Search

In this study, a glacial lake-outburst flood was documented in the immediate foreland of the maximum phase of the Wartanian (Warthian, Late Saalian, MIS 6) Glaciation at Adamow in south central Poland. The structural and textural analyses of the sediments, as well as palaeohydraulic analysis, were carried out in the proximal part of the outwash plain where a fragment of the floodwater drainage system comprising buried erosional channels have been documented. Their fill reached a thickness of up to 11 m and was composed of poorly sorted, massive gravels with boulders, as well as horizontally, sub-horizontally, low-angle, and cross-stratified gravels. The coarse sediments were found to be inversely and normally graded. These sediments constituted the records of two subsequent flooding episodes. In the channel fill, the lenticular accumulations of gravel were identified and interpreted as buried large gravel dunes, while exhibiting a thickness of up to 2.5 m. Traces of sediment diapirism at the contact of channel fill and underlying sediments were also documented. Deformation was observed to originate from liquefaction caused by the rapid depositional loading of flood deposits. The example used in this study exhibited that the impact of glacial lake-outburst floods in shaping the marginal zones and foreland of ice sheets in the North European Plain was higher than that considered earlier. This example also showed a different case of glacial outburst flood in the foreland of the Middle Pleistocene ice sheets of Europe than that already known, which includes the discharge of sub- or englacial meltwater reservoirs emanated from a large proglacial ice-dammed lake.

Glacial landforms are a significant element of landscape in many regions of Earth. The increasing availability of high-resolution digital elevation models (DEMs) provides an opportunity to develop automated methods of glacial landscape exploration and classification. In this study, we aimed to: 1) identify glacial landforms based on high-resolution DEM datasets; 2) determine relevant geomorphometric and spectral parameters and object-based features for the mapping of glacial landforms; and 3) develop an accurate workflow for glacial landform classification based on DEM. The developed methodology included the extraction of secondary features from DEM, feature selection with the Boruta algorithm, object-based image analysis, and random forest supervised classification. We applied the workflow for three study sites: one in Svalbard and two in Poland. It allowed the identification of six categories of glacial landforms: till plains, end moraines, hummocky moraines, outwash/glaciolacustrine plains, valleys, and kettle holes. The majority of relevant secondary features represented DEM spectral parameters calculated from 2-D Fourier analysis. The supervised classification models with the highest performance exhibited up to 96% overall accuracy with regard to a groundtruth dataset. This study showed that glacial landforms can be identified using novel image-processing methodology and spectral parameters of high-resolution DEM. The complete classification workflow developed herein provides a solution for the transparent generation of thematic maps of glacial landforms that may be reproducible and transferrable to various glacial regions worldwide.

The spatial and temporal controls on variability of the relative contributions of groundwater within and between flow systems to shallow lakes in the low-relief glaciated Boreal Plains of Canada were evaluated. Eleven lakes located in a coarse glacial outwash, of varying topographic positions and potential groundwater contributing areas, were sampled annually for stable O and H isotope ratios over the course of 8 years. It was demonstrated that landscape position is the dominant control over relative groundwater contributions to these lakes and the spatial pattern of the long-term isotopic compositions attributed to groundwater overrides interannual variability due to evaporative effects. Lakes at low landscape positions with large potential groundwater capture areas have relatively higher and more consistent groundwater contributions and low interannual variability of isotopic composition. Isolated lakes high in the landscape experience high interannual variability as they have little to no groundwater input to buffer the volumetric or isotopic changes caused by evaporation and precipitation. An alternative explanation that lake morphometry (area and volume) control long-term isotopic compositions is tested and subsequently refuted. Landscape position within coarse outwash is a strong predictor for relative groundwater input; however, surface-water connections can short circuit groundwater pathways and confound the signal. A hydrogeological case study for three of the study lakes is used to contextualize and further demonstrate these results.

The Alps were covered by a complex ice sheet comprising various centres of glaciation with occasionally dome-like structures from which huge valley glaciers flowed out. Systems of transection (interconnected valley glaciers) as well characterised the Alps. The equilibrium line altitude (ELA) across the Alps was between 1000 and 1700 m, with a general trend of rising from the margins to the centre. At sites farther to the east and south, smaller glaciers were present. Glaciers extended onto the northern and southern forelands and formed huge piedmont lobes. Frontal moraines filled the amphitheatres broadly defined by moraines built-up during earlier glaciations. Fields of drumlins were shaped in the footprints of the large piedmont glaciers on the northern flank of the Alps from the Rhone Glacier in the west to the Salzach Glacier in the east. The glaciers delivered remarkable volumes of outwash. On the south side of the Alps, huge fans were constructed. In the north, outwash gravels were largely confined to the established river valleys. The timing of the Last Glacial Maximum Alpine glacier fluctuations has been studied with radiocarbon dating, luminescence techniques, and cosmogenic nuclide surface exposure dating. Expansion of glaciers can be shown to have begun as early as 32.5–30.5 ka cal BP, with glaciers reaching the forelands already by 29 ka cal BP. Most systems exhibit two main advance phases, which in the south have been dated to 26–25 and 23–22 ka cal BP.

International audience; Middle Pleistocene glaciation in the Pyrenees is still poorly documented, but the record of ice fluctuations that occurred before 29 ka within the time span of the Late Pleistocene has benefited from a growing catalogue of geochronological data. Here we provide an exhaustive review of results obtained from different generations of ice-marginal deposits for that period, including 14C ages from glaciolacustrine deposits, 10Be and 36Cl exposure ages from boulders embedded in moraines and/or glacially scoured bedrock steps, and optically stimulated luminescence ages from glaciofluvial outwash terraces. Data currently available indicate that the most extensive Pyrenean glaciation of the Late Pleistocene occurred prior to the Last Glacial Maximum (LGM), but that this outermost stadial position (local LGM) was reached on not just one, but several occasions between MIS (marine isotopic stage) 5b (or MIS 4) and MIS 3. Some preliminary results also document major glacier fluctuations during MIS 3.

Sandy outwash and glacial till soils compose large amounts of public forestland due to historically poor agricultural yields. The outwash soils have low fertility, poor nutrient retention and are restricted from whole-tree harvesting (WTH) in some states, whereas the glacial till has medium nutrient retention and fertility, and is unrestricted from WTH. To assess the long-term sustainability of harvesting, a nutrient budget was constructed from field measurements, the National Cooperative Soil Survey (NCSS) database, and literature values for stem-only harvesting (SOH) and WTH at a 45-year rotation length and 11 rotations were simulated. The budgets showed that SOH and WTH recovery years, or the time necessary for the inputs to match outputs through leaching and one harvest, exceeded common rotation lengths for both soil types under all weathering scenarios, and the average WTH reduced the total available rotations by one harvest. The large variation in soil nutrient pools and harvest removals complicated the ability to identify the difference between SOH and WTH early in the model, but differences became apparent with sequential harvests. The recovery years were 2–20 times the 45-year rotation length under all weathering rates. Taken together, models in this study bridge the gap between short- and long-term studies and bring into question the sustainability of WTH and SOH practices on nutrient-poor soils.

Reconstructing the growth and decay of palaeo-ice sheets is critical to understanding the relationships between global climate and sea-level change and to testing numerical ice sheet models. In this study, we integrate recently acquired high-resolution 2D seismic reflection and borehole datasets from two wind-farm sites offshore of the Netherlands to investigate the sedimentary, geomorphological, and glaciotectonic records left by the Saalian Drenthe substage glaciation, when Scandinavian land ice reached its southernmost extent in the southern North Sea (ca. 160 ka, Marine Isotope Stage 6). A complex assemblage of glaciogenic sediments and glaciotectonic structures is buried in the shallow subsurface. The northern wind-farm site revealed a set of NE–SW-oriented subglacial meltwater channels filled with till and glaciofluvial sediments and an E–W-trending composite ridge with local evidence of intense glaciotectonic deformation that denotes the maximum limit reached by the ice. Based on the identified glacial geomorphology, we refine the mapping of the maximum ice sheet extent offshore, revealing that the ice margin morphology is more complex than previously envisaged and displaying a lobate shape. Ice retreat left an unusual paraglacial landscape characterised by the progressive infilling of topographic depressions carved by ice-driven erosion and a diffuse drainage network of outwash channels. The net direction of outwash was to the west and southwest into a nearby glacial basin. We demonstrate the utility of offshore wind-farm data as records of process–form relationships preserved in buried landscapes, which can be utilised in refining palaeo-ice sheet margins and informing longer-term drivers of change in low-relief settings.

An acoustic survey using sub-bottom sonar (SBS) and Autonomous Underwater Vehicle EcoMapper (AUVEM) combined with coring was used for the investigation of bottom topography, thickness of the sediments, and geodynamic factors influencing the postglacial deposition in Tatra Mts. lakes. This combined study of seven lakes shows four basic acoustic units and four subunits that are interpreted in terms of stratigraphy and lithology. However, the presence of particular acoustic units may not be encountered in all the lakes due to the effects of local and internal lake processes. Thick horizontal reflections with high amplitude reflectors characterize the bedrock or the infill with a thickness of more than 6 m. Chaotic internal reflection configuration and high amplitude reflectors are common and reflect the glacigene deposits of unknown thickness in the bottom of the lakes. Above the signals of glacigene sediments lie reflections with weak to moderate amplitude reflectors, and with a parallel and chaotic configuration. They correspond to the glaciolacustrine laminated clay and silt and postglacial gyttja that contain clastic outwash from various mass movement deposits. The transition zone between these two SBS reflections is formed by a discontinuous, parallel and wavy configuration with the acoustic bottom. This type of signal is interpreted as a mixture of cobbles, boulders, and fine-grained sediments. The exact lithological content and the presence of the acoustic units are determined by other factors that may not be visible around the lakes and can cause stratigraphic hiatuses. As a prominent and un-recognized factor in the Tatra Mts. until now is the presence of the bottom springs (pockmarks) of the non-karstic origin, which effectively disturb the fine clastic and organic matter deposition and hence can limit the use of the lake deposit for palaeoclimatic and palaeoecological studies. The mass movement processes – debris flow, rockfall – forming the mountain geo-relief are frequent and their products are visible in the marginal facies. The sonar inspection also provides evidence of mass movement deposits, which have no indication on the terrestrial environment and thereby represent intralacustrine landslides as a result of bedrock instability due to the late Pleistocene deglaciation or Holocene climatic variability.

Seabird’s role in the soil landscape evolution can be dramatic, specifically where they establish colonies. Loose colonies allow for point-centered input from avifauna at Breiðamerkurjokull glacier outwash plane in SE-Iceland. The birds utilize the open area within the deglaciated fore-land for roosting, perching, and nesting, which has resulted in striking differences in the soil environment. Using a chronosequence based on when moraines were exposed on the foreland, the aim of this study was to 1) assess changes in soil chemical properties and nutrient availability, 2) compare the differences between sites where bird activity (roosting, perching, or nesting) has led to the formation of grassy hummocks, and the surrounding moraines, and 3) investigate evidence of development of selected andic properties over time. The results strongly indicate that both the moraine and hummock soils are developing from Vitrisols towards Andisols. This is supported by the distinct trend that less phosphorus (P) is available in the soil with time, consistent with andic soil properties. Maximum P-retention was reached in the 127-year old moraine soil and hummock at 26.6%, 48.9% P respectively, and 87.5% P in a nearby woodland reference site. Cation exchange capacity (CEC) in both soil environments showed increased concentration of cations with time, presenting greater values in the hummock soils. Other soil properties, including available ammonium, nitrate, nitrite, pH H2O, and pH NaF, demonstrated the stark effects of avifauna on the soil chemical properties. Organic inputs from birds added to the bio-nutrients and organic matter (OM) in the soil, which enriches vegetation. The data from this study show that avifauna can locally enhance soil formation creating a positive feedback mechanism between soils and vegetation. The results from this study show that avifauna can locally enhance the chemical properties, plant nutrient availability, and soil formation.

Large glaciers and ice caps formed in the Mediterranean mountains during the cold stages of the Pleistocene and some small glaciers remain today. Here we review 157 outputs that include radiometric dates on glacial deposits or outwash in the Mediterranean published between 1975 and 2020. The last decade has seen a striking increase in the use of terrestrial cosmogenic nuclide (TCN) dating and this has revolutionised our understanding of the Late Pleistocene glacial record. Our meta-analysis of 1663 radiometric ages highlights much greater complexity in the timing of Pleistocene glaciation across the region than hitherto recognised. Evidence from multiple dating methods, in a range of depositional settings, confirms that the Mediterranean glacial record extends through all of the Late Pleistocene and deep into the Middle Pleistocene. Evidence of Early Pleistocene glacial activity has been recognised from outwash deposits in the Julian Alps of Slovenia. The most extensive glaciations occurred during the Middle Pleistocene: their ages have been established primarily by using 40Ar/39Ar in the Italian Apennines and U-series dating in the glaciokarst of the Balkans. The Late Pleistocene glacial geochronologies are based on optically stimulated luminescence (OSL), radiocarbon and TCN dating. TCN dating is now the dominant method for dating Late Pleistocene glacial landforms. It is now clear that glaciers were present throughout the Late Pleistocene and, in most parts of the Mediterranean, they were at or near their maximum extent before the global last glacier maximum (27.5–23.3 ka). The outwash record in river valleys downstream of the glaciated terrains confirms that glaciers were important agents of landscape change throughout this period. Deglaciation in the Mediterranean mountains was punctuated by glacier stabilisations as well as some readvances towards the very end of the Pleistocene. The deglacial trend has continued throughout the Holocene with rapid change in recent decades due to rising global temperatures. Some small glaciers remain today due to the influence of locally favourable topoclimatic factors. For much of the Quaternary Period conditions in the Mediterranean mountains involved much more extensive glaciation than recorded at any time in the Holocene.

Loess deposits along the northern fringe of the European loess belt potentially record past changes in dust emission from areas proximal to former ice sheets. Recent chronologies from loess deposits across this region generally agree on greatly enhanced dust deposition rates when the Fennoscandian Ice Sheet reached its maximum extent during the late last glacial. However, uncertainties over the material's source and origin limit understanding of the causes of this enhanced dust activity. In particular, loess in southwestern Poland has been attributed to multiple origins, mainly involving glaciofluvial outwash plains along the Fennoscandian Ice Sheet margin and/or local sources in the mountainous areas of the Sudetes and Western Carpathians. Here we apply detrital zircon U–Pb age analyses for a large number of grains recovered from four loess samples taken from different stratigraphic units exposed at Bialy Kościol in southwestern Poland, previously luminescence dated to MIS 4–2, to assess loess provenance as well as its temporal evolution during last glacial Fennoscandian Ice Sheet fluctuations. Furthermore, we analysed the detrital zircon U–Pb age spectra of five samples from potential source sediments to constrain the history of sediment recycling and mixing within the Northern European Plain prior to deflation and loess deposition. The broad range of zircon age components detected in the four loess samples suggests both Fennoscandian and closer Peri-Gondwanan proto-sources while a narrow, dominant Carboniferous age peak is consistent with sourcing from the local Strzelin Hills in the Sudetic foreland. However, the presence of both Fennoscandian and Peri-Gondwanan derived grains in samples from potential source sediments reveals that this mixture of sediment sources is widespread across the Northern European Plain, as a result of long-term glacial and fluvial reworking of cover sediments in the proglacial area throughout the Quaternary. Local rivers draining the Sudetic foreland transported this Fennoscandian-Peri-Gondwanan sediment mixture along with particles denuded from the Strzelin Hills, resulting in a nearby, temporally stable dust source for the Bialy Kościol loess during MIS 4–2, while dust emission rates were substantially increased during the last glacial maximum. Given that our model for loess formation at Bialy Kościol essentially involves sediment distribution via rivers prior to short distance aeolian transport, we infer that the proportion of northern ice sheet derived particles in European loess deposits is mainly controlled by the drainage pattern of major rivers in relation to Pleistocene ice margins where glaciofluvial sediment is abundant. Based on the presence of Fennoscandian derived zircon grains in European loess deposits, we constrain a southern limit of the influence of northern ice sheet dust sources along the central European highlands that currently divide drainage between the Northern European Plain and the Danube Basins.

Atmospheric carbon dioxide reached a record concentration of 419 parts per million in May 2021, 50% higher than preindustrial levels at 280 parts per million. The rise of CO2 as a heat-trapping gas is the principal barometer tracking global warming attributed to a global average increase of 1.2 °C over the last 250 years. Ongoing global warming is expected to perturb extreme weather events such as tropical cyclones (hurricanes/typhoons), strengthened by elevated sea-surface temperatures. The melting of polar ice caps in Antarctica and Greenland also is expected to result in rising sea levels through the rest of this century. Various proxies for the estimate of long-term change in sea-surface temperatures (SSTs) are available through geological oceanography, which relies on the recovery of deep-sea cores for the study of sediments enriched in temperature-sensitive planktonic foraminifera and other algal residues. The Pliocene Warm Period occurred between ~4.5 and 3.0 million years ago, when sea level and average global temperatures were higher than today, and it is widely regarded as a predictive analog to the future impact of climate change. This work reviews some of the extensive literature on the geological oceanography of the Pliocene Warm Period together with a summary of land-based studies in paleotempestology focused on coastal boulder deposits (CBDs) and coastal outwash deposits (CODs) from the margin of the Pacific basin and parts of the North Atlantic basin. Ranging in age from the Pliocene through the Holocene, the values of such deposits serve as fixed geophysical markers, against which the micro-fossil record for the Pliocene Warm Period may be compared, as a registry of storm events from Pliocene and post-Pliocene times.