics, sea‐level changes and the timing of these events. We investigated the deposits using standard stratigraphical and sedimentological techniques, together with ground‐penetrating radar, and established an absolute chronology based mainly on optically stimulated luminescence dating. We identified facies associations that represent depositional settings related to advancing, overriding and retreating glaciers, marine and littoral conditions and periglacial surfaces. The environmental changes show an approximate cyclicity and reflect glaciations followed by high sea levels and later regression. The luminescence chronology places sea‐level highstands at 185 ± 8 ka, 129 ± 10 ka, 99 ± 8 ka and 36 ± 3 ka. These ages constrain the timing of recorded glaciations at Leinstranda to prior to c. 190 ka, between c. 170 and c. 140 ka (Late Saalian) and between c. 120 ka and c. 110 ka (Early Weichselian). The glaciations include phases with glaciers from three different source areas. There is no positive evidence for either Middle or Late Weichselian glaciations covering the site, but there are hiatuses at those stratigraphic levels. A high bedrock ridge separates Leinstranda from the palaeo‐ice stream in Kongsfjorden, and the deposits at Leinstranda reflect ice‐dynamic conditions related to ice‐sheet evolution in an inter‐fjord area. The environmental information and the absolute chronology derived from our data allow for an improved correlation with the marine record, and for inferences to be made about the interaction between land, ocean and ice during the last glacial–interglacial cycles.     

A Holocene sea‐level curve and revised isobase map based on isolation basins from near the southern tip of Norway

We report a new Holocene relative sea‐level curve based on the stratigraphy in five closely located isolation basins near Lista in southernmost Norway. The results detail the progress and timing of the mid‐Holocene Tapes transgression, the peak of which in this region represents the highest postglacial sea level, as well as the rate of land emergence since then. One additional cored basin is situated above the marine limit. All the basins have bedrock sills that were levelled using a differential GPS. Isolation and ingression boundaries were identified by macrofossil analysis and radiocarbon dated on terrestrial plant remains. In most cases several dates were obtained from each transition. Relative sea level rose with a mean rate of 7 mm a^?1 during the last part of the Tapes transgression 8600?8200 cal. a BP and then gradually slowed to a mean rate of 1 mm a^?1 from 8200?7000 cal. a BP. Mean sea level reached ～5 m higher than the present level when the transgression culminated. Land emergence took place after this, first slowly at a mean rate of 0.4 mm a^?1 until ～3900 cal. a BP before it increased to 2.6 mm between 3900 and 3400 cal. a BP. Since then it has slowly decreased until today and has been ～0.2 mm a^?1 for the last 2000 years. Based on the new curve we present updated Tapes isobases for the region that are displaced by ～20 km in relation to the existing model. From one basin we also report a 5–10 cm thick layer of sorted, sandy gravel, embedded in a more than 5‐m‐thick deposit of homogeneous shallow‐marine mud. The gravel was deposited ～5500 cal. a BP, which is the same age as a tsunami deposit previously mapped in Shetland. As several typical characteristics of tsunami facies deposits are lacking, the origin of the gravel layer remains inconclusive.     

Deglaciation, basin formation and post-glacial climate change from a regional network of sediment core sites in Ohio and eastern Indiana

Many paleoclimate and landscape change studies in the American Midwest have focused on the Late Glacial and early Holocene time periods (~ 16–11 ka), but little work has addressed landscape change in this area between the Last Glacial Maximum and the Late Glacial (~ 22–16 ka). Sediment cores were collected from 29 new lake and bog sites in Ohio and Indiana to address this gap. The basal radiocarbon dates from these cores show that initial ice retreat from the maximal last-glacial ice extent occurred by 22 ka, and numerous sites that are ~ 100 km inside this limit were exposed by 18.9 ka. Post-glacial environmental changes were identified as stratigraphic or biologic changes in select cores. The strongest signal occurs between 18.5 and 14.6 ka. These Midwestern events correspond with evidence to the northeast, suggesting that initial deglaciation of the ice sheet, and ensuing environmental changes, were episodic and rapid. Significantly, these changes predate the onset of the Bølling postglacial warming (14.8 ka) as recorded by the Greenland ice cores. Thus, deglaciation and landscape change around the southern margins of the Laurentide Ice Sheet happened ~ 7 ka before postglacial changes were felt in central Greenland.     

The Late Devensian (<22,000 BP) Irish Sea Basin: The sedimentary record of a collapsed ice sheet margin

The Late Devensian (<20 ka BP) glacial geology of the Irish Sea Basin (4000 km²) is an event stratigraphy recording the entry of marine waters into a glacio-isostatically-depressed basin, and the rapid retreat of the Irish Sea Glacier as a tidewater ice margin. Marine limits occur up to 140 m O.D. Across much of the central basin, the ice margin was uncoupled from its bed exposing a subglacially-scoured topography to glaciomarine processes. The Irish Sea Glacier was a major drainage conduit of the last British Ice Sheet; calving of the marine ice margin resulted in fast flow (surging) of ice streams recorded by drumlin fields around the northern basin margin and tunnel valleys. Rapid evacuation of the basin may have stranded large areas of dead ice in peripheral zones (e.g. Cheshire/Shropshire Lowlands) and initiated the collapse of the ice sheet.Thick wedges of ice-contact glaciomarine sediments were deposited during ice retreat as morainal bank complexes by successive tidewater ice margins stabilized at pinning points around the Irish Sea coast. Where morainal banks occur on the seaward side of drumlin swarms there is a clear sequential relationship between rapid ice loss from calving ice margins, the development of fast flowing ice streams, drumlinization and the pumping of subglacial sediment to tidewater. Raised delta complexes are locally associated with marine limits along the high relief coastal margins of Wales, east central Ireland, and the Lake District. Associated valley infill complexes record downslope resedimentation of heterogenous sediments into the marine environment during ice retreat. Co-eval offshore deposits are represented by well-stratified glaciomarine complexes that infill a subglacially-scoured topography that shows networks of tunnel valleys. Glaciomarine mud drapes occur well to the south of the maximum limit of grounded ice in the basin (e.g. North Devon, Scilly Islands, Southern Ireland). The age of these distal sediments, previously mapped as pre-Devensian tills, is constrained by amino acid ratios.Basin rebound following deglaciation was rapid, with over 100 m recovery in 3 ka, and was followed by a low marine still stand. Peat, accumulating in offshore areas now as much as 55 m below sea level has been drowned by the postglacial eustatic rise in sea level.The glacio-sedimentary model identified in this paper, involving rapid ice retreat and related sedimentation triggered by rising relative sea level, suggests that isotatic downwarping is an important mechanism for deglaciating continental shelves.     

Postglacial emergence and the Tapes transgression, north-central Kola Peninsula, Russia

The history of postglacial emergence on the Murman coast, Kola Peninsula, is reconstructed based on twelve new radiocarbon ages from three marine sections and regional shoreline observations. Two pronounced shore levels are recognized below the Late Weichselian marine limit. The lower shoreline (11 -16 m a.s.l.) is associated with a transgression dated to 6200–6600 BP, correlative to the Tapes transgression on the Norwegian coastline. The upper shoreline (36–47 m a.s.l.) is not yet dated directly but probably correlates to the Main (Younger Dryas) shoreline. Strandline elevations descend eastward along the Murman coast. Observed emergence trends suggest the greatest regional Late Weichselian glacier load over the west-central Kola Peninsula rather than in the southern Barents Sea.     

Advance,deglacial and sea‐level chronology for Foxe Peninsula,Baffin Island,Nunavut

The impact of the Laurentide Ice Sheet (LIS) deglaciation on Northern Hemisphere early Holocene climate can be evaluated only once a detailed chronology of ice history and sea‐level change is established. Foxe Peninsula is ideally situated on the northern boundary of Hudson Strait, and preserves a chronostratigraphy that provides important glaciological insights regarding changes in ice‐sheet position and relative sea level before and after the 8.2 ka cooling event. We utilized a combination of radiocarbon ages, adjusted with a new locally derived ΔR, and terrestrial in‐situ cosmogenic nuclide (TCN) exposure ages to develop a chronology for early‐Holocene events in the northern Hudson Strait. A marine limit at 192 m a.s.l., dated at 8.1–7.9 cal. ka BP, provides the timing of deglaciation following the 8.2 ka event, confirming that ice persisted at least north of Hudson Bay until then. A moraine complex and esker morphosequence, the Foxe Moraine, relates to glaciomarine outwash deltas and beaches at 160 m a.s.l., and is tightly dated at 7.6 cal. ka BP with a combination of shell dates and exposure ages on boulders. The final rapid collapse of Foxe Peninsula ice occurred by 7.1–6.9 cal. ka BP (radiocarbon dates and TCN depth profile age on an outwash delta), which supports the hypothesis that LIS melting contributed to the contemporaneous global sea‐level rise known as the Catastrophic Rise Event 3 (CRE‐3).     

The upper Hawkesbury River, New South Wales, Australia: a Holocene example of an estuarine bayhead delta

Holocene deposits of the Hawkesbury River estuary, located immediately north of Sydney on the New South Wales coast, record the complex interplay between sediment supply and relative sea-level rise within a deeply incised bedrock-confined valley system. The present day Hawkesbury River is interpreted as a wave-dominated estuarine complex, divisible into two broad facies zones: (i) an outer marine-dominated zone extending 6 km upstream from the estuary mouth that is characterized by a large, subtidal sandy flood-tidal delta. Ocean wave energy is partially dissipated by this flood-tidal delta, so that tidal level fluctuations are the predominant marine mechanism operating further landward; (ii) a river-dominated zone that is 103 km long and characterized by a well developed progradational bayhead delta that includes distributary channels, levees, and overbank deposits. This reach of the Hawkesbury River undergoes minor tidal level fluctuations and low fluvial runoff during baseflow conditions, but experiences strong flood flows during major runoff events. Fluvial deposits of the Hawkesbury River occur upstream of this zone. The focus of this paper is the Hawkesbury River bayhead delta. History of deposition within this delta over the last c. 12 ka is interpreted from six continuous cores located along the upper reaches of the Hawkesbury River. Detailed sedimentological analysis of facies, whole-core X-ray analysis of burrow traces and a chronostratigraphic framework derived from 10 C-14 dates reveal four stages of incised-valley infilling in the study area: (1) before 17 ka BP, a 0–1 m thick deposit of coarse-grained fluvial sand and silt was laid down under falling-to-lowstand sea level conditions; (2) from 17 to 6·5 ka BP, a 5–10 m thick deposit composed of fine-grained fluvial sand and silt, muddy bayhead delta and muddy central-basin deposits developed as the incised valley was flooded during eustatic sea-level rise; (3) during early highstand, between 6·5 and 3 ka BP, a 3–8 m thick bed of interbedded muddy central-basin deposits and sandy river flood deposits, formed in association with maximum flooding and progradation of sandy distributary mouth-bar deposits commenced; (4) since 3 ka BP, fluvial deposits have prograded toward the estuary mouth in distributary mouth-bar, interdistributary-bay and bayhead-delta plain environments to produce a 5–15 m thick progradational to aggradational bayhead-delta deposit. At the mouth of the Hawkesbury estuary subaqueous fluvial sands interfinger with and overlie marine sands. The Hawkesbury River bayhead-delta depositional succession provides an example of the potential for significant variation of facies within the estuarine to fluvial segment of incised-valley systems.     

The Weichselian glaciation in Svalbard before 15,000 B.P.*

Th/U dating and radiocarbon dating of 'old' shells are discussed, and amino acid ratios from shells are used as a method of relative-age dating. The Svalbard area has been completely covered by an extensive ice sheet at leats once. New data from Sjuøyane indicate that such glaciation took place in the Early Weichselian. The Middle Weichselian was a period of interstadial conditions. Series of beaches of assumed Middle Weichselian age occur in several places in western Spitsbergen while no such beaches are known in the eastern part of the archipelago. The maximum glaciation in the Late Weichselian is assumed to have taken place about 18,000 B.P. In the western part of Spitsbergen, the Late Weichselian glaciation was limited and local, while the eastern part of the archipelago was covered by an ice sheet. Kongsøya has a pattern of Holocene shoreline displacement which indicates that the centre of this ice sheet was east of kong karts Land.     

Lateglacial to Holocene relative sea‐level changes in the Stykkishólmur area,northern Snæfellsnes,Iceland

Comparatively little research has been undertaken on relative sea‐level (RSL) change in western Iceland. This paper presents the results of diatom, tephrochronological and radiocarbon analyses on six isolation basins and two coastal lowland sediment cores from the Stykkishólmur area, northern Snæfellsnes, western Iceland. The analyses provide a reconstruction of Lateglacial to mid‐Holocene RSL changes in the region. The marine limit is measured to 65–69 m above sea level (asl), with formation being estimated at 13.5 cal ka BP. RSL fall initially occurred rapidly following marine limit formation, until ca. 12.6 cal ka BP, when the rate of RSL fall decreased. RSL fell below present in the Stykkishólmur area during the early Holocene (by ca. 10 cal ka BP). The rates of RSL change noted in the Stykkishólmur area demonstrate lesser ice thicknesses in Snæfellsnes than Vestfirðir during the Younger Dryas, when viewed in the regional context. Consequently, the data provide an insight into patterns of glacio‐isostatic adjustment surrounding Breiðafjörður, a hypothesized major ice stream at the Last Glacial Maximum.     

The last deglaciation of the Franz Victoria Trough, northern Barents Sea

A study of two piston cores and a 3.5 kHz seismic profile from the Franz Victoria Trough provides new stratigraphic, stable isotopic and foraminiferal AMS ¹⁴C data that help constrain the timing of ice-sheet retreat in the northern Barents Sea and the nature of the deglacial marine environment. Silty diamicton at the base of each core, interpreted as till or ice-marginal debris flow, suggests that the Barents ice sheet was grounded at the core sites (470 m water depth). Eight AMS ¹⁴C dates on sediment overlying the diamicton indicate that the ice sheet retreated from both core sites by 12.9 ka and that postglacial sedimentation began 10 ka ago. These dates, combined with a recently published ¹⁴C date from a nearby core, suggest that the Franz Victoria Trough may not have been deglaciated until c . 13 ka, 2000 years later than modeled ice-sheet reconstructions indicate. In the trough, oxygen isotopic ratios in planktonic foraminifera ^N. pachyderma (sinistral) were 0.5–0.750, lower during deglaciation than after, probably as a result of ice-sheet and/or iceberg melting. Foraminiferal assemblages suggest that Atlantic-derived intermediate water may have begun to penetrate the trough c . 13 ka ago.     

Calibrating a glaciological model of the Greenland ice sheet from the Last Glacial Maximum to present-day using field observations of relative sea level and ice extent

We constrain a three-dimensional thermomechanical model of Greenland ice sheet (GrIS) evolution from the Last Glacial Maximum (LGM, 21 ka BP) to the present-day using, primarily, observations of relative sea level (RSL) as well as field data on past ice extent. Our new model (Huy2) fits a majority of the observations and is characterised by a number of key features: (i) the ice sheet had an excess volume (relative to present) of 4.1 m ice-equivalent sea level at the LGM, which increased to reach a maximum value of 4.6 m at 16.5 ka BP; (ii) retreat from the continental shelf was not continuous around the entire margin, as there was a Younger Dryas readvance in some areas. The final episode of marine retreat was rapid and relatively late (c. 12 ka BP), leaving the ice sheet land based by 10 ka BP; (iii) in response to the Holocene Thermal Maximum (HTM) the ice margin retreated behind its present-day position by up to 80 km in the southwest, 20 km in the south and 80 km in a small area of the northeast. As a result of this retreat the modelled ice sheet reaches a minimum extent between 5 and 4 ka BP, which corresponds to a deficit volume (relative to present) of 0.17 m ice-equivalent sea level. Our results suggest that remaining discrepancies between the model and the observations are likely associated with non-Greenland ice load, differences between modelled and observed present-day ice elevation around the margin, lateral variations in Earth structure and/or the pattern of ice margin retreat.