Terminal Moraines Research Articles

Marine record of late-glacial readvance and last recession of Laurentide ice, inner Frobisher Bay, Baffin Island, Arctic Canada

The Cockburn Substage readvance marks the last major late-glacial advance of the northeast sector of the Laurentide Ice Sheet on Baffin Island. The causes of this abrupt, late reversal of retreat are still unclear, but greater chronological control may provide some insight. To date, the literature has focused on the large terminal moraines in the region, providing a date of readvance (circa 9.5–8.5 ka cal BP). In Frobisher Bay, the Cockburn Substage readvance and recession onshore are marked by a series of moraines spread over ∼20 km along the inner bay. Acoustic marine mapping reveals five distinct transverse ridges, morphologically suggestive of grounding-zone wedges, and two later fields of DeGeer moraines on the floor of the inner bay. These indicate that the style of ice retreat (beginning no later than 8.5 ka cal BP) changed over time from punctuated recession of a floating ice front (20 km over >680 years, with four pauses) to more regular tidewater ice-front retreat, reaching the head of the bay 900 years or more after withdrawal from the outer Cockburn limit. The established chronology for final recession in the region is based largely on radiocarbon dating of bulk shell samples and single shells of deposit-feeding molluscs, notably Portlandia arctica, affected by old carbon from carbonate-rich sediments. Sedimentary analysis and judicious sampling for 14C dating of glaciomarine and marine facies in seabed sediment cores enables development of a late- and post-glacial lithostratigraphy that indicates final withdrawal of ice from the drainage basin by 7 ka cal BP.

Permafrost as the main factor controlling the fluvial sedimentation style on glaciomarginal fans

This study describes the sedimentary successions of two glaciomarginal fans (=end moraines) deposited during MIS 6 and MIS 2 in the eastern and north-western part of Poland. Sedimentological analyses of the successions indicate they were both deposited close to the ice sheet margin and are dominated by extensive gravelly and sandy sheet beds derived from the upper flow regime with single ice-wedge structures. Qualitative and quantitative analysis of the pancake-like gravelly and sandy sediments was performed using Markov chain analysis. The presence of these, admittedly common, sedimentary successions raises two key points: why sheetfloods are so common on glaciomarginal fans instead of in-channel flows, and whether sedimentary rhythms deposited by sheetfloods represent the full depositional records, or only partial ones due to accompanying erosion. While both points remain unclear, the answers to these questions may be connected to the presence of permafrost, which occupied the foreland of the ice sheet where the glaciomarginal fans were deposited: it can control the type of proglacial river flows on glaciomarginal fans, the depth of erosion and influence the record of sedimentary rhythms.

From deglaciation to postglacial filling: post-LGM evolution of an isolated glacier system at the northern fringe of the Eastern Alps (Austria)

ABSTRACT During the last glacial maximum (LGM), large parts of the European Alps were occupied by an extensive interconnected system of valley glaciers. At lower elevations on the eastern fringe of the Alps, only a patchy pattern of isolated glaciers developed. Erosion by many of these smaller glaciers was however sufficient to excavate subglacial basins (‘overdeepening’) large enough to act as sedimentary archives of deglaciation processes. To constrain the deglaciation history and the post-LGM evolution of an isolated glacial system, we analyzed the geomorphology and the sedimentary record of a local overdeepening at the northern fringe of the Northern Calcareous Alps. We focus on the heavily silted lake system Taferlklaussee (TKS) (Höllengebirge massif, Austria) confined by a succession of terminal moraines and a steep headwall. Field techniques (mapping, Direct Current Resistivity, and core drilling), lab techniques (lithostratigraphic analyses and radiocarbon dating) and Geographic Information System (GIS) analyses are employed to document dynamics of erosion and sedimentation after deglaciation. We discuss drivers and controls of paraglacial landscape evolution. The almost complete postglacial (lake) record indicates abundant sediment input during the lateglacial and early Holocene, but strongly reduced dynamics since the Mid-Holocene. Sediment storage volumes range between 3.83 Mm³ and 5.75 Mm³ and lithology-specific mechanical denudation rates range between 0.8 mm/a and 1.7 mm/a depending on the scenario used. The study provides a well-constrained reference for the depositional dynamics of isolated LGM glacier systems of the Eastern Alps. It highlights the potential of using related sedimentary records to constrain the local variability in postglacial landscape evolution.

Reconstruction of the Upper Slope Conditions of an Extraordinary Hydro-Meteorological Event Along the Jamapa Glacier Drainage System, Citlaltépetl (Pico de Orizaba) Volcano, Mexico

A singular precipitation event on the summit glacial slopes of Mexico’s highest volcanic peak, Citlatépetl (also known as Pico de Orizaba), associated with the passage of Hurricane Ernesto across the southern Mexico mainland in August 2012, resulted in a debris flow at altitudes above 4,400 m asl, culminating in a hyperconcentrated flow downstream that had major impacts to a river valley’s channel morphology as well as to communities along a 25 km runout. The lahar originated at the terminal moraine and proglacial ramp of the Little Ice Age (LIA) extent of Citlaltépetl’s Jamapa glacier. Precipitation amounts were estimated based on nearby CONAGUA stations, but also on TRMM satellite images leading to an estimated 106 mm for a 3 day total, with 85 mm (80% of the total) falling on August 9th, the date when the lahar event occurred. The initial debris flow removed a minimum estimated 60,000 m3 of material from the proglacial ramp. A possible causative scenario is that the precipitation event overpressured the groundwater hydrology of an already unstable glacial-melt-saturated moraine. We demonstrate a methodology for the recreation of a pre-event landscape and the environmental conditions at the onset of the lahar, utilizing satellite products, in-situ geomorphological and geological evidence, and UAS technology.

Postglacial slip distribution along the Teton normal fault (Wyoming, USA), derived from tectonically offset geomorphological features

Along the eastern front of the Teton Range, northeastern Basin and Range province (Wyoming, USA), well-preserved fault scarps that formed across moraines, river terraces, and other geomorphological features indicate that multiple earthquakes ruptured the range-bounding Teton normal fault after the Last Glacial Maximum (LGM). Here we use high-resolution digital eleva­tion models derived from lidar data to determine the vertical slip distribution along strike of the Teton fault from 54 topographic profiles across tectonically offset geomorphological features along the entire Teton Range front. We find that offset LGM moraines and glacially striated surfaces show higher vertical displacements than younger fluvial terraces, which formed at valley exits upstream of LGM terminal moraines. Our results reveal that the tectonic off­sets preserved in the fault scarps are post-LGM in age and that the postglacial slip distribution along strike of the Teton fault is asymmetric with respect to the Teton Range center, with the maximum vertical displacements (27–23 m) being located north of Jenny Lake and along the southwestern shore of Jack­son Lake. As indicated by earlier three-dimensional numerical models, this asymmetric slip distribution results from postglacial unloading of the Teton fault, which experienced loading by the Yellowstone ice cap and valley glaciers in the Teton Range during the last glaciation.

Cool deltas: Sedimentological, geomorphological and geophysical characterization of ice‐contact deltas and implications for their reservoir properties (Salpausselkä, Finland)

AbstractSediments deposited by glacial meltwaters (for example, ice‐contact delta deposits) form permeable packages in the subsurface that can act as reservoirs for both water and hydrocarbons. They are also an important source of aggregate for the construction industry. As reservoirs they are challenging to characterize in terms of their structure, flow and storage properties due to their complex depositional history. In this study, ice‐contact deltas of Salpausselkä I and II end moraines in Southern Finland are studied using a combination of geomorphological mapping, sedimentological studies and near surface geophysical methods. Sedimentary logs from isolated outcrops were correlated to ground penetrating radar (GPR) profiles to unravel the internal structure and depositional history of these ice‐contact deltas. Subsequently, electrical resistivity tomography (ERT) and gravity data were analysed to estimate the depth to bedrock and to model porosity distribution within the sediments. Results of the study suggest that the delta deposits have a broad range of porosities (10 to 42%) with lowest values found in the bottomset beds. The most variable porosities are in the subaqueous ice‐contact–fan zone, and consistently high porosities occur in delta foreset/topset facies. Detailed sedimentary logging linked to the GPR data shows heterogeneities such as mud drapes on foresets and kettle holes which are below the resolution of ERT and gravity methods but significantly affect reservoir properties of the deltas. Moreover, oscillation of the ice‐margin may have introduced larger heterogeneities (for example, buried ice marginal ridges, or eskers) into the sedimentary sequence which are atypical for other Gilbert‐type deltas. Finally, subglacially sculpted, highly variable bedrock topography exerts a major control on sediment distribution within the delta making reservoir volume and quality less predictable. This work has implications for present‐day freshwater aquifers and low enthalpy geothermal energy in southern Finland and other deglaciated regions, as well as hydrocarbon exploration of analogous deposits in the subsurface from Pleistocene and pre‐Pleistocene glaciogenic sequences.

Реконструкция масштабов и морфологических особенностей плейстоценовых оледенений на Северо-Востоке России

Based on the currently available data, it has been established that the earliest glaciations occurred in the Late Eopleistocene and at the end of the Early Neopleistocene. They had local distribution in the most uplifted parts of the Chersky Range. Their traces are presented in the form of moraines enclosed in sediments of intermontain depressions. Glacial forms of this age have not been identified in the relief of mountains and plains in the North-East of Russia. The Middle Neopleistocene glaciation was the largest, both in area and length of individual glaciers. It was mountain-valley and reticulated; in some areas, mountain-cover. Its time coincides with the stage of activation of the ascending neotectonic movements in the Middle Neopleistocene. Traces of the last two Late Neopleistocene glaciations are well expressed in the relief in widespread exaration, moraine, and fluvioglacial complexes. The first Late Neopleistocene glaciation (Zyryan) was significantly inferior to the one occurred in the Middle Neopleistocene, in all parameters, but it also left large amphitheaters of terminal moraines in the foothill belts. Glacial complexes of the last Late Neopleistocene glaciation are widespread in areas 2-3 times smaller than the previous one and, as a rule, are located within its contours.

Disentangling the stratigraphic architecture of the Rivoli-Avigliana end moraine system (Western Alps, NW Italy)

ABSTRACT The Rivoli-Avigliana end moraine system (Italian Western Alps) hosts an important stratigraphic archive of Pleistocene glaciations. A new geological map provides a 3D architecture of the system that reveals a complex architecture of glacial, alluvial and lacustrine units. Six glacial units were recognized. During the deposition of the four older glacial units (Early-Middle Pleistocene) the morphology of the valley outlet had a different drainage pattern from the present, with the presence of large lakes. From the penultimate glaciation to the Last Glacial Maximum (LGM) the piedmont lobe was confined within the valley, never extending towards the alluvial Po Plain. The LGM is characterized by two glacial advances and four distinct recessional phases during the Lateglacial. The presence of a bedrock inselberg affected the flow of the glacier front, which should have had weak erosive strength as shown by the preservation of lacustrine deposits below the glacial units.

Assessment of Morphology Changes of the End Moraine of the Werenskiold Glacier (SW Spitsbergen) Using Active and Passive Remote Sensing Techniques

Wedel Jarlsberg Land in Svalbard is a region with a varied periglacial landscape. In the mountains and in the valleys, the climate is polar with permafrost. During the summer, the near-surface ground layer thaws. The Werenskiold Glacier, together with its end moraine, are located in the central part of this area. The rate of morphological changes observed within the moraine varies in time and space, and depends on the environmental conditions. This study investigates four periods of archival aerial photogrammetry measurements (1936, 1960, 1990, and 2011) performed for the end moraine of the glacier. The long-term analysis was also based on a direct GNSS RTK survey from 2015. Over a period of almost 80 years, more than 14 million m3 of rock and ice material disappeared from the end moraine of the glacier (an average of approximately 200 thousand m3/year). Analyses of the dynamic surface changes over one year (2015) were performed with the use of synthetic aperture radar interferometry (InSAR). The time interval between images was in this case 12 days and covered (simultaneously in each scene) the entire investigated area. In this case, the analysis demonstrated that over a period of only 4 months, the moraine lost 200 thousand m3 of material (approximately two thousand m3/day), which is equivalent to the entire annual mass loss of the moraine.

Does glacial environment produce glacial mineral grains? Pro- and supra-glacial Icelandic sediments in microtextural study

Mineral grains from proglacial and supraglacial sedimentary settings in central south-eastern Iceland are considered in this study and analysed with the use of scanning electron microscope (SEM) techniques. By applying this, it is attempted to answer the key research question of whether quartz grains that come from a glacial-related sedimentary environment are indeed of glacial origin. The study also attempts to provide a linkage between microtextures produced on coarser and finer grains and to verify whether mineral grains from adjacent cryconite holes are similar or different. The preliminary assumption was that the more intense glacial grain record was based on several glacial activities from more and less recent glacial events in Iceland, and this assumption is true to some extent, because a set of sustained-shear-stress microtextures is found on coarser grains, especially in supraglacial and terminal moraine sediment samples. This latter reveals as much as 9% of glacial-type microtextures and this value seems much lower than in previous studies, which clearly argues for only limited grain glacial transformation. Glacial grains diminish with distance from a glacier, where fluvial grains dominate. Fine-grained cryoconite mineral grains reveal a proportion of glacially-induced microtextures that, nonetheless, may be a result of grain-crushing in the finer fraction. Long-distance-transported grains are practically absent in the finer fraction, likely because they are still too large to be entrained into the atmosphere. Finally, the adjacent neighbouring cryoconite holes reveal a different set of grain types, meaning that every cryoconite hole is independent and its grain type might be very random.

Subglacial squeeze-up moraines adjacent to the Vaalajärvi-Ristonmännikkö glacially-induced fault system, Finnish Lapland

The Vaalajärvi-Ristonmännikkö glacially induced fault (GIF) system in central Finnish Lapland is attributed to multiple slip events (Mw ≈ 6.7–7.0 earthquakes), likely contributing to subglacial and postglacial sediment deformations. We applied light detection and ranging digital elevation models (LiDAR DEMs), electrical-sedimentary anisotropy (orientation) measurements and trenching to study the related geomorphology, particularly subglacial moraines on the hanging wall of the Ristonmännikkö GIF segment striking SW-NE direction. Transverse-to-ice-flow-oriented moraines and the Pulju moraines were found to cover the distal tails of the Early Weichselian rock-drumlins and they are interpreted as seismically induced crevasse infill landforms. The electrical-sedimentary anisotropy suggests squeeze-up origin rather than active ice oscillation end moraine formation processes. Based on our recent OSL-data, the squeeze-up moraines are also superimposed on a till-covered esker system yielding an age of 87 ka. Erosional V-shaped features with apices pointing up-ice were found on convex surfaces of the distal rock-drumlin tails and were attributed to subglacial mass-flows rather than glaciofluvial erosion or frozen bed fracturing mechanisms. The area lacks glaciofluvial/hummocky corridors, but a substantial outburst system on the streak of Ristonmännikkö GIF suggests an earthquake-triggered outburst of the former subglacial Lake Unari. Our recent 14C ages of paleolandslides suggest that the Vaalajärvi-Ristonmännikkö GIF terrain was ice-free already 11.3 cal kyr BP, but was subjected to lithospheric water discharge and landslide events at 2.9 and 10.6 cal kyr BP. The squeeze-up moraines most likely formed during the later phase of the Younger Dryas, between ca. 12.0–11.5 cal kyr BP. We propose that subglacial seismicity within a glacial isostatic adjustment (GIA) environment was a notable trigger for the squeeze-up and mass-flow features beneath the retreating Fennoscandian Ice Sheet (FIS) during the later phase of the Younger Dryas.

Quantifying short-range variation of soil texture and total carbon of a 330-ha farm

We quantified the short-range variation (<5 m) of soil texture and total carbon at a 330-ha arable farm in Wisconsin, USA. The farm is located in a young landscape (<12 ky), and geomorphic units include unglaciated parts, outwash plain, end moraine, and a former lacustrine bed. At 100 locations, three soil cores, in a 90-cm triangle configuration, were collected to 90-cm depth. The soil cores were subsampled at 10-cm depth interval (total 2,241 samples). Clay, sand, silt, and total carbon were predicted for all the 2,241 samples using cubist spectral models developed on 25 locations (197 samples) with the vis-NIR and PXRF spectra. The coefficient of variation (CV) of each soil property was calculated for the three cores at each location and at each depth increment. The soil short-range variation was quantified for soils of the four geomorphic units. In addition, within-horizon variation (CVs) of soil properties was calculated. It was found that parent materials affected the short-range variation more than land use. Soils developed from lacustrine deposits had higher sand content and a slightly larger short-range variation for clay and silt content. Soils developed in the outwash plain had large range of CVs in the deep soil. The short-range variation and within-horizon variation were smaller in the A horizons than in the B and C horizons. The short-range variation affected the spatial structure (variograms) of the soil properties. In these young landscapes, short-range variation of soils is substantial and appropriate sampling schemes should be developed. We summarize three strategies for calculating or reducing soil short-range variation: (1) composite sampling, (2) increasing sampling density using proximal sensing instruments, (3) utilize prior information of the study area.

Physicochemical Impacts of Dust Storms on Aerosol and Glacier Meltwater on the Northern Margin of the Taklimakan Desert

To analyze the impacts of dust storms on the atmospheric and meltwater environment, intensive and simultaneous sampling for aerosols and meltwater on the terminal moraine (41°73′ N, 79°88′ E, 3,789 m a.s.l.) of Qingbingtan Glacier No. 72 (Glacier No. 72) on the northern margin of the Taklamakan Desert were conducted during the summer of 2008. Aerosol and meltwater chemistry (including the species of Na+, K+, Mg2+, Ca2+, NH4+, Cl−, SO42−, and NO3−) was analyzed by ion chromatography. The results indicated that the major anions and cations in the samples were SO42− and Ca2+, respectively. In the dust event, the average value of aerosol ions was 566.91 neq·m−3, which was nearly five times that under nondust conditions (115.58 neq·m−3). In addition, in the meltwater samples, the sum of ion concentrations ranged from 31.26 to 180.98 mg·L−1, with an average of 76.40 mg·L−1. When a dust storm occurred, the ion concentrations in these two media increased significantly and simultaneously, but with different trends due to the different influencing factors. That is, the atmospheric environment was significantly affected by the dust storm. According to the correlation analysis and principal component analysis, the water-soluble ions, such as SO42−, Cl−, Na+, K+, Mg2+, and Ca2+, originated from natural sources, while NH4+ and NO3− originated from anthropogenic sources. The results of the air mass trajectory suggested that the regional dust storms caused by the air masses originating from Eastern Europe and Siberia had a significant influence on the glacial environment.

A Brooklyn You Might Not Know

A Brooklyn You Might Not Know Ian Rocksborough-Smith (bio) Thomas J. Campanella, Brooklyn: The Once and Future City. Princeton: Princeton University Press, 2019. xiv+ 533 pp. Maps, notes, selected bibliography, and index. $35.00. Thomas J. Campanella, Brooklyn: The Once and Future City. Princeton: Princeton University Press, 2019. xiv+533 pp. Maps, notes, selected bibliography, and index. $35.00. The city of Brooklyn is often subsumed into popular depictions as one of the Big Apple's illustrious boroughs most often taken to represent the grittier aspects of New York, the "Gotham" of Batman DC Comics fame with its access to industrial waterways and suburban hinterlands. But Brooklyn has a unique regional history that sets it apart from its borough counterparts. From serving as the homeland to the Leni Lenape Algonquian peoples; to a verdant outgrowth of the Dutch colony of New Amsterdam; through various periods tied to America's expansion as a modern nation (the Revolutionary War, the Civil War, the industrializing late 19th to mid-20th centuries); to a world leader in urban architecture, reform, change and development, not to mention the erstwhile home of the Dodgers baseball team and various industries that served America's interests in World War II. Brooklyn, by Thomas J. Campanella, presents a rich tapestry of local and regional stories for any student of modern urban history to enjoy. Written with a personal gravitas, emboldened by familial attachments to a Marine Park and Italian American upbringing in the region, Campanella offers helpful historical nuance and well-cited research that allows for more sweeping analysis and bold claims about the enduring significance of what is arguably New York's most important borough. Few readers may realize how undervalued Brooklyn has been in America's urban history—despite featuring in tales of the Brooklyn Bridge, Coney Island, and gentrification of "Brownstone Brooklyn," as well as important histories of struggles to fight poverty and discrimination in Bedford-Stuyvesant (p. 2). In Brooklyn, Campanella seeks to recover elements of the most significant borough of New York in ways that are "unknown, overlooked, and unheralded" (p. 1). For example, as early as the American Civil War, Brooklyn had already passed better-known urban centers like Baltimore, Boston, New Orleans, and Cincinnati to "become the third largest city in America" (p.3). As the cover for Brooklyn suggests, the city is perhaps "America's most storied urban underdog" (cover jacket insert). And this book is not just one that challenges 20th-century [End Page 625] assumptions about Brooklyn's place in recent U.S. urban history; it is one that covers a great deal of ground from the colonial era through the present. The book features compelling vignettes of the city's modern history, such as how the Town of Gravesend was the first in the United States designed by a women; how Greenwood Cemetery was effectively New York's first public park; how Ocean Parkway became a Parisian-inspired boulevard; how racetracks, parks, and airports—all grandiose schemes of urban growth and development through the early 20th century—were also quintessentially Brooklyn phenomena. Ultimately, Brooklyn tries to chart a trajectory for the city that made it the center of "renewal" and urban development, led by giants in the field like Robert Moses, who helped unleash "the largest, most ambitious, and most devastating" projects that the country had ever seen (p. 2). Campanella argues that "Brooklyn's place spirit" formed over centuries and "around two principal fulcrums" (p. 3). The first revolved around Brooklyn's distinct landscapes and topography—a terminal moraine and outwash plain left behind by the previous Ice Age. The moraine provided elevated terrain for places like Brooklyn Heights, Park Slope, Bay Ridge, Crown Heights, and Ocean Hill. This geological depiction operates metaphorically for the author as well, because it allows one to "[m]ap the creative class in Brooklyn [and a] ghost of glacial history appear before your eyes. North of the moraine, a stone's throw from Manhattan, is the city of rapid gentrification, where elders and the poor are dislodged by implacable market forces—where even a tiny apartment now costs a king's ransom, and nothing, it seems, is not artisanal, batch...

Kamienie Zielonej Góry i przestrzenie Zielonej Góry w edukacji uniwersyteckiej (z dydaktycznych doświadczeń lit(h)olingwistki)

The lit(h)olinguistics of educational reflection focuses on stones and names relating to stones present in various open and closed spaces of the City of Magpies. It is their specificity that the students of the University of Zielona Góra explore at the interdepartamental seminar known as „Kamień w kulturze” („Stone in Culture”). The relation of space -city-stones has become an inspiration to comment on multiple stones found in Zielona Góra , among others, in: a) the landscape (terminal moraine, brown coal, lapidarium), b) secular architecture (city walls made of field stones, sidewalk, stone foundations), c) sacral architecture (medieval stone chapel in the Vineyard – „Kaplica na Winnicy”, rococo stone baptismal font), d) the museum of Zielona Góra (“disgrace” heavy stones), or e) a jeweler company (amber, pearl, brilliant). Stones that the students learn about, which spatially embellish Zielona Góra, and their names were listed and interpreted in the paper. They make the City of Wine an urban phenomenonwith stone elements of nature and culture being part of its palimpsest layers.

Predictive Mapping of Glacial and Fluvioglacial Landforms in the Nadym River Basin (North of West Siberia) With TanDEM-X DEM

Remote mapping of glacier and fluvioglacial landforms has been extensively used globally. It is supported by a range of mid-scale spatial datasets (space imaging and digital terrain models) available to the research community. Such studies are very important for the northern regions of West Siberia since the existence and scale of the Pleistocene glaciation there is still debated. Here, we use digital terrain models, multispectral images, and historical survey materials for the Nadym river basin to reveal sustainable local signs of such landforms as kames, kame (terminal) moraines, moraine and kame hilly areas, linear ridges, ancient discharge valleys, eskers, and wind-scoured basins at the fluvioglacial deposits. The mapping of the identified features showed an abundance and a great variety of glacial and fluvioglacial landforms on most of the area under consideration. Verification against the historical data confirmed the validity of identifying kames, terminal moraines, and kame hilly areas with their geology typical for the region. The results point to the primary contribution of the Pleistocene glaciation to the formation of medium and large geomorphological landforms. The proposed mid-scale geomorphological mapping strategy is also applicable to other regions of the northern part of West Siberia.

New evidence for the rank of the Wartanian cold period (Pleistocene, MIS 6): a case study from E Poland

In the stratigraphic division of the Saalian (Middle Pleistocene) in Europe, the Wartanian cold period has the rank of a stadial of the Odranian Glaciation, correlated with MIS 6. The authors demonstrate the higher rank of this cold period, on the basis of an analysis of the sedimentary succession in eastern Poland, at an exposure of the terminal moraine of the Wartanian ice sheet. At the Wólka Zagórna site, three stratigraphic units were distinguished: A (lower glacigenic deposits – glaciofluvial deposits and subglacial till), A/B (fossil soil of lessivé type), B and C (a periglacial horizon with deflation pavement, involutions, frost-wedge structures and upper glaciofluvial deposits and flow till, with ice-wedge casts). Two distinct periods of climatic cooling, associated with the youngest Saalian ice sheets, were recorded in this succession in E Poland: Odranian (unit A, an ice-sheet transgression marked by the deposition of glaciofluvial deposits dated as 365–226 ka, ending with the deposition of subglacial till), and Wartanian (units B and C, an ice sheet transgression marked by development of a periglacial zone, dated as 180–126 ka, and then deposition of glacigenic sediments at the front of the ice sheet and formation of a marginal moraine). Each of these periods of ice-sheet transgression occurred at a different time (in the MIS 8 and MIS 6 positions) and were separated by a warm period. It is documented by unit A/B – a fossil soil with a very well developed Bt horizon – which attests to its formation in an illuviation process beneath a complex of mixed forests during an interstadial warming that occurred in MIS 7. From this palaeoclimatic reconstruction, it is inferred that the Wartanian cold period should be viewed as a separate glaciation in MIS 6 and the Odranian period should be assigned to MIS 8 in the stratigraphic schema of the Quaternary.

Revised stratigraphy and palaeogeography of the Rostan Hills in northwestern Ukraine

This paper presents a new approach to stratigraphy and palaeogeography of NW Ukraine. So far, the glacial landforms near the Rostan area have been interpreted as end moraines derived from the Saalian ice-sheet. Sedimentological and petrographic analyses conducted at the Rostan site shed new light on the dynamics and age of the ice-sheet that formed the examined glaciogenic forms. Sedimentological analysis of glacial deposits documented the sedimentary environment of a glaciofluvial fan deposited by the ice-sheet front characterised by varying dynamics, i.e. advancing, stationary and retreating. Petrographic analysis proved an older age of deposits, i.e. Elsterian, and not Saalian as interpreted so far. These results shed new light on palaeogeography and stratigraphy of this area. The occurrence of the Elsterian deposits on the surface gives evidence of the absence of younger – Saalian – glaciation in this area, which relates to the recently announced new approaches to palaeogeography and stratigraphy of neighbouring areas in eastern Poland.

Sediment redistribution beneath the terminus of an advancing glacier, Taku Glacier (T'aakúKwáan Sít'i), Alaska

AbstractThe recently-advancing Taku Glacier is excavating subglacial sediments at high rates over multi-decadal timescales. However, sediment redistribution over shorter timescales remains unquantified. We use a variety of methods to study subglacial and proglacial sediment redistribution on decadal, seasonal, and daily timescales to gain insight into sub- and proglacial landscape formation. Both excavation and deposition were observed from 2003 to 2015 (2.8 ± 0.9 m a−1to +2.9 ± 0.9 m a−1). The observed patterns imply that a subglacial conduit has occupied the same site over the past decade. Outwash fans on the subaerial end moraine experience fluvial sediment reworking almost year-round, with net sediment gain in winter and net sediment loss in summer, and an overall mass gain between 2005 and 2015. We estimate that tens of meters of sediment still underlie the glacier terminus, sediments which can be remobilized during future activity. However, imminent retreat from the proglacial moraine will limit its sediment supply, leaving the moraine vulnerable to erosion by bordering rivers. Retreat into an over-deepened basin will leave the glacier vulnerable to increased frontal ablation and accelerating retreat.

Recession of Gya Glacier and the 2014 glacial lake outburst flood in the Trans-Himalayan region of Ladakh, India

This study assessed spatiotemporal changes at Gya Glacier, the associated development of a proglacial lake, and reconstructed the 2014 outburst flood that struck Gya Village in the Trans-Himalayan region of Ladakh, India. This study analyzed and for the first time modeled a Glacial Lake Outburst Flood (GLOF) event in the Trans-Himalayan region of Ladakh. Glacier and glacial lakes changes were quantified using remote sensing data supplemented with field observations. Glacier ice-thickness and glacier-bed overdeepenings were modeled using a shear-stress based model, GlabTop (Glacier-bed Topography). The reconstruction of the 2014 GLOF and the potential hazard assessment of Gya Lake were carried out using the hydrodynamic model HEC-RAS; results were validated against ground-collected data. Temporal evaluation of satellite data revealed a 45.6% loss in the total glacier area between 1969 and 2019. The earliest snow-free image available for the region shows that a proglacial lake existed as early as 1969 with an area of 3.06 ha. The lake has expanded to ~11 ha in 2019. Results from the GlabTop model suggest that the lake could grow further up to 12 ha in the future. Field-based geomorphic indicators suggest that the 2014 GLOF event resulted from a piping failure of the frontal moraine destroying numerous agricultural fields, some buildings, downstream infrastructure, and eroded natural channel embankments. The reconstruction of the event revealed that 25% of the lake waters drained out with a peak discharge of 470 m3s−1, inundating an area of ~4 km2 around Gya Village. However, a complete breaching of the terminal moraine could result in an event that would be 5.5 times larger than the 2014 GLOF. Therefore, this study could be useful not only in planning disaster-resilient infrastructure around proglacial lake environments in the cold-arid Ladakh but also in framing mitigation plans to reduce risk for vulnerable downstream communities.