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Subglacial channels are morphologically and morphometrically distinct in comparison to fluvial channels, yet their identification from remote sensing data is still problematic. To contribute to the current set of criteria used to identify such channels, we performed a detailed analysis of two subglacial channel networks on Devon Island, Nunavut, Canada. In planform, these channels are isolated, finger-like networks that drain into a main stem and have distinct cross-sectional and longitudinal profiles. Cross-sections are flat-bottomed with steep walls and longitudinal profiles are convex and exhibit undulations, typical of pressurized water flow (i.e., subglacial flow). To facilitate remote sensing identification, we interrogated how well-known scaling relationships capturing hydraulics and mass balance dynamics of fluvial systems differ in subglacial channels. Scaling relationships typically used to discern connections between discharge and channel and catchment size in fluvial systems were applied to both networks, yielding trends distinct from the fluvial literature. We suggest that the weakly correlated relationship we found between channel discharge and the size of the drainage area indicates a discrete point or line source of water, such as a moulin or crevasse. • Subglacial channels related to polythermal glaciers are morphologically distinct. • Channels form networks display longitudinal undulations and U-shape cross-section. • Fluvial scaling relationships applied for the first time to subglacial channels • Scaling relationship reveals metric indicative of lack of drainage basin. • Metric may be useful as additional diagnostic criteria for subglacial meltwater channels. [ABSTRACT FROM AUTHOR]

Ice low-switching, which can involve changes in ice flow velocity and direction, is crucial to a full understanding of ice masses and their response to climate change. A topographically controlled ice flow switch near a glacier margin was recently documented at Breiðamerkurjökull, southeast Iceland, where the central flow unit migrated eastward in response to variations in subglacial topography and the influence of Jökulsárlón glacial lagoon. This site provides an opportunity to study the geomorphic response to ice-margin reconfiguration. Investigating contemporary processes can offer valuable insights into analogous landforms created during the deglaciation of palaeo-ice sheets. The landform assemblage and topographic setting of our Icelandic study site is compared to a palaeo-example from Alberta, Canada, which was once covered by the Laurentide ice sheet. Uncrewed aerial vehicle-(UAV) derived data was used to assess the geomorphic response to this switching and related processes across a 1.5 km2 area of the central flow unit which deglaciated between 2010 and 2023. From 2010 to 2017, the landscape featured streamlined subglacial material, a stable subglacial esker system and proglacial lakes (Landsystem A), shifting to a spillway-dominated system between 2018 and 2023 (Landsystem B). Since 2018 this section of Breiðamerkurjökull has been retreating across a reverse slope bed, resulting in the formation of quasi-annual ice-marginal spillways. Meltwater impoundment at the ice margin, formed ice-contact lakes which eventually initiated ice-margin parallel spillways draining proglacial meltwater along the local land-surface gradient, towards Jökulsárlón. As the ice retreats, an ice-contact lake forms again at the new margin and initiates the erosion of the next ice-marginal spillway. The geomorphological signature demonstrates how subglacial topography and ice-flow switching can significantly influence ice and meltwater dynamics. Since the glacier flow-switch, part of the central unit is now lake-terminating with areas of the margin evolving into a stagnant system, as it is now cut off from the accumulation centre. Therefore, Landsystem B could be analogous to regions of ice stream shut down and where ice masses retreated across reverse slope beds. For example, the Pakowki Lake region of Southeastern Alberta displays a similar landform assemblage and is presented as a palaeo-example in this work. Such insights are important for assessing the efficacy of numerical models in reconstructing the finer scale dynamics of past ice sheets during retreat. • Landform mapping at Breiðamerkurjökull (Iceland) from UAV-derived data reveals two distinct landform assemblages. • Landsystem A (2010-2017): flat subglacial bed, subglacial eskers and proglacial lakes. • Landsystem B (2018-2023): reverse slope bed and ice-marginal spillways. • Landsystem B is analogous to SE Alberta, providing support for existing spillway reconstructions in the region. • The geomorphic response highlights the significance of subglacial topography on ice and meltwater dynamics. [ABSTRACT FROM AUTHOR]

Large-scale landforms originated from jökulhlaups or glacial lake-outburst floods (GLOFs), and their small-scale components help in recognising the sedimentary environment of the flood. The GLOF fans that developed along the Pleistocene ice-sheet margin have not been investigated in detail, and north-eastern Poland, with its Megaflood Landform System and Bachanowo and Szeszupka fans, seems ideal for landform and sedimentary studies. This paper provides (1) an important opportunity to recognise the origins of glacier lake-outburst flood outlets and their evolution during two GLOFs and (2) a model of the origin of ice-marginal fans considering changes in sedimentary environment reflecting flood stages. During the first GLOF (GLOF1), the rising stage of meltwater burst triggered the formation of a supraglacial outlet and the development of the Szeszupka outburst fan. During the pulsed peak discharge, subglacial multi-channelised meltwater outburst caused the formation of the Bachanowo Gate, which was finally transformed at the flood waning stage. Such processes were associated with the widening of the floodwater subglacial routeway, when floodwater outlets rapidly spread across the glacier snout. In contrast, GLOF2 was responsible only for the Szeszupka fan erosion and development of outburst terraces. The small-scale bedforms continuum, recognised on the outburst fan surface, is associated with the development of streamlined erosional residuals, scours and their trains during the rising stage and peak discharge, while the waning stage and very end of flood conditions were favourable to the formation of pendant bars, distributive channels with erosional bars and chute bars, regardless of the feeding systems of the outburst fans. The fan deposits were OSL-dated and revealed either, likely, overly old ages or an age of 13.2 ± 0.9 ka. The latter age would imply the 'normal' meltwater outflow having a correlation with the events in the region. Nevertheless, this age might be considered a minimum age of the flood. • Supraglacial outlet developed first due to hydrofracturing during the rising GLOF stage. • The second outlet started to form at the peak discharge due to subglacial multi-channelized drainage. • The dominant processes in outburst fan formation are riverbed scouring and subsequent sediment deposition. • The small-scale bedform continuum evolved on outburst fan surface in relation to GLOF stages. • Outburst fan deposits were OSL-dated and revealed too old ages or an age of 13.2 ± 0.9 ka. [ABSTRACT FROM AUTHOR]

Within mountainous landscapes neighboring glaciers, slope instabilities and consequent catastrophic mass flows are vital processes on Earth's surface, which have been of increasing interest for decades. These events commonly exhibit large volume, high velocity, and high mobility. Recently, a catastrophic debris flow occurred in India on 7 February 2021, which unfortunately claimed 70 lives and left 134 people missing. The failed mass comprises 80 % rock debris and 20 % glacier ice. Our remote sedimentological investigation of remnant deposition shows clear evidence of wet granular flow in upper Ronti Gad valley, which doesn't support the previous interpretation of immediate melting of the failed 20 % ice mass during the falling and impacting process. We further utilized the superelevation phenomenon to back-calculate the velocity downstream of the impact zone, and estimated the peak discharge, which is verified by field-documented data. Our results revealed an initial waning trend of rock and ice mass flow. As it entered the narrow valley of the lower Ronti Gad River, the extensive material erosion resulted in three-fold flow enlargement, which gave rise to a maximal peak discharge of up to 48–54 × 104 m3/s. The transition from granular flow to debris flow occurred in the 2-km-long channel downstream of the Ronti Gad-Rishigangga confluence. The sediment deposition of 4.8 × 104 m3 and the incorporation of stream water in this zone have dominated the rheologic transition. We inferred that the intense erosion of erodible sediment due to topographic constraint plays an essential role in maintaining the mobility of the flow. Therefore, the effect of glacier ice meltwater on high mobility may be overestimated. As long as the granular flow can access the stream water in major rivers, flow transformation can easily happen because of sufficient water supply in the channel. The valley morphology in the proglacial region is commonly featured by the shift from an upstream U-shaped valley carved by glacier erosion into a downstream fluvial-erosion-dominated V-shaped valley. This geomorphic setting of glaciated tributary favors the long-distance run-out of rock and ice avalanche. • Material erosion due to valley confinement enlarged Chamoli mass flow • The effect of glacier ice meltwater on high mobility may be overestimated. • The proglacial geomorphic setting favors high mobility of rock-ice avalanche. [ABSTRACT FROM AUTHOR]

Elongated tracts of hummocks or 'hummock corridors', exposed on palaeo-ice sheet beds, are believed to represent former subglacial meltwater pathways. Here, we present a method, coded in MATLAB, for automatically detecting and mapping hummock corridors from high-resolution digital elevation models (DEMs). Initially the DEM is filtered to remove bed roughness outside the size range of hummocks. A Fast Fourier Transform is then performed to determine the dominant orientation of hummock corridors and remove misaligned features. Finally, image segmentation is used to isolate and extract the hummock corridors as a binary mask. The automated approach is tested visually and statistically against detailed manual mapping in three areas of Canada and northern Scandinavia. Results show that while the automated method does not perfectly reproduce the manual mapping, it successfully captures the general configuration, morphometry (length and width) and location of hummock corridors, despite variation in expression across and between sites. This technique is ideally suited to take advantage of newly available high-resolution digital elevation data (e.g. the ArcticDEM), whose enormous volume makes large-scale manual mapping prohibitively time consuming. Its application will enable efficient and comprehensive mapping of the spatial distribution of hummock corridors across palaeo-beds that is necessary for deriving insights into their formation and the organisation of subglacial meltwater flow beneath ice sheets. • Elongated tracts of hummocks or 'hummock corridors' on palaeo-ice sheet beds represent former subglacial meltwater paths. • We develop a method that isolates hummock corridors from high-resolution DEMs using image processing techniques. • The method rapidly approximates the large-scale pattern of hummock corridors at an ice-sheet scale. • Resulting information can be used to gain insight into the nature and evolution of subglacial meltwater drainage. [ABSTRACT FROM AUTHOR]

Abstract Proglacial systems are enlarging as glacier masses decline. They are in a transitory state from glacier-dominated to hillslope and fluvially-dominated geomorphological processes. They are a very important meltwater, sediment and solute source. This study makes the first quantitative, systematic and regional assessment of landform composition and functioning within proglacial systems that have developed in the short term since the Little Ice Age (LIA). Proglacial system extent was thus defined as the area between the LIA moraine ridges and the contemporary glacier. We achieved this assessment via a series of topographic analyses of 10 m resolution digital elevation models (DEMs) covering the central European Alps, specifically of Austria and Switzerland. Across the 2812 proglacial systems that have a combined area of 933 km2, the mean proportional area of each proglacial system that is directly affected by glacial meltwater is 37%. However, there are examples where there is no glacial meltwater influence whatsoever due to complete disappearance of glaciers since the LIA, and there are examples where >90% of the proglacial area is probably affected by glacial meltwater. In all of the major drainage basins; the Inn, Drava, Venetian Coast, Po, Rhine, Rhone and Danube, the proportions of the combined land area belonging to each landform class is remarkably similar, with >10% fluvial, ~35% alluvial and debris fans, ~50% moraine ridges and talus/scree, and ~10% bedrock, which will be very helpful for considering estimates of regional sediment yield and denudation rates. We find groupings of the relationship between proglacial system hypsometric index and lithology, and of a slope threshold discriminating between hillslope and fluvial-dominated terrain, both of which we interpret to be due to grain size. We estimate of contemporary total volume loss from all of these proglacial systems of 44 M m3a−1, which equates to a mean of 0.3 mm·a−1 contemporary surface lowering. Overall, these first quantifications of proglacial landform and landscape evolution will be an important basis for inter- and intra-catchment considerations of climate change effects on proglacial systems such as land stability, and changing water, sediment and solute source fluxes. Our datasets are made freely available. Highlights • Delineation of 2812 proglacial systems in central European Alps of total 933 km2 • Glacier meltwater and landform coverage spatially discriminated for each system • Lithological control evident in slope threshold – contributing area analysis • First order estimate of total contemporary volume loss = 44 M m3a−1 [ABSTRACT FROM AUTHOR]

A subglacial drainage network underneath the paleo-ice sheet off West Greenland is revealed by a new compilation of high-resolution bathymetry data from Melville Bay, northeast Baffin Bay. This drainage network is an indicator for ice streaming and subglacial meltwater flow toward the outer shelf. Repeated ice sheet advances and retreats across the crystalline basement together with subglacial meltwater drainage had their impact in eroding overdeepened troughs along ice stream pathways. These overdeepenings indicate the location of a former ice sheet margin. The troughs inherit characteristics of glacial and subglacial meltwater erosion. Most of the troughs follow tectonic weakness zones such as faults and fractures in the crystalline bedrock. Many of these tectonic features correspond with the orientations of major fault axes in the Baffin Bay region. The troughs extend from the present (sub) glacial fjord systems at the Greenland coast and parallel modern outlet-glacier pathways. The fast flowing paleo-ice streams were likely accelerated from the meltwater flow as indicated by glacial landforms within and along the troughs. The ice streams flowed along narrow tributary troughs and merged to form large paleo-ice streams bedded in the major cross-shelf troughs of Melville Bay. Apart from the troughs, a rough seabed topography characterises the bedrock, and we see a sharp geomorphic transition where ice flowed onto sedimentary rock and deposits. [ABSTRACT FROM AUTHOR]

The rerouting of meltwater as the configuration of ice sheets evolved during the last deglaciation is thought to have led to some of the most significant perturbations to the climate system in the late Quaternary. However, the complex pattern of ice sheet meltwater drainage off the continents, and the timing of rerouting events, remains to be fully resolved. As the Laurentide Ice Sheet (LIS) retreated north of the Adirondack Uplands of northeastern New York State during the last deglaciation, a large proglacial lake, Lake Iroquois, found a lower outlet that resulted in a significant flood event. This meltwater rerouting event, from outflow via the Iro-Mohawk River valley (southern Adirondack Mountains) to the spillway at Covey Hill (northeastern Adirondack Mountains), is hypothesized to have taken place ~ 13.2 ka and disturbed meridional circulation in the North Atlantic Ocean. However, the timing of the rerouting event is not certain because the event has not been directly dated. With improving the history of Lake Iroquois drainage in mind, we obtained cosmogenic 10 Be exposure ages on a strath terrace on Moss Island, along the Iro-Mohawk River spillway. We hypothesize that Moss Island's strath terrace became abandoned during the rerouting event. Six 10 Be ages from the strath surface average 14.8 ± 1.3 ka, which predates the previously published bracketing radiocarbon ages of ~ 13.2 ka. Several possibilities for the discrepancy exist: (1) the 10 Be age accurately represents the timing of a decrease in discharge through the Iro-Mohawk River spillway; (2) the age is influenced by inheritance. The 10 Be ages from glacially sculpted surfaces on Moss Island above the strath terrace predate the deglaciation of the site by 5 to 35 ky; and (3) the abandonment of the Moss Island strath terrace relates to knickpoint migration and not the final abandonment of the Iro-Mohawk River as the Lake Iroquois spillway. Further study and application of cosmogenic 10 Be exposure dating in the region may lead to tighter chronologic constraints of meltwater history of the LIS. [ABSTRACT FROM AUTHOR]

High-resolution digital topographic data permit morphological analyses of glacial processes in detail that was previously infeasible. High-level glaciofluvial erosional scars in central Pennsylvania, identified and delimited using LiDAR data, define the approximate ice depth during a pre-Wisconsin advance, > 770,000 BP, on a landscape unaffected by Wisconsin glaciation. Distinctive scars on the prows of anticlinal ridges at 175–350 m above the valley floor locate the levels of subice meltwater channels. A two-component planar GIS model of the ice surface is derived using these features and intersected with a digital model of contemporary topography to create a glacial limit map. The map is compared to published maps, demonstrating the limits of conventional sediment-based mapping. Additional distinctive meltwater features that were cut during deglaciation are modeled in a similar fashion. [ABSTRACT FROM AUTHOR]

Proglacial systems are amongst the most rapidly changing landscapes on Earth, as glacier mass loss, permafrost degradation and more episodes of intense rainfall progress with climate change. This review addresses the urgent need to quantitatively define proglacial systems not only in terms of spatial extent but also in terms of functional processes. It firstly provides a critical appraisal of prevailing conceptual models of proglacial systems, and uses this to justify compiling data on rates of landform change in terms of planform, horizontal motion, elevation changes and sediment budgets. These data permit us to produce novel summary conceptual diagrams that consider proglacial landscape evolution in terms of a balance of longitudinal and lateral water and sediment fluxes. Throughout, we give examples of newly emerging datasets and data processing methods because these have the potential to assist with the issues of: (i) a lack of knowledge of proglacial systems within high-mountain, arctic and polar regions, (ii) considerable inter- and intra-catchment variability in the geomorphology and functioning of proglacial systems, (iii) problems with the magnitude of short-term geomorphological changes being at the threshold of detection, (iv) separating short-term variability from longer-term trends, and (v) of the representativeness of plot-scale field measurements for regionalisation and for upscaling. We consider that understanding of future climate change effects on proglacial systems requires holistic process-based modelling to explicitly consider feedbacks and linkages, especially between hillslope and valley-floor components. Such modelling must be informed by a new generation of repeated distributed topographic surveys to detect and quantify short-term geomorphological changes. [ABSTRACT FROM AUTHOR]

The importance of ice cliffs for glacier-scale ablation on debris-covered glaciers is now widely recognised. However, a paucity of data exists to describe the spatio-temporal distribution of ice cliffs. In this study we analysed the position and geometry of 8229 ice cliffs and 5582 supraglacial ponds on 14 glaciers in the Everest region between 2000 and 2015. We observed notable ice cliff and pond spatial coincidence. On average across our study glaciers, 77% of supraglacial pond area was associated with an adjacent ice cliff, and 49% of ice cliffs featured an adjacent supraglacial pond. The spatial density of ice cliffs was not directly related to glacier velocity, but did peak within zones of active ice. Furthermore, we found that ice cliff density was glacier-specific, temporally variable, and was positively correlated with surface lowering and decreasing debris thickness for individual glaciers. Ice cliffs predominantly had a north-facing (commonly north-westerly) aspect, which was independent of glacier flow direction, thereby signifying a strong solar radiation control on cliff evolution. Independent field observations indicated that cliff morphology was related to aspect, local debris thickness, and presence of a supraglacial pond, and highlighted the importance of surface runnel formation, which acts as a preferential pathway for meltwater and debris fluxes. Overall, by coupling remote sensing and in-situ observations it has been possible to capture local and glacier-scale ice cliff dynamics across 14 glaciers, which is necessary if explicit parameterisation of ice cliffs in dynamic glacier models is to be achieved. [ABSTRACT FROM AUTHOR]

High-Arctic terrestrial slopes have received limited systematic research interest, but increased vulnerability related to regional warming has driven the call for better knowledge of the dynamics of these systems. Studies of sediment transport from a plateau area in Adventdalen, Svalbard, and associated slopes extending to sea level demonstrate that glacial processes play a more prominent role than earlier anticipated, − especially the impact of glacial meltwater. Traces of drainage at the plateau and the dissection of the plateau edge and upper slope were clearly initiated during various stages of Late Glacial runoff. Further, there is a close association between the sediment distribution and composition at the plateau and the evolution of various types of slopes. The reconstructed sedimentation history shows that the landscape will undergo four stages with contrasting modes of sediment transport: 1) subglacial processes related to active ice, 2) processes related to the margin of active ice, 3) processes related to the melting of inactive ice, and 4) nonglacial processes. These stages form four successions, referred to as supply regimes A–D , which control the supply of water and sediments to a given slope segment. In this landscape, traces of glacial meltwater occur at most altitudes, in “odd” positions and in slope segments “without” catchments. The associated depocenters (isolated, composite or coalescing into aprons), are often outsized compared to the apparent slope catchment. Reworked glacial sediments form a significant part of the slope-debris but are covered partly or entirely by products of physical weathering. Colluvium, senso stricto , thus masks a distinct system shift related to the local termination of glacial meltwater. Consequently, the weathering part of the slope sediment budget in this region is considerably overestimated. [ABSTRACT FROM AUTHOR]

On July 3, 2022, at 13:43:20 CEST (11:43:20 UTC), a mass of about 64,000 t of water, ice, and rock debris broke off from the Marmolada Glacier in the Dolomites (Northeastern Italian Alps), forming an ice avalanche that killed 11 mountaineers and injured 7 after flowing for about 2.3 km along the slope. The collapse occurred on the northern slope at an elevation of 3213 m above sea level and involved a major portion of a small isolated glacier. This small glacier was part of the glacial front until about a decade ago, and today, because of the fragmentation caused by the retreat, it remains isolated and contained within a niche on the north-facing slope just below the crest. The event was documented by several videos recorded by hikers who were at the site, which helped in the analysis of the causes. The seismic energy released by the event was comparable to an earthquake of 0.6 M. The detailed analysis of pre- and post-event stereoscopic satellite and aerial images led to a comprehensive insight on the failure. The detachment was largely caused by a failure along a median crevasse partly filled by a huge volume of meltwater induced by highly anomalous late spring and early summer temperatures that reached 10.7 °C at the time of the event. The dense pattern of crevasses along with the morphology and properties of the basal rock surface predisposed to failure, which was finally driven by the overpressure caused by the excess of melting water. A combination of hydraulic jacking and buoyant pressure within a thin layer of basal till were probably the two mechanisms that caused instability resulting ultimately in the sudden glacier collapse. [ABSTRACT FROM AUTHOR]

Glacial landforms provide invaluable information on the dynamics and extent of past ice sheets. In planform view, murtoos are triangular-shaped subglacial landforms that have recently been described from areas previously covered by the Fennoscandian Ice Sheet and whose formation has been linked to meltwater activity. We document the first occurrence of offshore murtoos and associated eskers in a high-resolution multibeam and sub-bottom profile dataset from the northern Gulf of Riga, Baltic Sea. In this study area, the murtoos appear to be longer (range 43–748 m), narrower (range 12–394 m) and less high (range 0.5–7.8 m), on average, compared to those previously reported on land, although this may be partly due to post-glacial sediments that smooth the present-day seafloor topography and may have buried smaller murtoos. The direction of murtoo longitudinal axes suggests a local NNE–SSW paleo-ice stream direction. In sub-bottom boomer profiles, the murtoos are characterized by moderate amplitude, sub-parallel discontinuous internal reflectors, indicating a varying sandy diamicton and sand composition, which is compatible with the previously interpreted mode of deposition by pulsed subglacial meltwater flow. Eskers that are found in close association with the murtoos are shorter (mean length 538 m) and more curved than their counterparts on nearby land areas, and they lack a general alignment. In boomer profiles, the eskers are characterized by low-amplitude, sub-parallel continuous reflectors, suggesting a better-sorted sandy composition. The curved and poorly aligned external form of the eskers suggests deposition under restricted subglacial drainage conditions. We conclude that murtoos and related landforms in the northern Gulf of Riga were formed during the Bølling warming at ca. 14.5–14.1 cal kyr BP, when large amounts of meltwater were delivered to the ice-sheet bed. • The first discovery of murtoos in an offshore multibeam dataset • The murtoos likely formed during the Bølling warming at ca. 14.5–14.1 cal kyr BP. • The murtoo longitudinal axis direction suggests a NNE–SSW paleo-ice stream direction. [ABSTRACT FROM AUTHOR]

Anthropogenic climate change threatens water storage and supply in the periglacial critical zone. Rock glaciers are widely distributed alpine aquifers with slower response to temperature increases, that provide the summer water flow of many alpine streams. Knowing the extent and makeup of rock glaciers is necessary to evaluate their potential for water supply. We used non-invasive methods, integrating geological, geomorphological, meteorological, and geophysical information to characterize the internal structure and hydrology of the Upper Camp Bird rock glacier (UCBRG) located on level 3 of Camp Bird Mine in Ouray, Colorado, and assessed the applicability of two electromagnetic induction systems in this highly heterogeneous landform with a history of anthropogenic activity. The time-domain (G-TEM™) system achieved deep subsurface penetration (~100 m) and realistic modeling of the internal structure of the UCBRG: a shell of volcanic rock fragments (<3 m thick; 1–100 Ohm-m), a meltwater component (102–103 Ohm-m), located between 50 and 100 m near the toe (subpermafrost flow), and 1–30 m in the soundings farthest from the toe (suprapermafrost flow within the active layer), and a frozen component (permafrost 50–80 m thick; 103–106 Ohm-m). The frequency-domain system, however, was highly susceptible to local environmental conditions, including anthropogenic objects (i.e., mine carts, lamp posts, tunnel tracks, etc.) and was unable to resolve UCBRG's internal makeup. The non-invasive methodology and general conceptual framework presented here can be used to characterize other alpine aquifers, contributing to the quantification of global water resources, and highlighting the importance of preserving rock glaciers as storage for critical water supply in the future. • We use non-invasive methods including electromagnetic induction (EM) to determine the internal structure of a rock glacier • We assess the applicability of two controlled-source EM systems (TDEM and FDEM) on a highly heterogeneous landform • The TDEM system is adequate to map the distribution of the electrical resistivity at depth (up to 100 m) • The principles are not satisfied to compute the apparent conductivity from FDEM data [ABSTRACT FROM AUTHOR]

A paucity of research exists regarding the millennial-scale response of inland alluvial streams to abrupt base-level fall. Studies of modern systems indicate that, over short time scales, the response is a diffusion-like process of upstream-propagating incision. In contrast, evidence from the lower Chippewa River (LCR), located in the upper Midwest of the USA, suggests that autogenic controls operating over time scales of several millennia can overwhelm diffusion, resulting in incision that is prolonged and episodic. During the Last Glacial Maximum, the LCR drained the Chippewa Lobe of the Laurentide Ice Sheet to the glacial upper Mississippi River (UMR). As a meltwater stream, it aggraded and filled its valley with glacial outwash, as did its largest tributaries, which were also meltwater streams. Its nonglacial tributaries aggraded, too, filling their valleys with locally derived sediment. During deglaciation, the UMR incised at least twice, abruptly lowering the LCR's base level — ~ 15 m at 16 ka or earlier and an additional 40 m at ca. 13.4 ka. Each of these base-level falls initiated incision of the LCR, led by upstream migrating knickpoints. The propagation of incision has, however, been a lengthy process. The optically stimulated luminescence (OSL) ages of terrace alluvium indicate that, by 13.5 ka, incision had advanced up the LCR only 15 km, and by 9 ka, only 55 km. The process has also been episodic, resulting in the formation of fill-cut terraces (inferred from GPR surveys and exposures of terrace alluvium) that are younger and more numerous in the upstream direction. Autogenic increases in sediment load and autogenic bed armoring, the result of periodic tributary-stream rejuvenation and preferential winnowing of fines by the incising river, may have periodically caused knickpoint migration and incision to slow and possibly stop, allowing lateral erosion and floodplain formation to dominate. A decline in sediment flux from stabilizing incised tributary stream systems would have led to renewed knickpoint migration and incision when floods of sufficient magnitude to breach the channel armor occurred. Minimal floodplain development along the upper section of the present-day LCR, along with the channel morphology of an unstable wandering gravel-bed river immediately downstream from it, suggest that the river is still responding to the base-level falls that happened many millennia ago. The autogenic controls on the LCR's response to UMR incision are a direct consequence of the thick fills of noncohesive sediment that accumulated in its valley and the valleys of its tributary streams during the Late Wisconsinan, making the LCR a prime example of a former proglacial river that remains a paraglacial fluvial system. [ABSTRACT FROM AUTHOR]

The decay of the Laurentide ice sheet southern margin during the last deglaciation led to the development of Lake Ojibway that covered large expanses of northeastern Ontario and northwestern Quebec. The history of Ojibway lake phases is poorly detailed mainly because of the physical configuration of the lake basin and the dominance of fine-grained glaciolacustrine sediments that prevent the formation of well-developed and extensive sandy strandlines. Here we use a complex sequence of relict terraces carved in glaciolacustrine rhythmites to document the evolution of Lake Ojibway in northwestern Quebec. Specifically, lake levels were constrained by measuring the elevation of 154 raised wave-cut scarps present in the eastern Lake Abitibi region. Results provide evidence for four distinct shorelines with elevations of 299, 289, 282, and 272 m (± 1 m) at the latitude of La Sarre. The highest lake level documented appears to be linked to one of the two known (Kinojévis) phases of Lake Ojibway, while the three other lake levels project well below the main outlet system that controlled the elevation of the lake during the deglaciation. The elevation, uplift gradients, and areal extent of these lower shorelines suggest that the two intermediate lake levels likely formed during late stages of the deglaciation, following abrupt drawdowns of the lake's surface. The fourth and lowest shoreline is associated with a postglacial lake that developed after the complete withdrawal of Ojibway water from the region. These low-elevation shorelines bring new evidence for significant changes in the areal extent and depth of Lake Ojibway near the end of the deglaciation. Although the origin of these late-stage phases remains unspecified, the associated drawdowns likely implied routing events into newly deglaciated regions and/or (subglacial) meltwater discharges into the North Atlantic. [ABSTRACT FROM AUTHOR]

The glaciers of the Torngat Mountains of northern Labrador are the southernmost of the Canadian Arctic and the easternmost of continental North America. Currently, 195 small mountain glaciers cover an area in excess of ~ 24 km 2 , confined mostly to small cirques and upland depressions. Using a combination of field and remote sensing methods this study reconstructs and dates the areal extent of Torngat glaciers at their Neoglacial maximums, enabling the first assessment of regional glacier change over the past several centuries. Mapped glacier paleomargins (n = 165) are compared to current (2005) glaciers and ice masses, showing a 52.5% reduction in glacier area, with at least 11 former glaciers altogether disappearing. Glacier change is spatially homogenous and independent of most geographic and topographic factors; however, glacier elevation and glacier size mitigated total change. Previously established lichen growth stations were revisited, and growth rates recalculated based on ~ 30-year-long records, enabling the construction of locally derived low- and high-altitude lichen growth curves. Using growth rates and in situ lichen measurements, the retreat from maximum Neoglacial moraine extents are suggested to have occurred between A.D. 1581 and 1673. These findings indicate a similar magnitude of post-LIA retreat to mountain glaciers elsewhere, yet a much earlier timing (~ 200 years) of retreat than other glaciers in the eastern Canadian Arctic. Though no definitive answer explaining this discrepancy is presented, evidence suggests that regional climate dynamics and the importance of solar radiation for Torngat glaciers may play an important role in local glacierization. [ABSTRACT FROM AUTHOR]

Eberswalde crater, Mars, contains a well-preserved fluvial distributary network in a likely deltaic setting. The meandering inverted paleochannels and closed drainage basin of this deposit support relatively well constrained estimates of channel-forming discharge (over an individual event flood timescale), runoff production (event and annual timescales), and longevity of deposition (geologic timescale) during the Late Hesperian to Early Amazonian Epochs. The width and meander dimensions of two inverted paleochannels reflect the channel-forming discharge from event floods (~ 200 to 400 m 3 /s), the deposit surface indicates the level (− 1400 to − 1350 m) and surface area (410 to 810 km 2 ) of the likely paleolake, and the topography and mapped extent of tributaries constrain the watershed area (5000 to 17,000 km 2 ). Based on these results and terrestrial empirical constraints on evaporation and sediment concentration, we evaluated three hypothetical water sources: meltwater liberated by the nearby Holden crater impact (continuous deposition over ~ 10 1 –10 2 years), intermittent rainfall or snowmelt during finite periods controlled by orbital evolution (deposition over ~ 10 4 –10 6 years), and highly infrequent runoff or melting of accumulated snowpacks following distant impacts or secular changes in orbital parameters. Local impact-generated runoff and highly infrequent rainfall or snowmelt require unreasonably high and low rates of evaporation, respectively, to maintain the paleolake level. The local impact hypothesis alternatively depends on one flooding episode with very high concentrations of fluvial sediment that are inconsistent with morphologic considerations. Multiple primary impact craters in the area postdate Holden ejecta but were later dissected, indicating fluvial erosion long after the Holden impact. Intermittent rainfall of ~ 1 cm/day and seasonal snowmelt are both consistent with our results over a deposition timescale totaling ~ 10 4 –10 6 years. [ABSTRACT FROM AUTHOR]

Mongolia's cryosphere is relatively poorly studied; this review sheds light on the research on paleoglaciations, recent glaciers, and permafrost. Historical works mostly added to reconstructions of paleoglaciations and the development of geochronologies that are increasingly based on numerical dating methods including the use of cosmogenic radionuclides. During the Pleistocene, four glaciation centers existed: Altai, Eastern Sayan, Khangai, and Kenthii mountains. Pleistocene glaciations covered an area of between 20,000 and 30,000 km2 and occurred partly asynchronously across these mountain systems: the glacier maximum in the Altai, Khangai, and Eastern Sayan occurred during MIS 3, while it occurred during MIS 2 in the Khentii and Gobi Altai. Today, Mongolia's glaciers are restricted to the Altai and generally in recession for the past decades; the total glacial area decreased by 35% from 1990 to 2016, when 627 glaciers covered 334 km2. In the Upper Khovd River Basin that includes Tavan Bogd, Mongolia's recent glaciation center, the contribution from meltwater to total runoff decreased by >3% from 2000 to 2016. The Altai glaciers are predicted to undergo sustained mass loss by 2100, with some locations, particularly in the western Altai, losing all their ice. Uncertainties about the occurrence and distribution of permafrost still exist as subtype classifications vary, periglacial conditions might have been interpreted as permafrost, and not all researchers agree on the existence of continuous permafrost within Mongolia. Today, permafrost covers 26% of Mongolia's territory. Undoubtedly, permafrost warming and thawing is widespread, and the ground ice is predicted to disappear in the 21st century. Climate change already left its mark on Mongolia's cryosphere and consequently on many communities. Hence, sustainable approaches are needed in water resources management in the Altai and technical infrastructure maintenance and improvement in permafrost regions. • Glaciations existed in four mountain systems and occurred partly asynchronously. • Today, glaciers are restricted to the Altai and generally in recession. • Permafrost occurs 1/4 of the territory and is warming and thawing in many locations. • Climate change has negative effects on water resources and infrastructure. [ABSTRACT FROM AUTHOR]

Fluctuations in meltwater discharge below modern glaciers and ice sheets due to diurnal, seasonal and long-term temperature variations are modulated by complex interactions between subglacial drainage, basal processes and bedform development. The bed of palaeo-ice sheets contains a variety of bedforms recording these modulations and provides an open window into the subglacial environment. Through the morphometric analysis of natural and experimental bedforms, respectively mapped along Scandinavian meltwater corridors and produced in a physical model simulating transitory subglacial water flow, we observe a morphological and genetic bedform continuum corresponding to the progressive transformation of ribbed bedforms into murtoos. Two alternating drainage configurations, related to repeated subglacial flooding events, are involved in this transformation: (i) significant meltwater discharge, high hydraulic connectivity and ice-bed decoupling during flooding events lead to hydraulic alteration of ribbed bedforms by erosion, sediment deposition and channel incision, while (ii) limited meltwater flow, low hydraulic connectivity and ice-bed recoupling that follow flooding events lead to their deformational reshaping into murtoos. The degree of transformation of ribbed bedforms into murtoos can be quantified by combining two dimensionless morphometric parameters (circularity and sinuosity) and provides a convenient proxy to constrain magnitudes, durations and/or frequencies of subglacial floods in palaeo-meltwater corridors. • High resolution mapping of ribbed bedforms and murtoos in Sweden and Finland • Modelling reproduces murtoos by erosion/deposition/deformation of ribbed bedforms • New morphometric parameters show a bedform continuum illustrating the transformation of ribbed bedforms into murtoos • This continuum reveals subglacial drainage reorganization during repeated flooding • We provide key criteria to constrain magnitudes, durations and frequencies of subglacial floods in palaeo-meltwater corridors [ABSTRACT FROM AUTHOR]

Abstract: Glacial surges are periods of fast flow, often limited in space and time, and driven by internal conditions which are not fully explained. The quantity and variety of documented case-studies and settings demonstrate that the critical variables are difficult to isolate. In an alternative approach, two surges from the same basin were compared at Fridtjovhamna; one of the few known sites where this is possible. Fridtjovbreen is a polythermal glacier that has been through two recent surges: the last event (1991–2002) occurred during an unusually warm period in the high Arctic, whereas the previous surge culminated in 1861, around the Little Ice Age when many Svalbard-glaciers had their maximum Holocene extent. Based on a multi-disciplinary study, processes and landforms from the two episodes were compared with respect to ice-front movement rates, formation and decay of ice-cored moraines and glacial meltwater drainage patterns. The study demonstrates that moraines and meltwater traces from the oldest surge, locally well preserved, provide excellent opportunities for reconstructing the behavior of the ice-mass. The last surge, however, took place during a period with ablation rates never seen at this latitude, and 10years after the maximum extent, the deglaciated areas onshore hardly show traces from the event. [Copyright &y& Elsevier]

In this study, depositional conditions in the glaciogenic Champlain Sea basin were inferred solely from evidence of computed tomography (CT). CT-scan images and Hounsfield unit (HU) profiles of two continuous cores in Ottawa, Canada, provided the data to identify five lithologically distinct, mud-dominated stratal units. Distinctively, all strata exhibit a repeating pattern of HU values. The upward increase and then decrease in HU values within each bed suggests upward increasing and then decreasing silt content, which collectively, is interpreted to reflect the consistent waxing followed by waning flow conditions during a single cycle of glaciogenic meltwater discharge. Mud rhythmites at the base of the succession (Unit 1) and beds of well-stratified mud at the top (Unit 4a) exhibit well-developed parallel-stratification in the lower part of each bed; they are characterized by a range of ~250–350 HU. This wide range in HU values reflects the effective partitioning of silt-rich and clay-rich parts in each bed, and therefore bed-surface and near-bed transport processes that sorted sediment mostly by grain size, followed by low-energy sediment fallout. The silt-rich part of each bed was deposited by glaciogenic meltwater-sourced hyperpycnal flows, which due to the freshwater composition of the basin, or at least in the upper part of the water column, were able to plunge to the basin floor and sort particles along the bed. In comparison, beds of bioturbated mud (Unit 2), banded mud (Unit 3), and diffusely stratified or structureless mud (Unit 4a) have a narrower range of ~50–120 HU, indicative of poorer particle sorting. These conditions, most clearly illustrated by the bioturbation, indicate a change to a seawater basin that caused meltwater inflows to instead form buoyant, sediment-laden hypopycnal flows, which aided by clay-silt particle flocculation and/or settling-driven convection, resulted in sediment deposition directly from suspension. In addition to characteristic sedimentary structures and textures, beds within each unit also exhibit similar thickness, which often doubles or triples in the abrupt transition from one unit to the next. These changes most probably reflect abrupt and systemic changes in deglacial dynamics and its control on sediment supply that often coincide with equally abrupt changes in salinity in the Champlain Sea basin. • Cores of late Quaternary strata are scanned by computed tomography (CT). • Stratigraphic units are identified with CT-scan images and Hounsfield unit profiles. • All beds record the rhythmic waxing and then waning of glacial meltwater discharge. • Beds show abrupt changes in sedimentological character across unit boundaries. • Succession records sudden changes in sediment transport and basin fluid salinity. [ABSTRACT FROM AUTHOR]

Abstract: Robust interpretations of meltwater systems operating during ice sheet decay are integral to reconstructing deglacial patterns and style. Yet over reliance on meltwater landform morphology with limited attention to morpho-sedimentary relationships, and basin-scale geomorphic and stratigraphic context can lead to unreliable geomorphic inversion-based paleo-ice sheet reconstructions. This problem is illustrated by the evolution of Young Lake esker-like ridge (YLER) formed in the Young Lake basin (YLB) on BC's southern Fraser Plateau during decay of the last Cordilleran Ice Sheet (CIS). We integrate data from digital elevation models, aerial photographs, sedimentary outcrops, water wells and shallow geophysics (ground-penetrating radar, electrical resistivity tomography). Previous interpretations of YLER as both an esker and an ice-contact, poorly-sorted, stratified deposit emplaced by westerly flowing meltwater, imply an eastward retreating ice margin. Geophysical data from a flat-topped component of YLER reveal slipface and planar-bedded sand and gravel overlying lacustrine sediments, characteristic of a Hjulstrom delta. Eastward-dipping foresets in a Gilbert delta exist at the eastern terminus. Contextually our observations suggest, despite esker-like morphology, YLER was not deposited within a subglacial ice tunnel. Instead, it formed through deposition of subaerial outwash between and/or on dead ice in front of a regionally backwasting ice margin. The complex deglacial evolution of YLB, including a drainage reversal and formation of two glacial lakes, supports northwestward backwasting of the CIS and dead ice within YLB. We conclude that accurate geomorphic inversion of meltwater landforms for deglacial paleo-ice sheet reconstruction requires knowledge of landform-scale morpho-sedimentary relationships and basin-scale geomorphic and stratigraphic context. [Copyright &y& Elsevier]

Abstract: In the past few decades the impacts of climate warming have been significant in alpine glaciated regions. Many valley glaciers formerly linked as distributary glaciers to high-level icecaps have decoupled at their icefalls, exposing major escarpments and generating a suite of dynamic landforms dominated by mass wasting. Ice-dominated landforms, here termed icy debris fans, develop rapidly by ice avalanching, rockfall, and icy debris flow. Field-based reconnaissance studies at two alpine settings, the Wrangell Mountains of Alaska and the Southern Alps of New Zealand, provide a preliminary morphogenetic model of spatial and temporal evolution of icy debris fans in a range of alpine settings. The influence of these processes on landform evolution is largely unrecognized in the literature dealing with post-glacial landform adjustment known as the paraglacial. A better understanding of these dynamic processes will be increasingly important because of the extreme geohazards characterizing these areas. Our field studies show that after glacier decoupling, icy debris fans begin to form along the base of bedrock escarpments at the mouths of catchments and prograde over valley glaciers. The presence of a distinct catchment, apex, and fan morphology distinguishes these landforms from other landforms common in periglacial hillslope settings receiving abundant clastic debris and ice. Ice avalanching is the most abundant process involved in icy debris fan formation. Fans developed below weakly incised catchments are dominated by ice avalanching and are composed primarily of ice with minor lithic detritus. Typically, avalanches fall into the fan catchments where sediments transform into grainflows that flow onto the fans. Once on the fans, avalanche deposits ablate rapidly, flattening and concentrating lithic fragments at the surface. Icy debris fans may become thick enough to become glaciers with splay crevasse systems. Fans developed below larger, more complex catchments are composed of higher proportions of lithic detritus resulting from temporary storage of ice and lithic detritus deposits within the catchment. Episodic outbursts of meltwater from the icecap may mix with the stored sediments and mobilize icy debris flows (mixture of ice and lithic clasts) onto the fans. Our observations indicate that the entire evolutionary cycle of icy debris fans probably occurs during an early paraglacial interval (i.e., decades to 100years). Observations comparing avalanche frequency, volume, and fan morphologic evolution at the Alaska site between 2006 and 2010 illustrate complex response between icy debris fans even within the same cirque — where one fan may be growing while others are downwasting because of differences in ice supply controlled by their respective catchments and icecap contributions. As ice supply from the icecap diminishes through time, icy debris fans rapidly downwaste and eventually evolve into talus cones that receive occasional but ephemeral ice avalanches. [Copyright &y& Elsevier]

Abstract: The processes of subglacial erosion depend not only on the sliding motion of glaciers over bedrock but also on the presence of meltwater and sediment in the subglacial environment. In particular, theoretical models for subglacial quarrying and abrasion, as well as hypothesized erosion thresholds associated with subglacial sediment transport, include both positive and negative effects of subglacial water and sediment on the rate of erosion. In order to incorporate the existing theoretical models for subglacial erosion by quarrying and abrasion in a long-term glacial landscape evolution model, we here present a coupled computational framework for simulating the simultaneous flow processes of ice, water, and sediment. We supplement a higher order ice sheet model with simple long-term models for glacial hydrology and subglacial sediment transport, as well as fluvial and hillslope-related erosion processes. An important strength of the modeling framework presented relates to the morphological detail of the landscapes produced, which facilitates direct comparison with existing landforms. This improves the connection between glacial landscape evolution models, geomorphological observations, and the existing knowledge of the physical processes that operate under glaciers. We demonstrate with model examples, how increased basal meltwater pressure and transport-limited subglacial erosion lead to both positive and negative feedbacks related to glacial erosion and the formation of overdeepenings. [Copyright &y& Elsevier]

Abstract: Alpine glacial landforms (such as U-shaped troughs, hanging valleys, and cirques) have been linked to the meltwater-modulated sliding motion of glaciers. Several of these alpine landforms are associated with characteristic length scales for width and spacing, indicating that the viscosity of ice exerts a first-order control on the processes responsible for their formation. Here we present the results of three-dimensional computational experiments focusing on the influence of higher order ice dynamical effects, such as horizontal stress gradients, on long-term glacial landscape evolution. Some of the experiments presented have highly simplified bed conditions; other experiments use topography from an existing mountain range as basis for simulating glacial erosion. The experiments demonstrate how gradients in horizontal stress play a primary role in scaling the bed shear stress of glaciers. We also demonstrate how higher order ice dynamics may influence the feedback between glacial sliding and erosion, hereby providing important stabilization mechanisms that prevent runaway effects associated with the steepening of longitudinal profiles and the formation of overdeepenings. [Copyright &y& Elsevier]

Abstract: This paper explores the mechanisms by which inner gorges in the Alps were formed. It focuses on the ca. 1.5-km-long, 80-m-deep, and a few hundred meter wide Lammschlucht located in the northern foothills of the central Alps. We reconstructed the glacial cover using lateral moraines and hanging talus cones that record the elevation of the ice surface at the deglaciation stage of the LGM (Last Glacial Maximum). We used the reconstructed ice thickness patterns to calculate the erosional potential of the subglacial meltwater. The applied model is based on the principle of energy conservation and yields the pattern of downstream changes of the dynamic pressure, which is considered a measure for erosion potential. The model results suggest a maximum of the dynamic pressure at the end of the inner gorge. We interpret, therefore, that the subglacial meltwater scoured the reach toward the end of the Lammschlucht because of the enhanced dynamic pressure, which was ultimately controlled by the ice overburden. Post-glacial fluvial erosion then resulted in a readjustment through a regressive shift of the erosional front along the inner gorge farther upstream. The current location of this front lies almost in the middle of the Lammschlucht inner gorge where a step-pool channel changes into a straight plane-bed channel flowing on a deeply scoured bedrock. [Copyright &y& Elsevier]

Abstract: The Fair Oaks Dunes (FOD) of NW Indiana, USA is a large (~4500km2) inland dune field associated with the late Wisconsin deglaciation of the Laurentide Ice Sheet. Meltwaters released by the Michigan, Saginaw, and Huron–Erie lobes transported fluvioglacial sediment through the Kankakee and Tippecanoe Valleys and their tributaries. The texture and composition of the sand in the FOD suggest a Saginaw Lobe origin of sediment with some Huron–Erie Lobe sediment. Sub-mature sand with sub-angular grains and a large feldspar content suggests relatively short distance of transport during two or possibly three dune-building and dune reworking events. We propose a model which explains the development of the dunes in three stages. Dune development began during the Bølling–Allerød (stage 1, ~15–13ka) interval. During this stage anticyclonic easterly and north-easterly winds deflated the sand from outwash deposits and built transverse and barchanoid dunes on the western sides of the Tippecanoe Valley and paleo-channels. Further downwind, on the western and southwestern windward margins of the FOD, loess was deposited. During the early Younger Dryas (stage 2, ~12.5ka) atmospheric circulation changed, and westerly winds reworked the original dunes to create a great variety of parabolic dunes. Simple, hemicyclic and lobate parabolic dunes developed in the western FOD, while further downwind, in the eastern and the southern FOD, more elongated hairpin and windrift dunes developed. On the upwind side of the dune field, loess deposits remained stable and were not remobilized during the second stage dune development. By the early Holocene the FOD dunes were stabilized until their minor remobilization during the Middle Holocene (stage 3). Minor disturbances caused by anthropogenic activities have occurred in last two centuries. [ABSTRACT FROM AUTHOR]

Abstract: The Bäke creek valley is part of the young morainic area in Berlin. Its origin is related to meltwater flow and dead-ice persistence resulting in a valley with a lake–creek system. During the Late Glacial, the slopes of the valley were affected by solifluction. A Holocene brown soil developed in this material, whereas parts of the lakes were filled with limnic–telmatic sediments. The excavation site at Goerzallee revealed Bronze Age and Iron Age burial places at the upper part of the slope, as well as a fireplace further downslope, but the slope itself remained stable. Only German settlements in the 12th and 13th centuries changed the processes in the creek–lake system: the construction of water mills created a retention system with higher ground water levels in the surrounding areas. On the other hand, deforestation on the till plain and on the slope triggered erosion. Therefore, in medieval time interfingering organic sediments and sand layers were deposited in the lower part of the slope on top of the Holocene soil. The new soil which formed on top of these sediments was transformed by ploughing until the 19th century. In 1905/06 the lower part of the slope was reshaped by the construction of the Teltow Canal, following the valley of the former Bäke creek. Finally, the whole area was levelled by infill after World War II. [ABSTRACT FROM AUTHOR]

Abstract: In this study results from traditional field mapping were merged with precise elevation information from airborne LiDAR (Light detection and ranging) surveys. Morphological and sedimentological data provide new results from the Austrian (eastern) part of the Salzach piedmont glacier during times of and shortly after the Last Glacial Maximum (LGM). The variations in meltwater discharge had a major impact on the development of glacial landforms. In areas with high meltwater supply erosional or debris reworking processes play a major role, represented by drainage channels, drumlins and kettled, low relief hummocky moraine with low slope angles. Low discharge areas are associated with distinct depositional forms such as high relief end moraines (up to 30m) and hummocky moraine (averaging 20m) with high slope angles. Isolated conical kames may reach heights up to 45m. Fluvial activity is supposed to rise towards the end of the glacial cycle causing high melting rates and comprehensive debris reworking. The formation of terminal lakes and associated widespread, inorganic lake clays are the last deposits within the study area before the Salzach Glacier completely receded to its main valley. The survey of glacial landforms through the combination of field mapping and high-resolution DEM derived from airborne LiDAR missions gives precise information on transport and deposition during the last glacial cycle of the eastern Salzach Glacier piedmont lobe. [ABSTRACT FROM AUTHOR]

Abstract: Proglacial meltwater streams draining out of the Himalayan glaciers carry considerable amounts of suspended sediment, with a variety of particle sizes, because of the supraglacial, englacial, and subglacial debris, as well as formation of sediments from erosion by the movement of the ice. This paper examines particle size transported in the proglacial meltwater stream of Gangotri Glacier for seven consecutive melt seasons (May–October, 2000–2006) in order to provide information on (i) temporal variations in the particle size distribution, (ii) texture and mineralogy of the sediments, and (iii) origin and evacuation pattern of the sediments. Our results indicate dominance of silt size (0.002–0.06mm) particles (71%) followed by sand size (0.06–0.6mm) particles (24%) and clay size (<0.002mm) particles (5%) during the melt season, with increased variation as melt season progresses. The sediment contains quartz, feldspar, mica, illite, and kaolinite minerals, which represent a poor to poorly sorted fraction with a coarse to fine skewed textural distribution. Overall, this study indicates a subglacial evacuation pattern of the suspended sediment based on (i) size classification, (ii) higher percentage of coarser particles toward the end of the melting season, (iii) symmetrical to positively skewed with a kurtosis of mesokurtic to platykurtic texture, and (iv) a less-rounded shape of particle size. Our result on the evolution of meltwater pathways indicates a progressively better interconnected drainage system with advancing melt season. The evolution of meltwater pathways also demonstrates complex behavior of the glacial system and the need for a better understanding of sediment availability and contribution. [ABSTRACT FROM AUTHOR]

Abstract: The glacial landscape of the Dobrzyń Plateau in central Poland contains a complex suite of enigmatic bedforms consisting of elongate and sinuous sediment ridges occurring within an anabranched network of tunnel channels terminating at a former ice margin marked by extensive glaciofluvial fans. The term “glacial curvilineations” is proposed to describe these enigmatic bedforms that occur as fields of parallel, sinuous ridges separated by troughs. The regional pattern of glacial curvilineations replicates the morphology and pattern of tunnel channel margins and suggests a common genesis. Tunnel channels and glacial curvilineations are eroded in the interbedded diamictons and glaciofluvial sediments of the plateau. We propose that tunnel channels and glacial curvilineations are the products of subglacial meltwater erosion. Curvilineations are erosional remnants produced by longitudinal vortices within the tunnel channel-forming flows. Parallelism of curvilineations reflects spacing of turbulent structures within the subglacial flow. Tunnel channel margins also control the sinuosity of curvilineations by dictating both the path and curvature of longitudinal vortices. Arguments for meltwater erosion are strengthened by the presence of extensive glaciofluvial fans at tunnel channel termini: they are the depositional counterparts to the extensive subglacial fluvial dissection of the plateau. Understanding curvilineation genesis may shed light on glacier hydrologic processes. Tunnel channels develop abruptly in the plateau surface suggesting localized point sources of meltwater, such as drainage of subglacial and/or supraglacial lakes. The extent of tunnel channels and lateral continuity of glacial curvilineations suggests broad sheet-like flows as wide as a few kilometres. [Copyright &y& Elsevier]

Abstract: Intensive sedimentological analysis of tills, parallel-sided flutings, and a conduit fill (till esker) on the recently deglaciated foreland of Sandfellsjökull (a temperate, actively receding piedmont lobe draining the eastern margin of the Mýrdalsjökull ice cap in southern Iceland) reveals that subglacial sediment was emplaced predominantly as a dilatant A horizon after an initial phase of glacitectonite production from local outwash. Clast macrofabric strengths weakened through time, presumably in response to increasingly wetter substrate conditions, until the emplacement of the fluted till when clast alignment was more tightly constrained. The fluting phase was initiated only after boulders were plucked from an adjacent bedrock cliff and lodged at the ice–till interface. This suggests that the parallel-sided flutings constrained shearing at the ice–bed interface in a similar fashion to a fault gouge, thereby strengthening clast alignments but allowing the till to mould around larger obstacles to produce herringbone fabric patterns. Strong clast macrofabric strengths in the till esker are not parallel to the ice flow direction, but instead align parallel with the local axis of the meandering ridge. This suggests that the till esker was likely produced by the squeezing of a dilatant till into an elongated cavity or R-channel after meltwater evacuation, followed by localized deformation, constrained by the channel walls, as the channel moved downvalley because of ice flow. The short period over which the deformation took place was enough to impart weaker fabrics in parts of the conduit that lie transverse to the ice flow direction and stronger fabrics where the conduit trends toward parallelism with the ice flow. [Copyright &y& Elsevier]

Abstract: Sea-level change during the last 18,000 years is a combination of eustatic, isostatic and tectonic contributions. In an effort to minimize the tectonic contributions, our study of sea-level changes in the Aegean Sea within historical times is focused on the aseismic Attico–Cycladic geotectonic zone. On the basis of archaeological information and radiocarbon dating of coastal sedimentological formations, a sea-level curve for the Attico–Cycladic massif has been constructed for the past 5000 years and compared with existing curves. According to this curve, the rapid increase of sea level concluded prior to 5.5 ka and was followed by a slow steady rise at a rate of 0.9 mm/a up to its present stage. The latter is attributed primarily to the process of thermal expansion and secondarily to the residual melting of the glaciers and existing ice-caps. By extrapolation of the curve, the sea level at the end of the 20th century is predicted to be about 9 cm higher than the present level; this value is much lower than the prediction of the last IPCC report (49 cm). If higher SLR rates are realised in the next few decades, then the excess 40 cm of the IPCC prediction can be attributed to human-induced global climatic change. [Copyright &y& Elsevier]

Glacial curvilineations (GCLs) are enigmatic landforms recently discovered in the southern peripheral area of the last Scandinavian Ice Sheet (SIS). They consist of multiple parallel, winding ridges several metres high and up to several kilometers long, systematically arranged in groups of common geomorphic appearance. GCLs create spectacular landscapes whose origin generates much controversy. Expanding from the first GCLs finding in central Poland, we now present an inventory of other GCLs occurrences along the SIS margin in Poland, Germany and Denmark based on analysis of high-resolution LiDAR digital elevation models. We document a total of 59 glacial curvilineation fields and focus on the geomophic characteristics of the 43 most conspicuous ones. Each of these fields consists of smaller units called GCL swarms, 137 in total. The fields differ strongly in areal coverage (between 1 and 358 km2), number of swarms (between 1 and 21) and number of individual landforms (between 2 and 255). All GCL fields occur in tunnel valleys terminating at the ice margin, typically at various topographical levels. Our findings, interpreted in the context of glacial geological processes, support the origin of GCLs as erosional remnants of antecedent landscapes carved by channelized subglacial meltwater flows. • 59 fields of glacial curvilineations (GCLs) are detected in the European Lowland. • GCLs occur in tunnel valleys and have highly diversified morphologies. • GCLs are remnants of antecedent landscapes carved by subglacial meltwater flows. • GCLs stress the role of subglacial meltwater erosion in shaping glacial landscapes. [ABSTRACT FROM AUTHOR]