The possibility of a continuous, kilometre-thick Arctic Ocean ice shelf in the geological past has long intrigued scientists. Yet, fundamental questions surrounding the architecture, timing, and oceanic and climatic consequences of such an ice shelf remain unresolved. A pan-Arctic glaciation model has been inferred primarily from glacial landforms identified on seafloor bathymetric highs and continental shelves, as well as from geochemical proxies found in marine sediment cores.

Subsequent chronological analyses of sediment cores from these eroded regions have suggested that this pan-Arctic Ocean ice shelf developed during Marine Isotope Stage (MIS) 6, approximately 140,000 to 160,000 years ago. In contrast, more recent evidence from the eastern Fram Strait suggests the persistence of marginal sea-ice conditions and recurrent phytoplankton spring blooms across several glacial-interglacial cycles over the last 750,000 years. Nevertheless, an exception appears to occur during MIS 16, a glacial interval between ~670,000 and 620,000 years ago that remains relatively understudied in the Arctic Ocean. During this period, biomarkers indicative of sea ice and primary productivity, and planktic foraminifera are either absent or occur in extremely low concentrations in sediment cores from both the Arctic-Atlantic Gateway and the Nordic Seas. Although the full spatial extent of glacial ice during MIS 16 remains uncertain, it is thought to have rivalled that of the Last Glacial Maximum (LGM) in terms of ice volume. In this study, we present new geomorphological evidence supported by sediment core chronologies for significant Greenland ice sheet expansion during the end of the Mid Pleistocene Transitoin (MPT). The discovery of record-deep ploughmarks, in combination with a grounding zone wedge (GZW) at approximately 800 meters water depth on the Morris Jesup Rise, northeast Greenland, suggests that the Greenland/Innuitian Ice Sheet grew sufficiently to form an ice shelf extending into the central Arctic Ocean – implying an "Antarctification" of Greenland during this extreme glacial phase.

How to cite: Knies, J., Patton, H., Giertzuch, P.-L., and De Schepper, S. and the i2B Arctic Ocean Expedition 2025 Science Party: New evidence for Greenland ice sheet expansion beyond its present shelf break during the Mid-Pleistocene Transition  , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3417, https://doi.org/10.5194/egusphere-egu26-3417, 2026.

Many tens of ice rises exist at the marine margins of the Antarctic Ice Sheet.  Isle-type ice rises in particular are those where an ice shelf is pinned to an underlying submarine bank.  Recent and ongoing studies show that Ross Bank, on the middle continental shelf of central Ross Sea, was the former site of an important Ross Ice Shelf ice rise during the advance and retreat of the West Antarctic Ice Sheet (WAIS) in the last glacial cycle.  Ross Bank is a broad and anomalously shallow water platform whose crest rises to 150 m water depth. Despite its importance as a buttressing site, little is known about how, when and why such submarine banks formed. Here, we use a grid of seismic data acquired during expedition NBP2301/2 to reconstruct how Ross Bank morphology evolved.  Our seismic-based correlations and mapping show that Ross Bank overlies the western flank of the Central High, a large basement horst created during the rifting of Ross Sea.  Seismic correlation to lithologic and chronologic control at IODP expedition 374 sites U1521 and U1522 indicates that thick grounding zone wedges were deposited at the site of Ross Bank during the early Miocene.  Intermittent advance of erosive ice streams deeply eroded those wedges and produced approximately 400 meters of relief at Ross Bank prior to the middle Miocene.  The complete absence of middle Miocene strata at Ross Bank suggests significant intervals of subglacial erosion associated with glacial stages of the Middle Miocene Shift.  In the time since, relatively minor aggradation on the crest of Ross Bank occurred during parts of the late Miocene, Pliocene and Pleistocene. Our analyses make the case that a shallow submarine area existed at Ross Bank since the middle Miocene.  The bank would have been the site of ice rises that influenced the advance and retreat of the WAIS in central Ross Sea over the past 14 Myr.

How to cite: Weber, W. and Bart, P.: The case for Ross Bank ice rises since the middle Miocene, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15366, https://doi.org/10.5194/egusphere-egu26-15366, 2026.

The East Antarctic Ice Sheet (EAIS) contribution for future global sea level rise and climate change is source of uncertainty, and it appears essential to reconstruct its past fluctuations. Previous works reveal geomorphic and chronological evidence that the ice sheet extended to the continental shelf break during LGM (Last Glacial Maximum; ~20 ka). However, still little is known about its response to the major climate and oceanic transitions following the LGM. In this study, we reconstruct (1) a chronology of ice-sheet fluctuations, (2) ice-sheet past erosion efficiency and (3) ice-sheet thinning during the late-Pleistocene to Holocene time-period, in Terre Adélie (East Antarctica). Newly obtained exposure ages for coupled ¹⁰Be-²⁶Al support a scenario of glacial fluctuations at global, regional and local scales. Inland nunataks reveal some long-term exposure with apparent exposure ages ~150 ka, while coastal areas record a past ice-sheet thinning after ~20 ka. Ages measured on erratic boulders of Archipel Pointe Géologie record the final episode of a regional deglaciation around ~15 ka. Slightly inland, in Lacroix sector, erratic boulders record a more recent local ice-sheet oscillations around ~1.5 ka. In contrast, exposure ages obtained on glacially-polished bedrock are characterised by spatially-variable inheritance, suggesting that past ice sheet retreat history is characterised by variations in erosion efficiency. Finally, our results also suggest some potential previous geomorphological inheritance from the hot Pliocene phase.

How to cite: Rolland, Y., Péan, M., Valla, P., Duclaux, G., Braucher, R., Jomelli, V., Favier, V., Schimmelpfennig, I., Crosta, X., Etourneau, J., and Louis, M.: Reconstructing Plio-Quaternary fluctuations of the East Antarctic Ice Sheet in Terre Adélie inferred from cosmogenic nuclides (10Be-26Al) in glacially-polished bedrock, morainic boulders and nunataks , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10117, https://doi.org/10.5194/egusphere-egu26-10117, 2026.

Reconstructions of Antarctica's past ice-sheet evolution remain poorly constrained due to sparse, spatially discontinuous proxies, limiting accurate projections of its future sea-level contribution. Here we present a novel isochronally-constrained reconstruction of Dronning Maud Land (DML), East Antarctica spanning the last interglacial-glacial cycle (~130 kyr), integrating extensive radar-derived internal reflection horizons (IRHs) with PISM ice-sheet simulations.

IRHs preserve continuous records of past accumulation, flow, and basal conditions, providing unprecedented spatiotemporal constraints for model validation. Our ensemble simulations indicate that DML’s sea-level potential change between interglacial and glacial states is comparable to, and likely larger than, the contribution of all modern mountain glaciers, and show that variations in geothermal flux alone can substantially alter sea-level projections. These results provide physical modelling context of East Antarctica's ice history, reveal DML's role in Last Interglacial sea-level rise, and highlight persistent parameterization uncertainties limiting future projections.

How to cite: Višnjević, V., Bodart, J., Hermant, A., Spezia, E., Wirths, C., and Sutter, J.: Modelling the evolution of Dronning Maud Land, Antarctica across the last interglacial-glacial cycle – insights from isochrone modelling., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11727, https://doi.org/10.5194/egusphere-egu26-11727, 2026.

GLAC3 is the first history matching of every last glacial cycle ice sheet. It therefore includes North American, Greenlandic, Icelandic,
Eurasian, Tibetan, Patagonian, and Antarctic components. Instead of determining a non-robust "optimal" chronology, history matching aims
to "bound reality" with robust assessment of both proxy data and model (both parametric and structural) uncertainties. For the four major ice
sheets, this entails Bayesian artificial neural network emulation of the glaciological model predictions to enable adequate Markov Chain
Monte Carlo sampling of chronologies. The history matching is against a large set of geophysical (such as relative sea level and marine
limit), geological (cosmogenic exposure and C14 ages), and glaciological (such as present-day ice surface velocity) constraints.

Aside from being a product of history matching, GLAC3 has two additional unique features. Firstly, it is the only available
deglacial, let alone full glacial cycle, global set of chronologies from glaciological modelling, using the Glacial Systems Model
(GSM) with hybrid shallow ice and shallow shelf ice dynamic. This enables physical resolution of ice sheets, ice streams, ice shelves,
and grounding line migration. As such, GLAC3 is subject to glaciological constraints such as borehole temperature profiles that
non-glaciological reconstructions can't resolve. Secondly, the glaciologically modelling is self-consistently coupled with full
visco-elastic glacio-isostatic adjustment enabling joint history matching of ice history and regional earth viscosity.

The presentation will focus on the relative phasing of each ice sheet, rates of mass gain and loss, and rates of ice margin migration. This
will be compared against both far-field relative sea level records as well as the results of fully coupled ice and climate modelling of the
last glacial cycle with LCice (LOVECLIM + GSM).

How to cite: Tarasov, L., Dalton, A., Dyke, A., Geng, M., Goffin, A., Hughes, A., Lecavalier, B., Mangerud, J., Milne, G., Svendsen, J.-I., and Woodroffe, S.: GLAC3 rates and phasing: the first joint history matching of global last glacial cycle ice sheet evolution and regional earth rheology, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15518, https://doi.org/10.5194/egusphere-egu26-15518, 2026.

How to cite: Romé, Y., Gregoire, L., Gandy, N., Patterson, V., and Ely, J.: Using reconstructed ice streams to calibrate a coupled climate-ice-sheet model of the North American Ice Sheet Complex during the Last Glacial Maximum , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20495, https://doi.org/10.5194/egusphere-egu26-20495, 2026.

The nature of the subglacial environment is a key part of glacier dynamics. Studies from modern glaciers have revealed there is a continuum in subglacial fluvial behaviour associated with a soft-bed, from channelised to distributed. How is this continuum preserved within the sedimentary record and what is the relationship between fluvioglacial sediments and flutes?  Classically eskers are associated with channelized drainage, whilst the sedimentary remains of ‘canals’, ‘subglacial meltwater corridors’ and murtoos may reflect the distributed system. Stratified lenses within till are common and have been given numerous interpretations, either reflecting preglacial sediments that have been incorporated into the till by deformation, or penecontemporaneous sedimentation with the till. We use data from instrumented modern glaciers and Quaternary sections to illustrate the nature and rate of subglacial behaviour associated with soft-bedded glaciers.

How to cite: Hart, J. and Martinez, K.: Soft-bed distributed subglacial sedimentology, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9543, https://doi.org/10.5194/egusphere-egu26-9543, 2026.

Understanding temperature variability during the Holocene is critical for constraining baselines of natural climate variability. Temperate mountain glacier extent is limited most significantly by summer air temperature, thus geological records of past glacier length changes represent a useful proxy for this climatic variable. Iceland’s maritime glaciers with their high sensitivity to temperature and precipitation changes serve as robust indicators of climate variability in the North Atlantic region. Previous reconstructions of Iceland’s Holocene glacier and climate history have relied primarily on marine sediment cores, terrestrial geomorphological evidence, and glaciological modelling. These proxies highlight a correlation between glacier fluctuations and regional climate variability and suggest notable glacier retreats during early and mid-Holocene warm periods.

Here, we present cosmogenic chlorine-36 measurements from four outlet glaciers of the Vatnajöküll ice cap in Iceland that test and further constrain the occurrence of past glacier minima during the Holocene. Unlike the more commonly used method of cosmogenic surface exposure dating of moraines, which constrains the timing of past glacier advances, our application targets the remnant cosmogenic signals of prehistoric exposure events preserved in freshly exposed proglacial surfaces. Our data thus tests for the occurrence and constrains the duration of past glacier retreat events and, thereby, warmer times during the Holocene. Our results support the hypothesis that Icelandic glaciers were smaller than present for several millennia during the Holocene and when combined with existing datasets of Icelandic climate, our new results allow us to reconstruct both glacier advance and retreat through the Holocene.

How to cite: de Campo, A., Eaves, S., Norton, K., Wilcken, K., Fülöp, R.-H., Simon, K., Silvia, C., Lane, T., and Jackson, M.: Cosmogenic chlorine-36 constraints on Holocene glacier change in Iceland, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1360, https://doi.org/10.5194/egusphere-egu26-1360, 2026.

Reconstructing the precise timing and geometry of the British-Irish Ice Sheet (BIIS) is critical for understanding the sensitivity of the North Atlantic climate system to abrupt perturbations. We present preliminary results from a cosmogenic beryllium-10 (¹⁰Be) surface-exposure chronology of glacial deposits in the Gaddagh valley, situated on the northern flank of the McGillycuddy’s Reeks, southwest Ireland. Our geomorphological and chronological transect reveals a detailed history of deglaciation and ice-margin fluctuations since the Late Pleistocene.

Initial results indicate that high-elevation areas (300–350 m asl) adjacent to the main valley were ice-free by ~28 ka (n=2), suggesting an earlier onset of local thinning than previously modelled. The prominent "Hag’s Tooth Moraine”, the primary geomorphological feature in the valley, appears to represent a culmination during the Last Glacial Maximum (LGM). Following this peak, the deposition of a barely preserved subdued moraine impounded Loch Callee at ~19 ka (n=3), marking a significant phase of ice retreat at the onset of Termination 1. The final pulse of glacial activity is recorded 200 m higher in the catchment by a complex of five latero-frontal moraines. These landforms mark the former extent of a small cirque glacier, with the final abandonment of these positions occurring at ~12.7 ka (n=3).

Thus far, our findings implicate the following. First, the data do not support a complete ice cover over the McGillycuddy’s Reeks during the LGM as previously proposed; instead, we suggest that ice was topographically restricted to the main valleys, with the front of the Gaddah glacier not below 150 m asl. Second, our chronology indicates that terminal deglaciation occurred during a period traditionally associated with relatively cold climate conditions. This pattern of glacier recession during inferred year-round cold climate aligns with recent ¹⁰Be chronologies from Scotland (Bromley et al., 2018, 2023), central East Greenland (Kelly et al., 2025), southernmost Greenland (Carlson et al., 2021) and Norway (Putnam et al., 2023; Wittmeier et al., 2020), which demonstrate glacier shrinkage during the Younger Dryas. These results contribute to the ongoing discussion about glacier extension in the area and the evolving paradigm of North Atlantic climate dynamics, emphasizing the role of summer temperature as the primary driver of glacial mass balance during millennial-scale stadials.

How to cite: Rodriguez, P. and Bromley, G.: Lateglacial deglaciation of the McGillycuddy’s Reeks, SW Ireland through 10Be surface-exposure dating of glacial deposits in the Gaddah Valley: Implications for late glacial climate variability., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15730, https://doi.org/10.5194/egusphere-egu26-15730, 2026.

The west-central Keewatin region of northern Canada preserves a rich record of former ice sheets and their impact on the landscape. The diverse assemblage of glacial landforms in the region reflects spatial variations in glacial modification driven by changes in basal thermal regime, subglacial hydrology, and ice-flow dynamics, all of which are key to reconstructing the history and behaviour of palaeo-ice sheets. Resolving how these landforms relate to changes in basal regime and glacial modification requires integrated datasets such as geomorphological mapping and to provide the robust reconstructions needed for climate and ice-sheet models.

Our work aims to provide both a qualitative and quantitative assessment of glacial landscape modification in the west-central Keewatin region of the Northwest Territories and mainland Nunavut using two independent proxies: geomorphic mapping and cosmogenic nuclide concentrations. We used the ArcticDEM and Landsat 8 imagery to remotely map This new inventory of landforms, integrated with existing mapping, provides a qualitative assessment of glacial landsystems and landscape modification across the Keewatin region. As a quantitative proxy for glacial modification from the last glacial period(s), we collected 10 bedrock and 7 boulder samples for cosmogenic ¹⁰Be measurement along a north-south transect east of Dubawnt Lake, Nunavut. The sample transect was informed by glacial geomorphic mapping and was selected to test field-based predictions of the degree of landscape modification from the previous glaciation(s). The northern portion of the transect contains high concentrations of streamlined landforms associated with the onset zone of the Dubawnt Ice stream, inferred to be a region of high glacial modification. In contrast, the southern end of the transect contains lower concentrations of streamlined features, flow sets with contrasting orientations, and cross-cutting striations, suggesting a higher degree of landscape preservation during the last glaciation(s). Preliminary ¹⁰Be results broadly confirm our initial assessment of glacial modification along our transect, revealing slightly higher concentrations of ¹⁰Be in the south (less modification) and decreasing ¹⁰Be concentrations towards the north (more modification). Both bedrock and boulder samples follow this trend, however, our results show that in both low- and high-modification landsystems, some samples retain significant nuclide inheritance, including some boulders which suggests transport from a less modified landscape. Combining qualitative and quantitative approaches to evaluate glacial modification associated with specific landform assemblages informs our understanding of the basal thermal conditions of palaeo-ice sheets, the distribution of which informs our understanding of ice sheet evolution through space and time. Furthermore, the identification of streamlined features into palaeo-flow sets supports potential mineral exploration by helping to determine glacial transport directions and dispersal patterns. However, our results show the concentrations of cosmogenic nuclides vary within individual landsystems, suggesting that glacial modification varied through time and can be influenced by multiple factors (e.g., subglacial thermal conditions, topography, glacio-isostatic adjustment, lake development) that remain to be quantified.  

How to cite: Crowell, C., Kelley, S., Brouard, E., Campbell, J., and Gosse, J.: Using digital mapping and cosmogenic 10Be to assess glacial landscape modification in west-central Keewatin, Arctic Canada , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-822, https://doi.org/10.5194/egusphere-egu26-822, 2026.

Fjord landscapes along the margins of past and present ice sheets testify to the significant long-term erosive power of large outlet glaciers. Yet, our understanding of the rates and processes of subglacial erosion and sediment transport beneath ice sheets remains incomplete. Quantifying these processes is crucial for reconstructing past ice dynamics, estimating sediment fluxes to the ocean, and understanding long-term landscape evolution.

Greenland’s narrow, steep-sided fjords act as natural sediment traps, preserving erosion products delivered by large outlet glaciers during deglaciation. These fjord sediments constitute a valuable constraint on past erosion rates and glacial sediment fluxes when combined with ice catchment areas and retreat histories in a source-to-sink framework. However, most Greenlandic fjords remain unmapped in terms of sediment thickness because sediment cores rarely penetrate deeply and seismic data acquisition is sparse. In contrast, accurate bathymetric data are increasingly available for many fjords. We use a geomorphological approach to estimate sediment infill volumes based on fjord cross-sectional profiles, where deviations from the expected U-shape and the slope of the sidewalls are used to infer sediment thickness.

We quantify fjord infill volumes for several fjords and use these to estimate average catchment-wide erosion rates. The timing of deposition (starting when the ice retreated into the fjord) is constrained by available deglaciation models. To further explore the temporal and spatial variability of subglacial erosion, we employ a coupled ice-flow and erosion model (iSOSIA), driven by paleoclimate forcing, to simulate erosion beneath marine-terminating outlet glaciers during the last deglaciation (~21–0 ka BP). Modeled sediment outputs are compared with our estimates of sediment volumes and accumulation rates from sediment cores to calibrate the model erosion parameters.

Our results indicate that average deglacial erosion rates are largely independent of catchment size but vary significantly through time and space within ice-sheet catchments. Rates can exceed 10 mm yr⁻¹ for topographically steered, fast-flowing outlet glaciers, while much lower rates (<0.1 mm yr⁻¹) occur in slower-flowing interior regions with slow-moving ice. Quantifying and linking offshore sediment volumes with numerical modeling provides an opportunity to constrain subglacial erosion rates, sediment transport and ice-sheet reconstructions. This work demonstrates the value of integrating glaciological modeling with marine sediment archives to refine erosion estimates and improve predictions of future sediment fluxes under continued ice-sheet retreat.

How to cite: Damsgård, J., Brand, C., Jungdal-Olesen, G., and Pedersen, V.: Constraining subglacial erosion in Greenland using estimates of fjord sediment volumes and ice-flow modeling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16822, https://doi.org/10.5194/egusphere-egu26-16822, 2026.

Glacially derived, marine sediments preserve a record of the timing, extent, and dynamics of shelf glaciation. In addition, these deposits can provide constraints on glacial erosion rates and offer insights into landscape evolution. However, in Greenland, the total offshore volume of glacially derived sediments remains poorly constrained due to an uneven distribution of offshore seismic surveys and a lack of dating constraints. To address this, we present a first quantification of Quaternary glacial sediment thicknesses around Greenland, combining interpretations of available marine seismic data with age constraints where scientific boreholes are available and a neural network approach. We train the neural network using the seismic-derived thicknesses, along with several parameters related to glacial and geomorphological features. This approach allows us to predict Quaternary sediment thicknesses in regions with sparse data coverage, thereby constraining the total volumes of deposition. Our estimates reveal regional variations in glacial deposition volumes and sediment thicknesses around Greenland. On the southern and parts of the northern Greenlandic continental slope, Quaternary sediments are thin, whereas in west and east Greenland, larger sediment deposits have led to a greater shelf progradation throughout the Quaternary. These patterns demonstrate a diverse influence of (paleo-)climatic, oceanographic, and orographic processes on glacial dynamics and the source-to-sink sediment transport. Finally, we compare our estimates of Quaternary offshore deposition with estimates of onshore glacial erosion inferred from paleo-topographic reconstructions and erosion potentials of the present ice sheet, based on ice sliding velocities. This provides insights into the temporal and spatial variability of erosion around Greenland, advancing our understanding of the long-term landscape evolution in glaciated regions.

How to cite: Brand, C., Elger, J., Andresen, K. J., Hansen, T. M., Poulsen, V. S., Pérez, L. F., Fox, M., Böttner, C., Knutz, P., Damsgård, J. F., and Pedersen, V. K.: From source to sink: Quantifying Quaternary erosion from offshore deposits associated with the Greenland Ice Sheet, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12234, https://doi.org/10.5194/egusphere-egu26-12234, 2026.

The onset and potentially time-transgressive latitudinal development of Northern Hemisphere glaciations during the Plio-Quaternary represents a key component of global late Cenozoic climate dynamics. The timing of the earliest Alpine glaciations has been debated since the pioneering work of A. Penck and E. Brückner at the beginning of the 20^th century. Over the past three decades, cosmogenic nuclide burial dating has provided absolute ages on glacial and fluvioglacial sedimentary deposits in the Alpine forelands, progressively refining the chronology of early glaciations as methodological advances have emerged and as the number of analyzed samples has increased. Recent syntheses from the northern Alpine foreland (Deckenschotter) and the Ivrea amphitheater indicate that piedmont glacier lobes developed between 1.2 and 0.8 Ma, suggesting that the first extensive Alpine-wide glaciations occurred during the Mid-Pleistocene Transition. However, reconstructions based solely on surface deposits are strongly affected by preservation biases, as repeated glaciations may have eroded older sedimentary archives. As a result, Early Pleistocene surface records may have been largely removed by subsequent, more extensive glaciations.

Karst systems provide an alternative archive for early glaciations. During glacial periods, glaciers in contact with karst conduits inject detrital material (allochthonous or autochthonous) into subsurface voids, where sediments can be preserved for several million years. These buried deposits can be dated using in situ cosmogenic nuclides such as ²⁶Al–¹⁰Be in quartz. Prior to this study, very few geochronological and sedimentological data existed for such ancient glacio-karst deposits (i.e. Early Pleistocene). New ²⁶Al–¹⁰Be burial ages obtained from 20 detrital endokarst sediment samples (sands and pebbles) in the western to central Alps (Vercors, Chartreuse, Haut-Giffre and Bernese Alps), together with a synthesis of existing dating in the central Alps, allow the first spatio-temporal reconstruction of glacial sediment injections into the Alpine karst. Consistent with surface records, the burial ages reveal major glacial sediment injections into the karst around 0.8 Ma, at the end of the Mid-Pleistocene Transition. However, the data also point to a much earlier phase of widespread injections around 2 Ma. These early injections occurred both in high-elevation (>2500 m) headwater karst systems and in peripheral karst networks bordering the major Alpine valleys along the mountain front, demonstrating that widespread early glaciations affected the entire Alpine chain around 2 Ma. Because Alpine valleys were less deeply incised during the Early Pleistocene, glacier geometries differed significantly from those of Middle and Late Pleistocene glaciations, with thinner and potentially less extensive ice bodies. These earliest Alpine glaciations are contemporaneous with major advances of the Eurasian and North American ice sheets, consistent with extensive Northern Hemisphere glaciations at that time, predating the intensification of glaciations initiated at the Mid-Pleistocene Transition. Ultimately, this study highlights the potential of mountain karst systems as long-term archives for reconstructing Quaternary climate transitions.

How to cite: Mai Yung Sen, V., Valla, P., Jaillet, S., Robert, X., Rolland, Y., Borreguero, M., Carcaillet, J., Pons-Branchu, E., Crouzet, C., and Bruguier, O.: Early Alpine glaciations at ca. 2 Ma revealed by 26Al–10Be burial dating of endokarst sediments in the western–central European Alps, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-461, https://doi.org/10.5194/egusphere-egu26-461, 2026.

Reconstructions of Northern Hemisphere ice sheets throughout the Quaternary are central to interpreting past variations in sea level, ocean-atmospheric circulation, and climate. Yet, terrestrial records of the earliest glaciations are fragmentary and anchored principally to relative chronostratigraphic frameworks, limiting direct comparison with more continuous marine archives. Here, we present new dating and sedimentary provenance constraints, motivating reassessment of the early history of the Eurasian Ice Sheet (EIS) and its role within the evolving Pleistocene climate system.

Cosmogenic ²⁶Al-¹⁰Be burial dating of key glacigenic deposits from northwest and central Europe reveals that extensive EIS advances occurred repeatedly during the Early Pleistocene, beginning as early as ~2.35 million years ago (Ma), and substantially predating the traditionally inferred onset of lowland glaciation during marine isotope stages (MIS) 16–12 (~0.65–0.45 Ma). Detrital zircon U-Pb fingerprinting of these deposits indicates that successive EIS advances transported sediment from the Fennoscandian Shield into the North Sea Basin and the North European Plain, implying that ice flow pathways through the Baltic Depression were established already in the Early Pleistocene and the Baltic (Eridanos) River System had terminated by at least ~1.5 Ma.

Our revised chronologies highlight that the most extensive EIS configurations formed prior to the Middle Pleistocene Transition, and within the context of apparent low-amplitude glacial cycles of the ‘41-kyr world.’ When integrated with independent geochronologic evidence from North America, these findings (within uncertainties) point to broadly synchronous Early–Middle Pleistocene expansions of the major Northern Hemisphere ice sheets. Such early attainment of continental-scale ice sheets may help to reconcile available terrestrial evidence with emerging reconstructions of significant glacial sea-level lowstands prior to the dominance of ~100-thousand year glacial cycles.

More generally, this synthesis calls for re-examination of long-standing European Quaternary stratigraphic frameworks and suggests that Eurasian glaciation may have played an important role in reorganizing continental drainage, modulating freshwater delivery to the North Atlantic, and influencing ocean-atmospheric circulation throughout the Early–Middle Pleistocene.

How to cite: Wagner, K., Ylä-Mella, L., Margold, M., Faurschou Knudsen, M., and D. Jansen, J.: Two million years of the Eurasian Ice Sheet, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14737, https://doi.org/10.5194/egusphere-egu26-14737, 2026.