Search

This work was supported by Natural Environment Research Council consortium grant: BRITICE-CHRONO NE/J009768/1. This paper provides a new deglacial chronology for retreat of the Irish Ice Sheet from the continental shelf of western Ireland to the adjoining coastline, a region where the timing and drivers of ice recession have never been fully constrained. Previous work suggests maximum ice‐sheet extent on the outer western continental shelf occurred at ~26–24 cal. ka BP with the initial retreat of the ice marked by the production of grounding‐zone wedges between 23–21.1 cal. ka BP . However, the timing and rate of ice‐sheet retreat from the inner continental shelf to the present coast are largely unknown. This paper reports 31 new terrestrial cosmogenic nuclide (TCN ) ages from erratics and ice‐moulded bedrock and three new optically stimulated luminescence (OSL ) ages on deglacial outwash. The TCN data constrain deglaciation of the near coast (Aran Islands) to ~19.5–18.5 ka. This infers ice retreated rapidly from the mid‐shelf after 21 ka, but the combined effects of bathymetric shallowing and pinning acted to stabilize the ice at the Aran Islands. However, marginal stability was short‐lived, with multiple coastal sites along the Connemara/Galway coasts demonstrating ice recession under terrestrial conditions by 18.2–17. ka. This pattern of retreat continued as ice retreated eastward through inner Galway Bay by 16.5 ka. South of Galway, the Kilkee–Kilrush Moraine Complex and Scattery Island moraines point to late stage re‐advances of the ice sheet into southern County Clare ~14.1–13.3 ka, but the large errors associated with the OSL ages make correlation with other regional re‐advances difficult. It seems more likely that these moraines are the product of regional ice lobes adjusting to internal ice‐sheet dynamics during deglaciation in the time window 17–16 ka. Publisher PDF

The study analyses a 7.5-m-thick sedimentary succession deposited in the largest sandur (the Gwda sandur, a glacial outwash plain) in NW Poland, during the late Weichselian (MIS 2). Although the study site is located in the distal zone of the sandur, its sedimentological features and palaeohydrological parameters reflect the presence of an energetic, powerful environment typical of the proximal zone. Three sedimentary units were recognized in the studied sedimentary succession: (1) lower unit — fine-grained sands with ripple cross-lamination and horizontal lamination; (2) middle unit — gravelly coarse-grained sands and sandy gravels with planar cross-stratification; and, (3) upper unit — sands and gravelly sands with trough cross-stratification. Although the age of deposition of the sandur is accepted to be convergent with that of end-moraines of the same phase, the sediments in the distal zone of the Gwda sandur correlate with an earlier glaciation phase/subphase. Our findings hint at a complex problem: large sandurs such as the Gwda sandur were probably deposited over a long time, and their successions might record the textural and structural features of the proximal subenvironment, even in their distal parts due to deglaciation-related shifting of the proximal zone of a sandur. This paper presents a new approach to analysing the depositional processes in large sandurs, shows a new light on glaciofluvial water supply dynamics of distal parts of sandurs, and may solve several fundamental problems related to the sandur deposition.

AMU Morasko soft clay is the normally consolidated, postglacial clayey silty sand to sandy clay, deposited during the last glaciation (Weichselian) within the marginal zone of end moraine of Posnanian Phase. These soils are characterized by low plasticity, high porosity and are fully saturated, therefore, from a geotechnical point of view they can be defined as soft clays. The over 10 meter thick complex of clayey glacial sediments is covered with fine and medium sands with single grains of gravel of the so-called first sandur level from the youngest glaciation. This kind of sediments are very common in the area of north-western Poland and, due to high compressibility, become a problematic subsoil for the shallow foundations. The high porosity and saturation also causes significant problems in obtaining high quality samples for laboratory tests. This means that in situ tests are very often the only possible and economically justifiable test methods. Extended investigations carried out on these clays, which provide reliable correlations between in situ and laboratory test results, will be very useful. For the purpose of this research paper, a wide variety of in situ (CPTU, DMT, FVT) and laboratory (physical properties, direct shear, oedometer) tests have been carried out on the material found at the depth of up to 16 m, in the area of 8 ha, within the campus of Adam Mickiewicz University (AMU) in Poznan, Poland. Preliminary investigations (performed four years ago) showed high uniformity of the test site. The current laboratory tests were carried out on both high quality natural samples and reconstructed samples. The rate effect on the results of some of the tests was also investigated. The obtained results allowed to present a wide geological and engineering characterization of these interesting glacial deposits.

This paper presents macro and microsedimentological data recording subglacial deformation of a sediment succession at Przeszkoda in north-central Poland under the Vistula Ice Stream at the southern fringe of the Scandinavian Ice Sheet during the Weichselian glaciation. The sediment succession consists of (i) undeformed outwash sand, (ii) deformed outwash sand, (iii) bedded till, and (iv) massive till. These deposits were examined in a closely sampled vertical profile for kinematic structures, macrofabrics, grain shape characteristics, and micromorphology (detrital components, microstructures, clast microfabrics). The analyzed parameters suggest that the deposits were generated by a progressive homogenization and mixing of local material with far-travelled detritus successively released from the active ice sole. Grain crushing and abrasion characteristics lack any obvious trends in the vertical profile, indicating that the deformation was focused in a thin (cm-scale) layer which progressively migrated upwards parallel with sediment accretion. The closely spaced thin sections were collected in the deformed outwash sand, bedded till and massive till units. These revealed formation and evolution of stress-induced foliation in the glacier bed whereby three microfabric generations including S1 (earliest), S2 and S3 (latest) foliation were recognized. The geometry of these microfabrics is consistent with their formation in response to the development of subhorizontal Y-type shears, and up-ice dipping P-type and down-ice dipping R-type Riedel shears within the subglacial shear zone. The geometry and cross-cutting relationships between the microfabrics throughout the succession reflects changing deformation styles within a thin deforming bed that migrated time-transgressively up the profile during till accretion. Strain magnitude accumulated in the whole sediment succession was low, in the range of 101 to 102, suggesting that enhanced basal sliding was an important component contributing to fast flow of the ice stream.

This study analyses the temperature distribution underneath the Piedmont Po Plain (NW Italy), where an important shallow aquifer exists due to fluvial and outwash deposits. A total of 118 thermal logs, for a total of 513 temperature measurements in spring 2008 and 585 in autumn 2008, were used to propose the conceptual thermal model of the vertical temperature distribution in the shallow aquifer of the western Po Plain. A constant temperature depth between 30 and 50 m below ground level was observed, under which aquifer temperatures were constant in the range 13−15 °C during the year independent of the external climatic condition. Above the constant temperature depth, the variable temperature zone, where the temperature is strongly influenced by external seasonal variations, was observed. Moreover, the collected thermometric data were processed, and the solution to the heat diffusion equation underground allowed us to determine the average distribution of temperature at different depths over time. This study provides a more detailed conceptual model of the temperature distribution in the Piedmont Po Plain. The model can be applied to other areas with similar hydrogeological characteristics (e.g., the eastern Po Plain or large plain alluvial aquifers). The paper also furnishes a description of the physical processes of heat diffusion in the shallow aquifer, as supported by statistical analysis. The proposed methodology may be adopted as a simple statistical method for the assessment of temperature values for the low-enthalpy geothermal exploitation of groundwater resources.

This paper presents a glacial geomorphological map of landforms produced by the Lago General Carrera–Buenos Aires and Lago Cochrane–Pueyrredón ice lobes of the former Patagonian Ice Sheet. Over 35,000 landforms were digitized into a Geographical Information System from high-resolution (

Aerosols and clouds play important roles in the Arctic climate. Conversely, aerosol emissions and cloud formation are affected by changes in the Arctic climate. This paper reviews studies of aerosols and clouds performed during the Arctic Challenge for Sustainability (ArCS) project carried out by the National Institute of Polar Research (NIPR) in Japan and collaborating institutions. The ArCS project included intensive studies of black carbon aerosols (BC). We installed Continuous Soot Monitoring System (COSMOS) instruments to measure atmospheric BC at four locations in the Arctic, establishing the Arctic BC COSMOS Measurement Network (ABCM-net). We also measured BC concentrations in snowpack in extensive areas of the Arctic and showed that previous studies have greatly overestimated BC in snowpack. We developed and improved new aerosol models that achieved better agreements with measurements of BC in the Arctic atmosphere, snowpack, and falling snow. We made new estimates of radiative forcing of BC in the Arctic atmosphere and snow/ice surfaces that lower their albedo. In addition to these researches on BC, we made accurate measurements of ice nucleating particles (INPs) at Ny-Alesund, Svalbard, showing that their concentrations increased in summer as a result of dust particle emissions from glacial outwash sediments. This high ice nucleating ability was likely due to the presence of organic substances mixed with the dust particles. We also made continuous cloud radar measurements and the first continuous in-situ measurements of cloud microphysical properties in the Arctic at Ny-Alesund. Results from these cloud measurements and their relationship with aerosols are described.

The Rospuda subglacial channel hosts not only deep ribbon lakes and the Rospuda River itself, but also an outwash plain. The paper deals with a lithofacies analysis of deposits from exposures within the Rospuda outwash plain. With the support of geomorphological and geological analyses, it has been found that the outwash plain formed along the Rospuda subglacial channel that was being exposed from under the ice cover. The lithological record of the Rospuda outwash plain shows a distinct division into a proximal and a distal zone. The deposits under study reveal a record of a break in basial sedimentation, when ice-wedge casts developed under conditions of periglacial climate. The development of the Rospuda outwash plain is linked with the ice-marginal zone of the Pomeranian phase, similarly to the Olecko-Rajgród outwash plain that is located to the west.

The aim of this paper is to quantify and map the impact of the post‐Little Ice Age climate change on the coastal evolution on three glacier catchments in the Kongsfjorden area in Svalbard. Climatic data at Ny‐Alesund indicate an increase in the annual mean air temperature of +4 °C from 1969 to 2016 and an increase in precipitation. On the northern coast of the Brogger Peninsula, the Austre Lovenbreen, Midtre Lovenbreen, and Vestre Lovenbreen glaciers have experienced a net retreat in response to changing meteorological conditions. Because of this retreat, the glaciers have disclosed a large area of 7 km2 composed of terrigenous sediments. These sediments are transported by runoff and created coastal sandur deltas. Channel network behavior has been studied using the computation of the active floodplain width by photointerpretation, which decreased in average from 1966 to 2010. This demonstrated a contraction of the active braided belt and a decrease in the number of braided channels. A photointerpretation analysis combined with acquisition of dGPS data during field work shows a mean shoreline progradation of +0.16 m a−1 from 1966 to 2016, with a maximal advance of +82 m seaward. Since 1966, coastal progradation has decreased in time with higher mean values at the beginning of the studied period and an erosional trend from 1990. The sublittoral area was studied using analog side scan sonar in 2009, 2011, 2012, and 2017. Three prodeltas were identified and underwent a huge extension from 2009 to 2017. In the light of this knowledge, our main conclusion is that, by retreating, glaciers have an impact on the sediment availability and on the capacity of the fluvial system to effectively transport sediment to the shoreline. These two factors control the overall coastal evolution by regulating the sediment supply to the coastal area. The coastal zones that were fed with sediments by runoff have experienced a coastal progradation, and those that lost this supply have undergone a coastal recession. Due to the contraction of proglacial floodplains, current progradation concerns restricted coastal areas.

Estimation of groundwater recharge is one of the most challenging subjects in hydrogeology. It is a critical factor influencing the pollution migration, assessment of aquifer vulnerability to contamination, small-scale groundwater budget calculation, modeling of nutrient cycling and detailed flow path calculations. In Poland an infiltration rate method is widely used, which depends on a system of rate coefficients referring to the type of soil in the vadose zone and shows which part of the precipitation actually reaches the water table. The paper presents results of numerical simulations of vertical flow in unsaturated zone of an experimental site located on Brda outwash plain. Two simulations for varying vegetative cover (pine forest and grass) were performed. The results were compared with five infiltration rates classifications.

Understanding the style and pattern of retreat of the offshore sectors of the last British-Irish Ice Sheet (BIIS) is critical to any attempt to reconstruct its history following the Last Glacial Maximum (LGM). This paper presents a new seismo-stratigraphic analysis of Quaternary deposits on the inner continental shelf offshore of southwestern Scotland. It correlates these data with new high resolution seafloor bathymetry and sediment cores to reconstruct the post-LGM retreat dynamics of the Hebrides Ice Stream, a major outlet of the last BIIS which drained across the continental shelf offshore of northwest Britain. Two primary glacigenic units (Units III and IV) are observed in seismic sequences from the region. Unit III partly corresponds to the previously defined Barra Formation, but is re-interpreted here as a time-transgressive subglacial to ice-proximal deposit. On the mid-shelf, this unit comprises grounding-zone wedges (GZWs). Within inshore waters and sea lochs Unit III can be found at or near seabed, where it is associated with retreat moraines, as well as with proglacial outwash sediments near the Kintyre coast (RSL ~10 m OD). The younger Unit IV (equivalent to the Jura Formation) represents ice-proximal to hemipelagic conditions. Bathymetric data imaged streamlined subglacial landforms recording ice sheet flow onto the inner shelf and a variety of transverse landforms collectively interpreted as moraines recording episodic retreat. These new data indicate that during the last deglaciation of the shelf offshore of southwestern Scotland the retreat dynamics of the Hebrides Ice Stream followed three main stages: i) tidewater margin retreat punctuated by stillstands on the inner shelf, ii) topography-controlled fjordic retreat, with evolution from a coherent ice-sheet to separate tidewater glaciers, and iii) stabilisation at the transition from a tidewater to land-based ice margin.

Deglacial sequences typically include backstepping grounding zone wedges and prevailing glaciomarine depositional facies. However, in coastal domains, deglacial sequences are dominated by depositional systems ranging from turbiditic to fluvial facies. Such deglacial sequences are strongly impacted by glacio-isostatic rebound, the rate and amplitude of which commonly outpaces those of post-glacial eustatic sea-level rise. This results in a sustained relative sea-level fall covering the entire depositional time interval. This paper examines a Late Quaternary, forced regressive, deglacial sequence located on the North Shore of the St. Lawrence Estuary (Portneuf Peninsula, Québec, Canada) and aims to decipher the main controls that governed its stratigraphic architecture. The forced regressive deglacial sequence forms a thick (>100 m) and extensive (>100 km2) multiphased deltaic complex emplaced after the retreat of the Laurentide Ice Sheet margin from the study area ca 12 500 years ago. The sedimentary succession is composed of ice-contact, glaciomarine, turbiditic, deltaic, fluvial and coastal depositional units. A four-stage development is recognized: (i) an early ice-contact stage (esker, glaciomarine mud and outwash fan); (ii) an in-valley progradational stage (fjord head or moraine-dammed lacustrine deltas) fed by glacigenics; (iii) an open-coast deltaic progradation, when proglacial depositional systems expanded beyond the valley outlets and merged together; and (iv) a final stage of river entrenchment and shallow marine reworking that affected the previously emplaced deltaic complex. Most of the sedimentary volume (10 to 15 km3) was emplaced during the three-first stages over a ca 2 kyr interval. In spite of sustained high rates of relative sea-level fall (50 to 30 mm·year-1), delta plain accretion occurred up to the end of the proglacial open-coast progradational stage. River entrenchment only occurred later, after a significant decrease in the relative sea-level fall rates (-1), and was concurrent with the formation and preservation of extensive coastal deposits (raised beaches, spit platform and barrier sands). The turnaround from delta plain accretion to river entrenchment and coastal erosion is interpreted to be a consequence of the retreat of the ice margin from the river drainage basins that led to the drastic drop of sediment supply and the abrupt decrease in progradation rates. The main internal stratigraphic discontinuity within the forced regressive deglacial sequence does not reflect changes in relative sea-level variations.

After retreat from the Angermünde Ice Margin, the Weichselian inland ice sheet fell apart into different independently acting ice tongues in the eastern Uckermark. In this region (bordering Poland), between the Angermünde and Penkun Ice Margins only the Schönermark Intermediate Ice Margin has been described before. This paper postulates two more ice margins: a Welse North Ice Margin and a Welse South Ice Margin. The Welse South Ice Margin is a ridge in the area northwest and south of the Welse stream (lower course) and can be followed over the villages Zehnebeck - Wendemark - Passow - Herrenhof - Berkholz. The Welse South Ice Margin is seen as a possible simultaneous continuation of the Zichow-Golm Ice Margin. Subglacial valleys developed, but unique drainage paths and sander at the Zichow-Golm Ice Margin and at the Welse South Ice Margin could not be found. In the area of Wartin - Schönow - Kunow - Hohenfelde a distinct ridge can also be seen, here named Welse North Ice Margin. It is conceived as a possible simultaneous continuation of the Gerswalde Ice Margin. An exposure in the gravel pit south of Kunow shows exemplary the different push phases of the inland ice and periglacial phenomena in this area. The main meltwater direction was from north to south and between Wartin and Blumberg a sander terrace was formed at a level of 50 - 60 m above NHN in the Randow Valley. Nach Auflösung der Angermünder Eisrandlage kam es im Weichselspätglazial zu verschiedenen unabhängig voneinander wirken- den Gletscherzungen in der östlichen Uckermark. Zwischen der Angermünder Staffel und der Penkuner Staffel ist bisher nur der Schönermarker Zwischenstaffel beschrieben worden. In dieser Arbeit werden zwei weitere Eisrandlagen postuliert: eine Welsesüdrandlage und eine Welsenordrandlage. Die Welsesüdrandlage ist ein Höhenzug im Raum nordwestlich und südlich des Welse-Flusses und ist über die Orte Zehnebeck - Wendemark - Passow - Herrenhof - Berkholz zu verfolgen. Sie wird als eine Art (und möglich zeitgleiche) Fortsetzung der Zichow-Golmer Zwischenstaffel aufgefasst. Eindeutige Entwässerungsbahnen der Zichow-Golmer Zwischenstaffel und der Welsesüdrandlage konnten nicht gefunden werden. Im Raum Wartin - Schönow - Kunow – Hohenfelde ist ebenfalls ein Höhenzug zu erkennen; die hier Welsenordrandlage genannt wird. Sie wird als eine Art (möglich zeitgleiche) Fortsetzung der Gerswalder Staffel aufgefasst. Ein Aufschluss in der Kiesgrube südlich von Kunow zeigt beispielhaft die verschiedenen Stauchungsphasen und Periglazialerscheinungen in diesem Bereich. Die wichtigste Schmelzwasserrichtung war von Nord nach Süd und zwischen Wartin und Blumberg wurde dabei in Höhe von 50–60 m NHN im Randowtal eine Sanderterrasse gebildet.

During the Pleistocene the Scandinavian ice sheet drained huge quantities of sediment-laden meltwaters. These meltwaters supplied ice-marginal valleys that formed parallel to the front of the ice sheet. Not without significance was the supply of ice-marginal valleys from extraglacial rivers in the south. Moreover, periglacial conditions during and after sedimentation in ice-marginal valleys, the morphology of valley bedrocks, and erosion of older sediments played important roles in the depositional scenarios, and in the mineralogical composition of the sediments. The mechanisms that controlled the supply and deposition in ice-marginal valleys were analysed on the basis of a Pleistocene ice-marginal valley that was supplied by northern and southern source areas in the immediate vicinity. Investigations were conducted in one of the largest ice-marginal valleys of the Polish-German lowlands, i.e., the Toruń-Eberswalde ice-marginal valley, in sandurs (Drawa and Gwda) supplied sediments and waters from the north into this valley, and on extraglacial river terraces (pre-Noteć and pre-Warta rivers), formed simultaneously with the sandurs and ice-marginal valley (Pomeranian phase of Weichselian glaciation) supplied sediments and waters from the south into this valley. A much debated question is how similar, or different, depositional processes and sediments were that contributed to the formation of the Toruń-Eberswalde ice-marginal valley, and whether or not it is possible to differentiate mostly rapidly aggraded sandur sediments from ice-marginal valley sediments. Another question addresses the contribution of extraglacial feeding of the Toruń-Eberswalde ice-marginal valley. These matters were addressed by a wide range of analyses: sediment texture and structure, architectural elements of sediments, frequency of sedimentary successions, heavy-mineral analysis (both transparent and opaque heavy minerals), analysis of rounding and frosting of quartz grains, and palaeohydrological calculations. Additionally, a statistical analysis was used. The specific depositional conditions of distribution of sediments in ice-marginal valley allow to distinguish new environment of ice-marginal valley braided river. The spectrum of depositional conditions in the Toruń-Eberswalde ice-marginal valley and their specific palaeohydraulic parameters allow to distinguish three coexisting zones in the ice-marginal valley braided-river system: (1) deep gravel-bed braided channel zone with extensive scours, (2) deep sand-bed braided channel zone with transverse bars, and (3) marginal sand-bed and gravel-bed braided channel zone with diamicton and breccia deposition, which were characterised in detail. Some of the results have been published previously, which is why they are discussed in the present paper within the context of new data

International audience; Fired glaciofluvial beds in outwash considered to date from the onset of the Younger Dryas Event (~ 12.9 ka) in the northwestern Venezuelan Andes are considered equivalent to the Black Mat deposits described in other areas of North and South America and Europe. It may be equivalent to sediment recovered from other sites containing beds with spikes of cosmic nuclides and charcoal indicating the presence of widespread fire, one of the signatures of the Black Mat conflagration that followed the proposed breakup of Comet Encke or an unknown asteroid over the Laurentide Icesheet at 12.9 ka. In the northern Andes at Site MUM7B, sediment considered coeval with the Black Mat contains glassy carbon spherules, tri-coatings of C welded onto quartz and feldspar covered with Fe and Mn. Monazite with excessive concentrations of REEs, platinum metals including Ru and Rh, possible pdf's, and disrupted/brecciated and microfractured quartz and feldspar from impacting ejecta and excessive heating summarize the data obtained so far. The purpose of this paper is to document the physical character, mineralogy and biotic composition of the Black Mat.