Search

Glaciers are one of the most active erosional forces sculpting mountainous regions, and understanding the diversity of glacial valleys is a key to advancing knowledge of mountain evolution. 'Inverted trapezoidal' glacial valleys are an important type of glacial erosional landform, and research on their morphologic characteristics and causal mechanisms might contribute to a deeper comprehension of the variety of landforms formed by glacial erosion. In this paper, ALOS 12.5m DEM data and field geomorphologic surveys were used to quantitatively extract 171 transect parameters from 32 valleys in the study area and to quantitatively describe the morphologic characteristics of the inverted trapezoidal glacial valley transects based on the V-index model. The results show that the minimum V-index value for glacial valley cross-sections in the study area is 0.42, the maximum value is 0.86, and the mean value is 0.60. The most important factors influencing the diversity in the morphology of glacial valleys in the study area are the area of glacial action and climatic conditions. The formation of inverted trapezoidal glacial valleys may be attributed to the stable glacial action region of ice caps with gentle topography in Geladandong snow mountain. Research highlights: The minimum value of the V-index for glacial valley cross-sections in the study area was 0.42, the maximum value was 0.86, and the mean value was 0.60. The greatest number of cross-sections were concentrated in the 0.60 ~0.70 interval. The most important factor influencing the diversity in the morphology of glacial valleys in the study area are the area of glacial action and climatic conditions. The formation of inverted trapezoidal glacial valleys may be attributed to the stable glacial action region of ice caps with gentle topography in Geladandong snow mountain. [ABSTRACT FROM AUTHOR]

Amongst the most neglected landforms in formerly glaciated mountain environments are the scars of major rock-slope failures where the displaced rock or runout debris has been removed by glacial erosion. The characteristics of 33 such debris-free failure scars (DFFSs) on Torridonian sandstone terrain were analysed. These range from 0.011 to 0.183 km2 in ground area, and scar volume implies removal of ~ 0.4–9.9 Mt of rock. Failure planes are planar or stepped at gradients of 37–50°, implying failure as 'rough' translational slides; most probably represent former rock avalanches or fragmented rockslides where shear through bedding planes resulted in runout fragmentation. Extension of 85 % to the slope crest is consistent with coseismic triggering during periods of glacio-isostatic crustal uplift. At least ten DFFSs demonstrably pre-date expansion of the last ice sheet at ~ 35 ka, and at least five probably represent failure that occurred in the Lateglacial interval of ~ 16–11.7 ka. Fourteen are located within cirques, confirming the importance of RSFs in cirque extension during ice-free interglacials or interstades; others have contributed to trough widening and the formation of arêtes. Older upper-slope cavities in Torridonian mountains are probably also the results of (possibly recurrent) rock-slope failures. It is concluded that the large-scale morphology of the Torridonian sandstone mountains reflects a long-term synergic relationship between alternating episodes of glacial erosion and rock-slope failure: reduction of rock-slope stability during each glacial-deglacial cycle has predisposed slopes to eventual failure, with subsequent glacial removal of displaced blocks and runout debris. [ABSTRACT FROM AUTHOR]

The onset of glaciation in the late Cenozoic caused rapid bedrock erosion above the snowline; however, whether the influx of eroded sediment is recorded in continental weathering and basin accumulation rates is an ongoing debate. We propose that the transport of glacially eroded bedrock through the fluvial system damps the signal of rapid headwater erosion and results in steady basin‐integrated sediment flux. Using a numerical model with integrated glacial and fluvial erosion, we find that headwater bedrock erosion rates increase rapidly at the onset of glaciation and continue to fluctuate with climatic oscillation. However, bedrock erosion rates decrease in the downstream fluvial system because larger grain sizes from glaciers result in an increase in sediment cover effect. When erosion and sediment flux rates are averaged, long‐term sediment flux is similar to nonglacial flux values, while localized bedrock erosion rates in the glaciated landscape are elevated 2–4 times compared to nonglacial values. Our simulated values are consistent with field measurements of headwater bedrock erosion, and the pattern of sediment flux and fluvial erosion matches paraglacial theory and terrace aggradation records. Thus, we emphasize that the bedload produced from glacial erosion provides a missing link to reconcile late Cenozoic erosion records. Plain Language Summary: Glaciers are effective erosion agents and the start of mountain glaciation is thought to correspond to higher alpine erosion rates. However, at the landscape‐scale, there is little to no change in erosion rates across the start of glaciation. In order to connect across these scales, we use a computer model to calculate erosion rates and sediment transfer rates. We find that the increase in sediment size from glaciation will lower erosion rates in rivers. Larger sediment sits on the riverbed and protects the underlying rock from erosion. Despite rapid erosion by glaciers upstream of the river, the slower erosion rates in the river result in a constant rate of sediment transferred out. Therefore, sediment transfer from glacier to river systems is an important process for understanding erosion across landscape scales. Key Points: Bedrock erosion downstream of glaciers is damped through an increase in sediment cover effect caused by glacier‐produced sedimentBasin‐wide sediment flux is similar to unglaciated sediment flux at timescales of >100 kyGlacially derived bedload provides a missing link between rapid bedrock erosion rates and steady basin accumulation and weathering rates [ABSTRACT FROM AUTHOR]

We present observations and maps of Mars' northern polar spiral trough migration paths (TMPs) as revealed through the 3D SHARAD (Shallow Radar) data volume, identify patterns of TMP morphology, and provide interpretations and implications of these TMPs on past climate. This data set provides additional spatial context over traditional 2D data as it allows for radargrams to be taken perpendicular to each trough strike, which minimizes distortion of migration paths due to oblique viewing geometry. Here, we present an expanded survey of trough migration and analysis of surface troughs across the north polar layered deposits. We corroborate many previous observations of trough migration such as: the general poleward and stratigraphically upward migration from the TMP initiation point; the broadly similar depth of trough initiation across the cap; regional variability in TMP morphology; and the presence of buried promontories. Our results support the presence of two generations of troughs, though we cannot confirm that the oldest generation originated deeper than ∼600 m beneath the current surface, as previously reported. Two generations of troughs suggest that climate conditions favorable for initiation of trough migration have occurred at least twice. Trough initiation occurring only in the upper ∼600 m suggests that troughs are relatively recent features in the polar cap, developing after the formation of ∼half the current cap height. The mapped TMPs provide insight into the consistency of Mars' climate during the accumulation of the past few hundred meters of ice by recording the boundary of erosion and accumulation of ice at the troughs. Plain Language Summary: Mars' northern polar water ice cap has troughs cutting into the surface in a spiral pattern clockwise out from the north pole. These polar spiral troughs are believed to migrate toward the pole through time through the transport of ice from the high‐side to the low‐side. Trough migration paths, which trace previous locations of the troughs, are features that occur in the subsurface of Mars' northern polar cap and are revealed by ground‐penetrating radar. Using a 3D data set of the radar observations, we are better able to map these features than past efforts with 2D data sets. We present an expanded survey of trough migration and explore patterns in the surface troughs across the north polar cap. We corroborate previous studies that trough migration paths start at two different depths in the ice cap, though we map the oldest generation to only depths of ∼600 m (shallower than previously presented). We observe patterns in the shapes of migration paths, suggesting that local processes such as winds may affect the shapes. Troughs near the edge of the polar cap have migrated more poleward than vertically from ice accumulation, which causes the migration paths to appear flat. These observations provide information about Mars' past climate. Key Points: Troughs are constructional features that migrate, typically poleward and stratigraphically upward, as Mars' climate variesWe map trough migration paths across the north polar cap and analyze surface trough morphology and patterns using the 3D SHARAD dataTrough migration paths act as records of volatile mass balance, revealing regional and temporal patterns of accumulation and retreat [ABSTRACT FROM AUTHOR]

Climate contrasts across drainage divides, such as orographic precipitation, are ubiquitous in mountain ranges, and as a result, mountain topography is often asymmetric. During glacial periods, these climate gradients can generate asymmetric glaciation, which may modify topographic asymmetry and drive divide migration during glacial‐interglacial cycles. Here we quantify topographic asymmetry caused by asymmetric glaciation and its sensitivity to different climate scenarios. Using an analytical model of a steady‐state glacial profile, we find that the degree of topographic asymmetry is primarily controlled by differences in the equilibrium line altitude across the divide. Our results show that glacial erosion can respond to the same climate asymmetry differently than fluvial erosion. When there are precipitation differences across the divide, glacial erosion produces greater topographic asymmetry than fluvial erosion, all else equal. These findings suggest that glaciations may promote drainage reorganization and landscape transience in intermittently glaciated mountain ranges. Plain Language Summary: In mountainous regions, the amount of rain, snow, and ice that falls and builds up often varies from one side of a mountain to the other. Over thousands to millions of years, these variations can make the length and steepness of the mountain sides differ, too. When glaciers form during ice ages, they can make this asymmetry in the topography even more pronounced. Our study looks at how glaciers affect the landscape and how glaciers and landscapes change in different climate conditions. Using a computer model, we discovered that the landscape becomes even more asymmetric when it is shaped by glaciers compared to when it is shaped by rivers. Our findings suggest that glaciers can cause landscapes to constantly change between ice ages. Key Points: We quantify topographic asymmetry caused by asymmetric glaciationGlacial erosion causes greater topographic asymmetry than fluvial erosion all else equalGlacial‐interglacial cycles can cause divide migration [ABSTRACT FROM AUTHOR]

Understanding the rates and mechanisms of erosion by subglacial quarrying is a major unsolved problem in geomorphology. Stress enhancement due to load concentration on bedrock ledges between cavities is hypothesized to drive the growth of fractures. Prior work assumed the formation of vertically oriented tensile fractures at the downstream margins of cavities as the controlling process, but did not account for the evolution of the stress field as fractures lengthen, and in particular the dominance of the shearing mode at fracture tips. We used 2D finite element analysis and J‐integral methods to analyze stress intensity factors and fracture growth potentials at the tips of preexisting fractures in loaded bedrock steps, taking into account normal and shear components and measured rock strengths. By examining different step heights, step riser angles, rock types, prior fracture locations and orientations, and extents of ice‐rock contact zones, we identified some situations favorable for fracture growth, especially in brittle rock types. Typically, however, the growth direction will not be vertically downward but angled up‐glacier away from the step riser, a situation unfavorable for quarrying. Moreover, in many situations, the normal stress across fracture planes will be compressive. Non‐vertical step risers buttress the bedrock and also suppress fracture growth. In contrast, reducing the sizes of ice‐rock contact zones not only increases the loading magnitude, as previously recognized, but also increases intensification of tensile stress at the tips of fractures located just up‐glacier. Thus, larger cavities, and hence, fast sliding and low effective pressures, favor quarrying more strongly than previously recognized. Plain Language Summary: Glaciers carve into landscapes, in particular helping to define the terrain of high mountain ranges and high‐latitude continents. A major way glaciers achieve this is subglacial quarrying; by sliding over their substrates, glaciers unevenly concentrate their weight on bedrock bumps and ledges, causing existing bedrock cracks to grow, ultimately dislodging chunks of rock which further scrape along downstream to cause further erosion. Scientists do not yet understand how enough fracturing occurs for quarrying to happen, or how rapidly. We used software to mathematically evaluate the extent to which the uneven pressures cause bedrock flaws to pull apart or slide apart in different situations under glaciers. Factors enhancing erosion include taller bedrock steps, vertical step faces, cracks and pressures positioned closer to step edges, and rock types susceptible to shattering. Our analysis corrected some problems in previous research but also failed to identify how rock fracturing under glaciers could be extensive enough to fully dislodge rocks, an issue we continue to investigate. Key Points: Uneven distribution of a glacier's weight on stepped bedrock generates stresses large enough to grow existing fractures in some situationsHow crack growth separates blocks to allow quarrying remains unsolved; prior work does not distinguish between tensile and shear failureGrowth is favored by greater step height, vertical risers, and smaller loading zones, the latter effect being stronger than earlier thought [ABSTRACT FROM AUTHOR]

High‐relief glacial valleys shape the modern topography of the Southern Patagonian Andes, but their formation remains poorly understood. Two Miocene plutonic complexes in the Andean retroarc, the Fitz Roy (49°S) and Torres del Paine (51°S) massifs, were emplaced between 16.9–16.4 Ma and 12.6–12.4 Ma, respectively. Subduction of oceanic ridge segments initiated ca. 16 Ma at 54°S, leading to northward opening of a slab window with associated mantle upwelling. The onset of major glaciations caused drastic topographic changes since ca. 7 Ma. To constrain the respective contributions of tectonic‐mantle dynamics and fluvio‐glacial erosion to rock exhumation and landscape evolution, we perform inverse thermal modeling of a new data set of zircon and apatite (U‐Th)/He from the two massifs, complemented by apatite 4He/3He data for Torres del Paine. Our results show rapid rock exhumation recorded only in the Fitz Roy massif between 10 and 8 Ma, which we ascribe to local mantle upwelling forcing surface uplift and intensified erosion around 49°S. Both massifs record a pulse of rock exhumation between 7 and 4 Ma, which we interpret as enhanced erosion during the beginning of Patagonian glaciations. After a period of erosional and tectonic quiescence in the Pliocene, increased rock exhumation since 3–2 Ma is interpreted as the result of alpine glacial valley carving promoted by reinforced glacial‐interglacial cycles. This study highlights that glacial erosion was the main driver to rock exhumation in the Patagonian retroarc since 7 Ma, but that mantle upwelling might be a driving force to rock exhumation as well. Plain Language Summary: The isotopic system (U‐Th)/He in apatite and zircon record the ages in which a rock experiences relatively low temperatures (200–60°C) at shallow crustal depths (6–1 km). We present a new data set of low‐temperature thermochronometers for rocks of the Fitz Roy and Torres del Paine mountains in the Southern Patagonian Andes. Fast rock cooling can be forced by intensified surface erosion, and/or tectonic and mantle activity. An episode of fast cooling between 10 and 8 Ma was identified in the Fitz Roy mountains, and mantle upwelling forcing surface uplift, combined with high fluvial erosion may have caused fast rock exhumation. A regional episode of fast rock cooling between 7 and 4 Ma causing 1–3 km of exhumation in the Fitz Roy and Torres del Paine is coincident with the onset of Patagonian glaciations, which would have enhanced erosion and, thus, rock exhumation. An episode of fast rock cooling in the Quaternary is recorded in Torres del Paine rocks, interpreted as enhanced fluvio‐glacial erosion during the Plio‐Pleistocene climate transition toward faster glacial/interglacial cycles. Therefore, we were able to quantify separately the effects of tectonics and climate changes on rock exhumation, what is usually difficult due to simultaneously occurring processes. Key Points: Mantle upwelling in Southern Patagonia is the most likely mechanism forcing rock exhumation between 10 and 8 Ma in the Fitz Roy massifApatite (U‐Th)/He data reveal glacial erosion as the main driver to the exhumation of the Fitz Roy and Torres del Paine between 7 and 4 MaApatite 4He/3He data reveal intensified fluvio‐glacial erosion in Torres del Paine as a result of the Plio‐Pleistocene climate transition [ABSTRACT FROM AUTHOR]

The deposition of the Witwatersrand Supergroup commenced with a major marine transgression across the granite/greenstone terrain of the Kaapvaal Craton, depositing the predominantly marine West Rand Group. Possibly as a consequence of continental convergence the craton became subject to regional transpression, which began to fragment the widely distributed West Rand Group into a number of separate sub-basins, flanked by uplifts. The sedimentation style changed from shallow marine to fluvial, initiating the deposition of the Central Rand Group. The sub-basins in which sedimentation took place were separated by faults, anticlines or monoclines. In the Far East Rand these sub-basins included the Evander, Delmas, South Rand and East Rand Basins. Complete separation of these sub-basins only occurred after deposition of the Kimberley Reef. Left lateral transpression caused syn-depositional periclinal folding of Witwatersrand strata trending northwestsoutheast. Important structures that developed at this stage include the Springs Monocline, which formed a ledge separating the East Rand from the main Witwatersrand Basin, and the Fold-Fault, which formed a ridge dividing the Evander Basin into two. Contrary to previous interpretations, the Fold-Fault is not a basin margin structure because the Evander Basin continues to its northeast, and hence it is an intra-basinal fold. During the early phases of Central Rand Group deposition in the East Rand Basin, sediments were derived from greenstone poor granitic source rocks in the north and northwest. In contrast, in the adjoining Evander area, pre-Kimberley sediment was derived from greenstone-dominated terrain to the northeast. Underground mapping of the immediate footwall strata of the Kimberley Reef at Evander has provided unambiguous evidence for glacial activity at that time. It is unclear whether glaciation was involved in the formation of the Kimberley Reef itself. However, glacial activity was responsible for the deposition of extensive glaciogenic sediments across the Far East Rand in the form of diamictites (termed puddingstones in the older literature) and associated channel deposits (MK1, eskers?). A period of erosion followed this glacial episode and gave rise to an extensive gravel lag across the erosion surface, which constitutes the Kimberley Reef at Evander. The erosion surface on which the reef lies is thus a large pediment. The palaeocurrents responsible for this degradation flowed from the west and southwest and thus indicate a reversal of the local palaeoslope relative to pre-Kimberley Reef times. Palaeocurrent measurements in the Kimberley Reef and its hangingwall are consistent in their azimuths suggesting that flow was dispersed across the pediment rather than originating from a local point source. The sources of gold which became concentrated in the gravel lag appear to have been predominantly the LK1 and MK2 conglomerates and possibly gold present in the diamictites. The footwall strata had been derived from a greenstone-rich source in the east. Their greenstone signature was carried over into the Kimberley Reef, notably the presence of banded iron formation clasts and high concentrations of osmiridium and chromite. Northwest-southeast folding continued during Kimberley Reef formation. A synclinal trough bounded along its northeastern flank by an anticline, the Fold-Fault, developed across the pre-Kimberley surface. This structure created accommodation space, which caused local thickening of the Kimberley Reef package. Thickening of the reef in the Fold-Fault area is therefore not a consequence of fluvial channelisation but a result of thickening due to synsedimentary warping. Palaeocurrent directions in this trough continued in a northeasterly direction, perpendicular to the warp axis. The synclinal feature associated with the Fold-Fault remained active after the formation of the Kimberley Reef. As a consequence, isopachs of hangingwall strata also thicken towards the trough. The gold grade in the Kimberley Reef is inversely related to reef thickness: where the reef is thick, the gold grade is generally low. Most of the gold was scavenged from the footwall. The scavanged material was winnowed on the erosion surface, producing the high grades characteristic of the thin Kimberley Reef present at the southwestern and northwestern margins of the basin. In the trough which borders the western flank of the Fold-Fault, grade is lower due to an increase in quartzite partings. The Fold-Fault is a syn- to post depositional anticline and it is expected that the reef will thin onto the structure. Palaeocurrents are perpendicular to the anticline and therefore gold grades are expected to increase as the reef thins. Because of the local derivation of much of the Kimberley Reef, the proximal to distal indicators such as changes in pebble size, U/Au ratio and gold fineness are weakly developed to absent. Carbon is often associated with gold in the Witwatersrand Basin but in the case of the Evander Goldfield, carbon does not appear to have played a significant role in gold enrichment on a regional scale. However, there is anecdotal evidence of gold being associated with carbon on a local scale. We suggest that the burial of the Kimberley Reef occurred as a result of an increase in sediment supply to the depository. Distal deposits which characteristically contain a high proportion of quartzite partings (HW1 and HW2), transgressed across the palaeo-plain and buried the Kimberley pediment surface. [ABSTRACT FROM AUTHOR]

The subglacial landscape of Antarctica records and influences the behaviour of its overlying ice sheet. However, in many places, the evolution of the landscape and its control on ice sheet behaviour have not been investigated in detail. Using recently released radio-echo sounding data, we investigate the subglacial landscape of the Evans–Rutford region of West Antarctica. Following quantitative analysis of the landscape morphology under ice-loaded and ice-unloaded conditions, we identify 10 flat surfaces distributed across the region. Across these 10 surfaces, we identify two distinct populations based on clustering of elevations, which potentially represent remnants of regionally coherent pre-glacial surfaces underlying the West Antarctic Ice Sheet (WAIS). The surfaces are bounded by deeply incised glacial troughs, some of which have potential tectonic controls. We assess two hypotheses for the evolution of the regional landscape: (1) passive-margin evolution associated with the break-up of the Gondwana supercontinent or (2) an extensive planation surface that may have been uplifted in association with either the West Antarctic Rift System or cessation of subduction at the base of the Antarctic Peninsula. We suggest that passive-margin evolution is the most likely of these two mechanisms, with the erosion of glacial troughs adjacent to, and incising, the flat surfaces likely having coincided with the growth of the WAIS. These flat surfaces also demonstrate similarities to other identified surfaces, indicating that a similar formational process may have been acting more widely around the Weddell Sea embayment. The subsequent fluctuations of ice flow, basal thermal regime, and erosion patterns of the WAIS are therefore controlled by the regional tectonic structures. [ABSTRACT FROM AUTHOR]

Glacial and periglacial sediments and landforms record the chronology of glaciation and amount of Pleistocene erosion during colder periods that added substantially to global sediment budgets and contributed to the global CO2 cycle. The now-drained glacial Lake Devlin, dammed in a Front Range tributary valley by a glacier in the North Branch of Boulder Creek (Colorado, USA) preserves an important sedimentary archive of the ca. 32-14 ka Pinedale glaciation, recording both paleoclimate information and an integrated measure of glacial and periglacial erosion rates over a full glacial cycle. Despite rapid erosion of fine-grained deposits after the lake drained, most sediment generated during Pinedale time remains as legacy deposits in the catchment. Geomorphic evidence and dating of glaciolacustrine sediment from surface exposures demonstrate that the ca. 30 ka Pinedale glacial advance was nearly as extensive as the local Late Glacial Maximum at ca. 20 ka. Sedimentary archives dated by 14C, optically stimulated luminescence, and cosmogenic nuclides extend earlier studies (Madole et al., 1973) of pollen and magnetic susceptibility (MS) in cores from the glaciolacustrine deposits of Lake Devlin and of Pinedale climate. Records suggest short-term warming and biotic change at ca. 15 ka after ~14 kyr of cold, dry conditions punctuated by MS peaks at ca. 26.5 ka, 20 ka, and 16.5 ka. Lake Devlin drained catastrophically after ca. 14 ka, millennia after ice had retreated upvalley from the lateral moraine that dammed the lake. Sediment production during the Pinedale was equivalent to a periglacial and glacial erosion rate of ~70 mm kyr1, several times higher than long-term rates in the adjacent Front Range, but much lower than rates measured where modern glaciers are eroding weak bedrock in zones of rapid rock uplift, such as SSE Alaska, USA. Data from the Lake Devlin basin contribute to contemporary discussions of how glacial erosion influences the global CO2 cycle. [ABSTRACT FROM AUTHOR]

Inheritance from prior exposure often complicates the interpretation of terrestrial cosmogenic nuclide (TCN) inventories in glaciated terrain. Lochnagar, a mountain in eastern Scotland, holds a clear geomorphological record of corrie glaciation and the thinning of the last Scottish ice sheet over the last ~15 ka. Yet attempts to date the main stages in deglaciation after sampling of 21 granite boulders for 10Be, 26Al and 14C from corrie moraines, an ice sheet lateral moraine and boulder spreads revealed widespread, but variable, TCN inheritance. Only the youngest boulder ages fit within the range of expected deglaciation ages. To identify the sources of geological uncertainty, we provide simple models of ice cover duration and erosion histories for plateau, corrie and strath landscape domains, identify the variable nuclide inheritance that derives from different sources for boulders in these domains, and outline the effects of rotation, splitting and erosion of boulders during glacial transport. The combined effects increase clustering around arbitrary mean TCN values that exceed deglaciation ages. A further implication is that boulders have survived beneath overriding ice sheets. Such boulder trapping at Lochnagar may have resulted from topographic controls on katabatic winds and surface ablation acting on a thinning, cold‐based ice sheet. [ABSTRACT FROM AUTHOR]

This study investigated the thermally induced aging effects on a carbon fiber-reinforced composite (CFRP) comprising benzoxazine (BZ) and cycloaliphatic epoxy resin (CER). Herein, we employed various testing methodologies to assess the aging behavior of CFRP samples with differing CER and BZ ratios. Traditional techniques, including weight change quantification and qualitative analysis of surface morphology, reveal that higher CER content correlates with increased aging. Additionally, wettability analysis demonstrates that both BZ and BZ-CER composites exhibit heightened hydrophilicity with thermal aging, potentially exacerbating concerns such as icing and surface erosion. Notably, the BZ-CER composite displays greater hydrophilicity compared to the BZ composite, consistent with weight change trends. These findings underscore the utility of surface wettability analysis as a valuable tool for monitoring thermo-oxidative aging in polymers and their surface behavior in response to fluid interactions, particularly within high glass transition temperature ( T g ) BZ-CER systems utilized in structural composite applications. [ABSTRACT FROM AUTHOR]

The Antarctic ice sheet blankets >99% of the continent and limits our ability to study how subglacial geology and topography have evolved through time. Ice-rafted dropstones derived from the Antarctic subglacial continental interior at different times during the late Cenozoic provide valuable thermal history proxies to understand this geologic history. We applied multiple thermochronometers covering a range of closure temperatures (60-800 °C) to 10 dropstones collected during Integrated Ocean Drilling Program (IODP) Expedition 318 in order to explore the subglacial geology and thermal and exhumation history of the Wilkes Subglacial Basin. The Wilkes Subglacial Basin is a key target for study because ice-sheet models show it was an area of ice-sheet retreat that significantly contributed to sea-level rise during past warm periods. Depositional ages of dropstones range from early Oligocene to late Pleistocene and have zircon U-Pb or 40Ar/39Ar ages indicating sources from the Mertz shear zone, Adélie craton, Ferrar large igneous province, and Millen schist belt. Dropstones from the Mertz shear zone and Adélie craton experienced three cooling periods (1700-1500 Ma; 500-280 Ma; 34-0 Ma) and two periods of extremely slow cooling rates (1500-500 Ma; 280-34 Ma). Low-temperature thermochronometers from seven of the dropstones record cooling during the Paleozoic, potentially recording the Ross or Pan-African orogenies, and during the Mesozoic, potentially recording late Paleozoic to Mesozoic rifting. These dropstones then resided within ~500 m of the surface since the late Paleozoic and early Mesozoic. In contrast, two dropstones deposited during the mid-Pliocene, one from the Mertz shear zone and one from Adélie craton, show evidence for localized post-Eocene glacial erosion of =2 km. [ABSTRACT FROM AUTHOR]

To inhibit the quality deterioration caused by the frozen storage of surimi products, this work investigated the effect of freezing methods, including raw-freezing-settingheating, raw-setting-freezing-heating, and raw-setting-heating-freezing, on quality changes in surimi gel. The moisture loss, physical--chemical properties, and protein structure conformation of surimi gel derived from Bombay duck (BD) were assessed following frozen storage periods of 20, 40, and 60 days. The findings suggest that the raw-setting-heating-freezing method yielded optimal surimi gel properties with extended frozen storage time. Employing this approach led to a reduction in thawing loss, while cooking loss remained constant. After 60 days of frozen storage, the hardness exhibited an initial increase followed by a subsequent decrease, and waterholding capacity increased to 68.2%. Notably, the impact on surimi gel during the late stage of frozen storage was more pronounced throughout the formation of ice crystals, resulting in decreased disulfide bond content. Scanning hematoxylin--eosin (HE) staining slices of samples following thawing and heating demonstrated that the raw-setting-heating-freezing method could better resist the effect of ice crystals in frozen storage period on surimi tissue, while the gel on setting process could delay the erosion imposed on by ice crystals during frozen storage. This study provides a scientific foundation for the industrialization on frozen BD surimi products. [ABSTRACT FROM AUTHOR]

This study presents the results of a 2D numerical basin and petroleum systems model of the Olga Basin in the NW Barents Sea offshore northern Norway, a frontier exploration area in which there are abundant seafloor oil and gas seepages. The effects of Pleistocene ice sheet advances on rock properties and subsurface fluid migration in this area, and on seafloor hydrocarbon seepage, are not well understood. The 2D numerical model takes account of recurrent ice advances and retreats, together with related erosional and temperature effects, and investigates the influence of these parameters on fluid migration. Model results show that Pleistocene glaciations reduced the temperature in the sedimentary succession in the Olga Basin by up to 20 °C, for example in the uppermost Cretaceous and Jurassic sediments which underlie the seafloor down to a depth of 0.5 to 1 km. The decrease in temperature was in general predominantly related to the intensity of glacial erosion, which was set in this study to a depth of 600 m based on previous studies. Hydrocarbon fluids expelled from potential thermogenic source rocks of Carboniferous to Triassic ages on the SW margin of the Olga Basin migrated to the seafloor through permeable carrier beds. However, fluid migration to the surface in the NE of the study area took place along fault conduits. In a closed fault model scenario, only 0.3 Mt of hydrocarbons are modelled to have migrated along the 0.5 km wide model section; in a second scenario with partially open faults, about 22 Mt of hydrocarbons, representing about 11% of the total hydrocarbons generated by potential thermogenic source rocks in the study area, were lost to the surface during the Pleistocene. The potential for microbial methane generation in the Olga Basin was limited both during the Pleistocene and at the present day due to the significant reduction in temperature during glacial episodes, and due to the intense glacial‐related erosion of the Mesozoic to Cenozoic stratigraphy. During glacial stages, the gas hydrate stability zone beneath the ice sheet is modelled to have extended to a depth of up to 900 m for a pure methane composition, and to a depth of up to 1100 m for a possible thermogenic‐sourced mixed gas composition of 90% methane, 7% propane and 3% ethane. Gas hydrates with this mixed composition are modelled to have been stable in the Olga Basin during the last three glacial advances and into the present. These modelling results provide an insight into the key factors controlling the migration and surface leakage of hydrocarbon fluids in the Olga Basin region, and into the effects of glaciations on rock properties in a glaciated basin. [ABSTRACT FROM AUTHOR]

Abstract Climate contrasts across drainage divides, such as orographic precipitation, are ubiquitous in mountain ranges, and as a result, mountain topography is often asymmetric. During glacial periods, these climate gradients can generate asymmetric glaciation, which may modify topographic asymmetry and drive divide migration during glacial‐interglacial cycles. Here we quantify topographic asymmetry caused by asymmetric glaciation and its sensitivity to different climate scenarios. Using an analytical model of a steady‐state glacial profile, we find that the degree of topographic asymmetry is primarily controlled by differences in the equilibrium line altitude across the divide. Our results show that glacial erosion can respond to the same climate asymmetry differently than fluvial erosion. When there are precipitation differences across the divide, glacial erosion produces greater topographic asymmetry than fluvial erosion, all else equal. These findings suggest that glaciations may promote drainage reorganization and landscape transience in intermittently glaciated mountain ranges.

The modern relief of Southern Africa is characterised by stepped plateaus bordered by escarpments. This morphology is thought to result from stepwise uplift and ensuing continental-scale erosion of the region as it rode over Africa's mantle 'superplume' following the break-up of Gondwana, i.e. since the mid-Mesozoic. We demonstrate in this contribution that this modern morphology of Southern Africa is in fact largely inherited from glacial erosion associated to the Late Paleozoic Ice Age (LPIA) that occurred between 370 and 260 Myr ago, during which Gondwana – which included Southern Africa – was covered in thick ice masses. Southern Africa hosts vast (up to 106 km²) and thick (up to 5 km) sedimentary basins ranging from the Carboniferous, represented by glaciogenic sediments tied to the LPIA, to the Jurassic-Cretaceous. These basins are separated by intervening regions largely underlain by Archean to Paleoproterozoic cratonic areas that correspond to paleohighlands that preserve much of the morphology that existed when sedimentary basins formed, and particularly glacial landforms. In this contribution, we review published field and remote data and provide new large-scale interpretation of the geomorphology of these paleohighlands of Southern Africa. Our foremost finding is that over Southern Africa, vast surfaces, tens to hundreds of thousands km² (71.000–360.000 km²) are exhumed glacial landscapes tied to the LPIA. These glacial landscapes manifest in the form of cm-scale striated pavements, m-scale fields of roches moutonnées , whalebacks and crag-and-tails, narrow gorges cut into high-standing mountain ranges, and km-scale planation surfaces and large U-shaped valleys, overdeepenings, fjords and troughs up to 200 km in length. Many modern savannahs and desertic landscapes of Southern Africa are therefore relict glacial landscapes and relief ca. 300 Myr old. These exhumed glacial relief moreover exerts a strong control on the modern-day aspect of the geomorphology of Southern Africa as (1) some escarpments that delineate high-standing plateaux from valleys and coastal plains are inherited glacial relief in which glacial valleys are carved, (2) some hill or mountain ranges already existed by LPIA times and were likely modelled by glacial erosion, and (3) the drainage network of many of the main rivers of Southern Africa is funnelled through ancient glacial valleys. This remarkable preservation allowed us to reconstruct the paleogeography of Southern Africa in the aftermath of the LPIA, consisting of highlands over which ice masses nucleated and from which they flowed through the escarpments and toward lowlands that now correspond to sedimentary basins. Our findings therefore indicate that glacial landforms and relief of continental-scale can survive over tens to hundreds of million years. This preservation and modern exposure of the glacial paleolandscapes were achieved through burial under piles of Karoo sediments and lavas over ca. 120 to 170 million years and a subsequent exhumation since the middle Mesozoic owing to the uplift of Southern Africa. Owing to strong erodibility contrasts between resistant Precambrian bedrock and softer sedimentary infill, the glacial landscapes have been exhumed and rejuvenated. We therefore emphasise the need of considering the legacy of glacial erosion processes and the resulting presence of glacial landscapes when assessing the post-Gondwana-breakup evolution of Southern African topography and its resulting modern-day aspect, as well as inferences about climate changes and tectonic processes. Finally, we explore the potential pre-LPIA origin for some of the landscapes. In the Kaoko region of northern Namibia, the escarpments into which glacial valleys are carved may correspond to a reminiscence of the Kaoko Pan-African Belt, whose crustal structures were either reactivated or where relief persisted since then. In South Africa, the escarpment bordering the paleohighland corresponds to crustal-scale faults that might have been reactivated during LPIA by subsidence processes. These inherited morphological or crustal features may have been re-exploited and enhanced by glacial erosion during the LPIA, as it is the case for some Quaternary glacial morphology. [ABSTRACT FROM AUTHOR]

Beyond the impact of glacial isostatic adjustment, landscape evolution is typically neglected at large scale when considering the basal boundary condition for ice sheet and climate modelling over past glacial cycles. Erosion and changing sediment loads impact bed elevation, land/sea mask, and basal drag. To date, how the above affects past ice sheet evolution is unclear. Constraining the role that Pliocene regolith may have played in Pleistocene glacial cycle variability requires bounds on the amount of regolith preceding those glacial cycles. However, quantitative bounds on regolith thickness at the spatial scale of the glaciated regions of North America are currently absent in the literature. To address the above, we present an updated sediment production and transport model with dynamically calculated soft sediment mask, isostatic adjustment to dynamical sediment load and bedrock erosion, and a new subglacial hydrology model coupled to the Glacial Systems Model. The coupled model is capable of multi-million year integrations driven only by greenhouse gas concentration and insolation. The model passes a set of verification tests and conserves mass. We assess parametric sensitivity of sediment transport rates. We compare the final sediment solutions in an ensemble of whole-Pleistocene simulations for a range of initial (Pliocene) regolith thicknesses against multiple estimates for present day drift thickness distribution, Quaternary sediment volume in the Atlantic Ocean, and erosion depth estimates. Consistency of modelling and data constraints requires a Pliocene regolith thickness of less than 50 m. [ABSTRACT FROM AUTHOR]

A quantitative understanding of how sediment discharge from subglacial fluvial systems varies in response to glacio-hydrological conditions is essential for understanding marine systems around Greenland and Antarctica and for interpreting sedimentary records of cryosphere evolution. Here we develop a graph based approach, GraphSSeT, to model subglacial fluvial sedimentary transport using subglacial hydrology model outputs as forcing. GraphSSeT includes glacial erosion of bedrock and a dynamic sediment model with exchange between the active transport system and a basal sediment layer. Sediment transport considers transport-limited and supply-limited regimes and includes stochastically-evolving grain size, network scale flow management and tracking of detrital provenance. GraphSSeT satisfies volume balance and sediment velocity and transport capacity constraints on flow. GraphSSeT is demonstrated for synthetic scenarios that probe the impact of variations in hydrological, geological and glaciological characteristics on sediment transport over multi-diurnal to seasonal timeframes. For steady-state hydrology scenarios on seasonal timescales we find a primary control from the scale and organisation of the channelised hydrological flow network. The development of grain size dependant selective transport is identified as the major secondary control. Non-steady-state hydrology is tested on multi-diurnal timescales, for which sediment discharge scales with peak water input leading to increased sediment discharge compared to steady state. With increasing application of subglacial hydrology models, GraphSSeT extends this capacity to define quantitatively the volume, grain size distribution and detrital characteristics of sediment discharge, and enables a stronger connection of models of the glacio-hydrological system with constraints from the sediment record and impacts on marine systems. [ABSTRACT FROM AUTHOR]

The Niangmuco region on the east margin of the Eastern Himalayan Syntaxis features a large number of glacial lakes. The development process and stability classification of glacial lakes is of great significance to the study of seasonal glaciers in the eastern Himalayan margin, with implications for economic development and disaster prevention. Based on Landsat remote sensing image data from 2000 to 2021, this study analyzed the development and change characteristics of glacial lakes in the Niangmuco region during the past 21 years, and classified the stability of lakes with areas >0.02 km² using the fuzzy consistent matrix method. In this area, 126 glacial lakes were identified within an elevation range of 3044-4156 m with a total area of 10.94 km². These lakes primarily included glacial erosion lakes, valley lakes, tectonic lakes, and landslide dam lakes. Specifically, glacial erosion lakes accounted for 88.9% of the total number of lakes and 60.3% of the total lake area, followed by valley lakes with 6.3% and 23.7%, respectively. From 2000 to 2010, the total area of glacial lakes decreased from 10.53 km² to 10.09 km², which may be attributable to climate fluctuations. Subsequently, the area of lakes increased significantly to 10.94 km² in 2021, an increase of 0.41 km². Compared with 2000, among the lakes with a growth rate of 0.019 km²/a in 21 years, glacial erosion lakes exhibited the largest change. Among the classified glacial lakes in the study area, 95.7% were stable and relatively stable, mostly comprising glacial erosion lakes at high altitudes between 3468 and 4156 m. Only 4 unstable and extremely unstable glacial lakes were identified, and they were located near a fault zone. The findings show that the development and the change of glacial lakes in the area are primarily controlled by temperature and precipitation, and the topography and fault activity have important influences on the stability of glacial lakes. [ABSTRACT FROM AUTHOR]

While glacial remnants in the form of viscous flow features in the mid-latitudes of Mars are considered to be cold-based in the present-day, an increasing amount of geomorphic evidence suggests that at least some flow features were previously wet-based or had a mixed thermal state (polythermal) at during their evolution. Many of the viscous flow features known as glacier-like forms have been observed to emerge from alcoves that appear similar to cirques on Earth. Terrestrial cirques are typically characterized by a concave basin connected to a steep backwall. Cirques are expected to form from depressions in mountainsides that fill with snow/ice and over time support active glaciers that deepen the depressions by wet-based glacial erosion. To assess which alcoves on Mars are most "cirque-like", we mapped a population of ~2000 alcoves in Deuteronilus Mensae, a region in the mid-latitudes of Mars characterized by mesas encompassed by glacial remnants. Based on visual characteristics and morphometrics, we refined our dataset to 386 "cirque-like alcoves", which is five times the amount of glacier-like forms in the region, and used this to assess the past extent and style of glaciation on Mars. Using high resolution imagery, we find geomorphic evidence for glacial occupation associated with the cirque-like alcoves, including crevasse-like features, surface lineations, polygonal terrain, and moraine-like ridges. We propose that the cirque-like alcoves with icy remnants similar to rock glaciers on Earth represent a late stage of glacier-like form evolution. We also outline stages of cirque-like alcove evolution, linking a potential early stage of cirque-like alcoves to gully activity. On a population-wide scale, the cirque-like alcoves have a south to southeastward aspect bias, which may indicate a requirement for increased insolation for melting to occur and a connection to gullies on Mars. While the alcoves also have similarities to other features such as landslide scarps and amphitheater-headed valleys, the cirque-like alcoves have unique morphologies and morphometrics that differentiate their origin. Assuming warm-based erosion rates, the cirque-like alcoves have timescales consistent with both glacier-like forms and other viscous flow features like lobate debris aprons, whereas cold-based erosion rates would only allow the older timescales of lobate debris aprons. We propose that based on the geomorphic features and southward aspect, cirque-like alcove formation is more consistent with warm-based glaciation. [ABSTRACT FROM AUTHOR]

The article presents a method and applications for an anti-erosion management formula, based on the neutral-inclusive characteristics of the organization and management of glacial processes and phenomena. It is shown that the study of soil erosion under the influence of the glacial formations and the study of the glacial erosion itself have complexity. The organization and the anti-erosion arrangement for both cases implies the real procedural knowledge, the disposition in verifiable conceptual instruments and managerial actions / solutions of a neutral-inclusive nature. The general knowledge of the erosion phenomenon, invoked in the field, provides the premises for research regarding glacial-pedological erosion, specific to the continental areas, including for Romania, in the Carpathian Mountains area. By investigating the glacial relief in Romania and identifying sub-processes and glacial processes, a relational image could be elaborated expressing the occurrence / manifestation of glacial-pedological erosion. The concept and method presented in the article can be complemented by the extension of the research in the field regarding the specific aspects of the global erosion processess, but also with the local, mountain, intramontane ones from the geographical areas with continental and polar climate. An important step in this article is to devise a method of formalizing a geo-glacial "atlas" starting from "maps" of real-glacial sub-areas, demonstrating their conditions of injectivity and differentiability. Further, a qualitative performance indicator could be established for comparing the movements of the glacial formations on the mountain / intramontal surface of Romania with the standard, measurable and controllable displacements, aiming at the zonal protection in front of the geo-glacial incidents. [ABSTRACT FROM AUTHOR]

The last deglaciation is the most recent relatively well-documented period of pronounced and fast climate warming, and, as such, it holds important information for our understanding of the climate system. Notably, while research into terrestrial organic carbon reservoirs has been instrumental in exploring the possible sources of atmospheric carbon dioxide during periods of rapid change, the underlying mechanisms are not fully understood. Here we investigate the mobilization of organic matter to the Bay of Biscay, located in the north-eastern Atlantic Ocean off the coasts of France and Spain. Specifically, we focus on the area that was the mouth of the Channel River during the last deglaciation, where an enhanced terrigenous input has been reported for the last glacial–interglacial transition. We conducted a comprehensive suite of biomarker analyses (e.g. n-alkanes, hopanes and n-alkanoic acids) and isotopic investigations (radiocarbon dating and δ13 C measurements) on a high-resolution sedimentary archive. The present study provides the first direct evidence for the fluvial supply of immature and ancient terrestrial organic matter to the core location. Moreover, our results reveal the possibility of permafrost carbon export to the ocean, driven by processes such as deglacial warming and glacial erosion. These findings are consistent with observations from other regions characterized by present or past permafrost conditions on land, which have shown that permafrost thaw and glacial erosion can lead to carbon remobilization, potentially influencing atmospheric carbon dioxide levels. [ABSTRACT FROM AUTHOR]

The Matterhorn, a famous mountain in the Swiss Alps is a well characterized geomorphosite, presenting both an important scientific interest and aesthetic, cultural and economic values in Switzerland. The main scientific issues concerning the Matterhorn are its place in the tectonic history of the Alps, the carving of a residual pyramid by glacial erosion and the effects of melting of high mountain permafrost on mountaineering. To answer those questions, two “tools” were used, the field work and the bibliographic investigations. The Matterhorn played, from its first ascent in 1865 until today, a very special role in the history of mountaineering, and its remarkable shape has become iconic in Switzerland. As a consequence, the Matterhorn can be analyzed through four time scales:(1) the deep time of tectonics during the Cenozoic era, which saw the thrusting and piling up of the “Pennine nappes,” due to the collision between African and European plates; (2) the Quaternary period of glacial erosion, which carved the Matterhorn into its distinctive pyramidal peak shape;(3) the Anthropocene time of the thawing of high mountain permafrost; and (4) the era of humans or mountaineering, which spans over than 150 years, from the first ascent in 1865 to the recent achievements of modern mountaineering.

We investigated the mechanisms leading to the formation of tunnel valleys in the Swiss foreland near Bern. We proceeded through producing 3D maps of the bedrock topography based on drillhole information and a new gravimetric survey combined with modelling. In this context, the combination of information about the densities of the sedimentary fill and of the bedrock, together with published borehole data and the results of gravity surveys along 11 profiles across the valleys, served as input for the application of our 3D gravity modelling software referred to as PRISMA. This ultimately allowed us to model the gravity effect of the Quaternary fill of the overdeepenings and to produce cross-sectional geometries of these troughs. The results show that 2–3 km upstream of the city of Bern, the overdeepenings are approximately 3 km wide. They are characterized by steep to oversteepened lateral flanks and a wide flat base, which we consider as a U-shaped cross-sectional geometry. There, the maximum residual gravity anomaly ranges between − 3 to − 4 mGal for the Aare valley, which is the main overdeepening of the region. Modelling shows that this corresponds to a depression, which reaches a depth of c. 300 m a.s.l. Farther downstream approaching Bern, the erosional trough narrows by c. 1 km, and the base gets shallower by c. 100 m as revealed by drillings. This is supported by the results of our gravity surveys, which disclose a lower maximum gravity effect of c. − 0.8 to − 1.3 mGal. Interestingly, in the Bern city area, these shallow troughs with maximum gravity anomalies ranging from − 1.4 to − 1.8 mGal are underlain by one or multiple inner gorges, which are at least 100 m deep (based on drilling information) and only a few tens of meters wide (disclosed by gravity modelling). At the downstream end of the Bern area, we observe that the trough widens from 2 km at the northern border of Bern to c. 4 km approximately 2 km farther downstream, while the bottom still reaches c. 300 to 200 m a.s.l. Our gravity survey implies that this change is associated with an increase in the maximum residual anomaly, reaching values of − 2.5 mGal. Interestingly, the overdeepening's cross-sectional geometry in this area has steeply dipping flanks converging to a narrow base, which we consider as V-shaped. We attribute this shape to erosion by water either underneath or at the snout of a glacier, forming a gorge. This narrow bedrock depression was subsequently widened by glacial carving. In this context, strong glacial erosion upstream of the Bern area appears to have overprinted these traces. In contrast, beneath the city of Bern and farther downstream these V-shaped features have been preserved. Available chronological data suggest that the formation of this gorge occurred prior to MIS 8 and possibly during the aftermath of one of the largest glaciations when large fluxes of meltwater resulted in the fluvial carving into the bedrock. [ABSTRACT FROM AUTHOR]

Reconstructions of the southwestern Laurentide Ice Sheet (LIS) from geomorphology have revealed complex cross‐cutting ice streams, indicative of surging and flow switching. This flow pattern and behaviour is distinct from the rest of the ice sheet where ice streams flowed radially to the ice sheet margin. Many ice streams in the southwestern sector originate around the Alberta Oil Sands (AOS). Previous reports have detected oil sands material in surficial and glacial sediments south of the AOS, demonstrating potential glacial mobilisation of the oil sands. In this study, we use geochemical fingerprinting to systematically investigate surficial sediments from the former Central Alberta Ice Stream (CAIS) flow track. We compare the geochemical signatures of 82 sediments from within and outside the CAIS limits with those of the AOS (from mines and natural exposures), using gas chromatography–mass spectrometry oil–oil correlation techniques. Our results provide geochemical evidence of glacial erosion and long‐distance mobilisation of AOS producing contamination signatures in sediments throughout the CAIS flow track. The strength of the AOS signature is particularly strong in sediments along the terminating margins, to the east of Calgary and in the Cooking Lake area to the southeast of Edmonton. These results inform theoretical models of enhanced slipperiness, inspired by slippery liquid infused porous surfaces (SLIPS), whereby oil lubrication of the basal sediment influences the degree of sliding and basal deformation in the ice stream. We hypothesise that naturally occurring hydrocarbons at the basal interface exerted control on the location of the onset zone of the CAIS and surrounding ice streams in Alberta. The enhanced slipperiness caused by oil contamination may also explain ice streaming and surging in other ice sheets, such as the Barents Sea Ice Sheet, where hydrocarbons are known to have been driven to the sedimentary interface during glaciation. [ABSTRACT FROM AUTHOR]

Glacial erosion rates on the Iceland landscape throughout the Pleistocene are not well quantified. Ice scour lakes provide an opportunity to investigate glacial erosive activity and relative intensity because they commonly form in areas beneath ice sheets due to intense quarrying. This study evaluates ice scour lake morphology and density as a potential proxy for paleo‐ice flow direction and basal thermal regime for parts of the Iceland Ice Sheet. Using GIS analysis, properties of ice scour lakes are examined in regions that experienced different rates of ice flow during and following the Last Glacial Maximum (LGM), as interpreted from streamlined subglacial landforms. The primary input datasets were topographic, hydrologic and bedrock data. Lake distribution and morphology were quantified for all natural lakes of Iceland (n = 30 169), with close examination of three 400 km2 sub‐regions in Vestfirðir (n = 904), Húnaflói (n = 69) and Bakkaheiði (n = 232). Lake distribution parameters include density, packing and centroid elevation. PolyMorph‐2D was used to quantify lake morphology including orientation, area and elongation ratio. Ice scour lake density, packing and elevation were all greatest on Vestfirðir. The high density and packing of lakes across Vestfirðir suggests unique ice dynamics relative to the other two sub‐regions, and multidirectional flow of lake axes supports the presence of an independent ice cap covering Vestfirðir. Differential intensity of glacial erosion interpreted from regions of high and low lake density on Bakkaheiði supports a proposed ice divide in Northeast Iceland. The orientation of lakes align with the flow directions of proposed LGM ice streams in Northern and Northeast Iceland. Ice scour lakes were most elongate on average on Bakkaheiði, which supports fast ice flow. Improving understanding of former ice sheet basal thermal regime and paleo‐ice flow velocity serves to inform modern controls on ice sheet stability and ice sheet basal processes. [ABSTRACT FROM AUTHOR]

The Matterhorn, a famous mountain in the Swiss Alps is a well characterized geomorphosite, presenting both an important scientific interest and aesthetic, cultural and economic values in Switzerland. The main scientific issues concerning the Matterhorn are its place in the tectonic history of the Alps, the carving of a residual pyramid by glacial erosion and the effects of melting of high mountain permafrost on mountaineering. To answer those questions, two “tools” were used, the field work and the bibliographic investigations. The Matterhorn played, from its first ascent in 1865 until today, a very special role in the history of mountaineering, and its remarkable shape has become iconic in Switzerland. As a consequence, the Matterhorn can be analyzed through four time scales:(1) the deep time of tectonics during the Cenozoic era, which saw the thrusting and piling up of the “Pennine nappes,” due to the collision between African and European plates; (2) the Quaternary period of glacial erosion, which carved the Matterhorn into its distinctive pyramidal peak shape;(3) the Anthropocene time of the thawing of high mountain permafrost; and (4) the era of humans or mountaineering, which spans over than 150 years, from the first ascent in 1865 to the recent achievements of modern mountaineering. [ABSTRACT FROM AUTHOR]

Glacial erosion creates diagnostic landscapes and vast amounts of sediment. However, knowledge about the rate at which glaciers erode and sculpt bedrock and the proportion of quarried (plucked) versus abraded material is limited. To address this, we quantify subglacial erosion rates and constrain the ratio of quarrying to abrasion during a recent, ∼ 200-year long overriding of a bedrock surface fronting, Sermeq Kujalleq (Jakobshavn Isbræ), Greenland, by combining 10 Be analyses, a digital terrain model, and field observations. Cosmogenic 10 Be measurements along a 1.2 m tall quarried bedrock step reveal a triangular wedge of quarried rock. Using individual 10 Be measurements from abraded surfaces across the study area, we derive an average abrasion rate of 0.13 ± 0.08 mm yr -1. By applying this analysis across a ∼ 1.33 km 2 study area, we estimate that the Greenland Ice Sheet quarried 378 ± 45 m 3 and abraded 322 ± 204 m 3 of material at this site. These values result in an average total erosion rate of 0.26 ± 0.16 mm yr -1 , with abrasion and quarrying contributing in roughly equal proportions within uncertainty. Additional cosmogenic 10 Be analysis and surface texture mapping indicate that many lee steps are relicts from the prior glaciation and were not re-quarried during the recent overriding event. These new observations of glacier erosion in a recently exposed landscape provide one of the first direct measurements of quarrying rates and indicate that quarrying accounts for roughly half of the total glacial erosion in representative continental shield lithologies. [ABSTRACT FROM AUTHOR]

The subglacial landscape of Antarctica records and influences the behaviour of its overlying ice sheet. However, in many places, the evolution of the landscape and its control on ice sheet behaviour has not been investigated in detail. Using recently released radio-echo sounding data, we investigate the subglacial landscape of the Evans-Rutford region of West Antarctica. Following quantitative analysis of the landscape morphology under ice-loaded and unloaded conditions, we identify ten flat surfaces distributed across the region. Across these ten surfaces, we identify two distinct populations based on clustering of elevations, which potentially represent remnants of regionally coherent pre-glacial surfaces underlying the West Antarctic Ice Sheet (WAIS). The surfaces are bounded by deeply incised glacial troughs, some of which have potential tectonic controls. We assess two hypotheses for the evolution of the regional landscape: (1) passive margin evolution associated with the breakup of the Gondwana supercontinent, or (2) an extensive planation surface that may have been uplifted either in association with the West Antarctic Rift System or cessation of subduction at the base of the Antarctic Peninsula. We suggest that passive margin evolution is most likely of these two mechanisms, with the erosion of glacial troughs adjacent to, and incising, the flat surfaces likely having coincided with the growth of the WAIS. These flat surfaces also demonstrate similarities to other identified surfaces, indicating that a similar formational process may have been acting more widely around the Weddell Sea Embayment. The subsequent fluctuations of ice flow, basal thermal regime and erosion patterns of the WAIS are therefore controlled by the regional tectonic structures. [ABSTRACT FROM AUTHOR]

Examining the links and potential feedbacks between tectonics and climate requires understanding the processes and variables controlling erosion. At the orogen scale, tectonics and climate are thought to be linked through the influence of mountain elevation on orographic precipitation and glaciation; the only documented erosional processes capable of balancing rapid rock‐uplift rates are glacial erosion or coupled river incision and landsliding. Our 20 new 10Be derived catchment‐averaged denudation rates from the Western Southern Alps of New Zealand generally range between 0.6 and 9 mm/yr, within the same order of magnitude as fault‐throw rates, exhumation rates, and erosion rates estimated from suspended sediment yields and landslide inventories. Combining our data with previously published 10Be denudation rates, we find that the proportion of catchment area in the 1,500–2,000 m elevation window is the variable that best explains denudation rate variability and the disparity between rock‐uplift rates and denudation rates. This correlation indicates that enhanced erosion likely occurs at 1,500–2,000 m above sea level, where periglacial and paraglacial processes have been proposed to be most active. We find that these temperature‐controlled erosional processes, which are also elevation‐dependent, can play a greater role in modulating erosion during interglacials than precipitation or glaciation. Our data suggest that temperature‐controlled peri‐ and paraglacial erosion could be efficient enough to balance some of the fastest rock‐uplift rates on Earth. Hence, temperature‐controlled erosion could contribute to limiting orogen elevations and modulating the erosion rates dictated by rock‐uplift, playing an essential role in linking tectonics and climate. Plain Language Summary: The shape and evolution of the Earth Surface depend on how the tectonic forces that build up mountains interact with the processes that wear them down through erosion. These erosional processes are often regulated by climate; for example, erosion is commonly more efficient where there are glaciers or in the wetter side of mountain ranges. We present 20 new 10Be concentrations, which are commonly used as a proxy for how fast drainage basins erode, from the Western Southern Alps of New Zealand, one of the fastest‐eroding places on Earth. We find that the rate at which these drainage basins erode is best predicted by the proportion of their drainage area that falls within the 1,500–2,000 m above sea‐level elevation window. This elevation range had previously been suggested to be where rocks are damaged and eroded through freeze‐thaw cycles. It is also the elevation window from which glaciers are currently retreating or have recently retreated, which can intensify erosion. Both freeze‐thaw cycles and glacier retreat depend on elevation and are related to temperature; therefore, we infer that temperature‐controlled erosional processes have likely dominated erosion for the last decades to hundreds of years. Key Points: Twenty new 10Be denudation rates of Western Southern Alps catchments are in the range 0.6–9 mm/yr, and likely >9 mm/yr for two glaciated catchmentsThe proportion of catchment area at 1,500–2,000 masl is the variable that best correlates with observed denudation‐rate variabilityElevation sensitivity of denudation is most likely due to peri‐ and paraglacial processes that modulate the tectonic control on erosion [ABSTRACT FROM AUTHOR]

ABSTRACTWe present the first extensive high-resolution glacial geomorphic map west of the Andean Cordillera in southernmost Chile (52.8–53.1°S, 73.0–73.9°W). The map extends over 1565 km2 and is based on high-resolution satellite images and aerial photographs. At selected locations, the remotely mapped geomorphology was corroborated by field observations. The study area is dominated by glacial erosional landforms (77%) over depositional landforms (23%), with published submarine depositional landforms having been included (e.g. moraines). Glacial drift, kettle kame topography and lateral and frontal moraines form the primary depositional landforms and sediment associations. Glacial cirques, wide U-shaped valleys, whalebacks, roches moutonnées and scoured bedrock characterize most of the mapped area. The spatial distribution of whalebacks and roches moutonnées in the study area indicates a lack of lithological control on their formation and a warm-based, dynamic ice velocity and thickness regime during Patagonian Ice Sheet cover and retreat during the last glacial cycle.

Fjords are common geomorphological coastal features in the mid- and high-latitudes, carved by glacial erosion. These deep nearshore zones connect watersheds and oceans, typically behaving as an estuary. Many fjords in the world have shown concerning warming and deoxygenation trends in their deep waters, sometimes at faster rates than the open ocean. While that is the case in several fjords of British Columbia (BC), Canada, some of the same fjords have shown that strong Arctic outflow wind events in winter can lead to cooling and reoxygenation of subsurface waters, with effects lasting until the following autumn. The latter was observed in Bute Inlet, BC in 2019. We used a high-resolution, three-dimensional ocean model to investigate the mechanisms allowing for the persistence of these subsurface conditions through the year. The presence of the subsurface cold water mass reduced the already weak residual circulation, changing its vertical structure from three to four layers. The reduction of mixing and advection allowed for the water mass to stay in place until autumn conditions arrived (i.e., strong wind mixing and reduced freshwater forcing). The identification of mechanisms that allow for the persistence of cold and oxygenated conditions are key to understand potential areas of ecological refugia in a warming and deoxygenating ocean. [ABSTRACT FROM AUTHOR]

Bed topography is a critical parameter for determining the modern-day and future dynamics of ice sheets and their outlet glaciers. This is because the topography controls the state of stress for glaciers. At glacier termini, topography can influence the timing of terminus retreat by controlling access to warm ocean waters and/or by influencing the ability of a glacier terminus to retreat over bed bumps (moraines). Inland from the terminus, the topography can also influence where glacier retreat and thinning can stabilize. In part, this is because of knickpoints in bed topography created through glacial erosion that may influence the extent to which thinning can diffuse inland for an individual glacier and thus, the timing and magnitude of long-term mass loss. Here we provide a review of the current literature on these topics. While much of the reviewed literature assumes that topography is stable on relevant timescales to humans, new research suggests that topography may change much faster than previously thought and this further complicates our ability to project future outlet glacier change. [ABSTRACT FROM AUTHOR]

This paper addresses the effect of fractures within crystalline bedrock on glacial erosion processes in fast flowing hard bed glacier environments. In particular, we examine (i) whether the fracture type is critical for the capability of a glacier to erode the bedrock through quarrying/plucking processes and (ii) whether we can recognize specific fracture‐controlled erosion signatures from bedrock surface morphologies. We conducted an investigation within the northern part of the Åland Islands, southern Finland, where the ice‐flow direction (N–S) has remained constant through Late Pleistocene glaciations and where the bedrock is characterized by a lack of any mesoscopic anisotropies (such as foliation) and hence provides an optimal target to recognize the relationships between fractures and erosional morphologies. We characterized the fracture systems within the bedrock using both UAV‐acquired orthophotographs and standard field approaches and extrapolated the results to larger scales using LiDAR‐based digital elevation models. Our findings indicate that individual joints or shear fractures are associated with the development of minor vertical breaks along the bedrock surface. However, they do not provide sufficient mechanical weakness zones in the bedrock to allow effective glacial quarrying, even though their lengths can be relatively large (>50 m). By contrast, the linkage of several parallel shear fractures or the presence of larger faults with gouge‐bearing cores and well‐developed damage zones leads to localized disintegration of the rock material and the subsequent development of distinct topographic depressions along the bedrock surface. Consequently, the results allow predictions to be made about the bedrock features underlying the observed topographic signatures along the bedrock surface. Applied to the area of this investigation, abrasion associated with N–S‐directed glacial flows is responsible for the N–S‐oriented elongate but smooth fjord‐like megagrooves, whereas the more abrupt topographic breaks were generated by quarrying controlled by sub‐vertical, E–W‐trending zones of localized brittle deformation. [ABSTRACT FROM AUTHOR]

We introduce the first solution for simulating the formation and evolution of glaciers, together with their attendant erosive effects, for periods covering the combination of glacial and inter-glacial cycles. Our efficient solution includes both a fast yet accurate deep learning-based estimation of highorder ice flows and a new, multi-scale advection scheme enabling us to account for the distinct time scales at which glaciers reach equilibrium compared to eroding the terrain. We combine the resulting glacial erosion model with finer-scale erosive phenomena to account for the transport of debris flowing from cliffs. This enables us to model the formation of terrain shapes not previously adequately modeled in Computer Graphics, ranging from U-shaped and hanging valleys to fjords and glacial lakes. [ABSTRACT FROM AUTHOR]

Eolian loess deposits contain valuable information about past climate changes and erosion history in dust source regions. In contrast to the extensive investigations of paleoclimatic implications of Eurasian loess, continental erosion information in the loess deposits has received less attention, particularly on the global or hemispheric scales. The present study combines citrate‐bicarbonate‐dithionite (CBD) magnetic mineral extraction procedures and linear regression of magnetic parameters to analyze Eurasian loess. We find that lithogenic susceptibility of Quaternary loess deposits in Central Asia, Europe and the Chinese Loess Plateau shows synchronous long‐term increases since ∼0.6–0.5 Ma, suggesting intensive glacial erosion and/or river incision to have occurred in the surrounding mountains of dust source regions after the mid‐Pleistocene climate Transition. The dramatic increase in lithogenic susceptibility of Eurasian loess provides new insights into the close relationships between global climate changes and dust source erosion since the late Cenozoic. Plain Language Summary: Eolian loess deposits are valuable materials for elucidating the development and mechanisms of dust activities in Eurasia and their links with global climate changes and erosion processes in mountainous areas of dust sources on tectonic and orbital time scales. Continental erosion information retrieved from the Eurasian loess, however, has rarely been reported. A comprehensive analysis of lithogenic magnetic signals in Eurasian loess through mathematical and CBD extraction approaches demonstrates that lithogenic susceptibility of Quaternary loess‐paleosol sequences in Eurasia increased significantly after ∼0.6–0.5 Ma, in coincidence with increasing global ice volume and climatic instability after the mid‐Pleistocene climate Transition (MPT). We suggest that increased ice volume and climate fluctuation amplitudes after the MPT produced vast amounts of fresh Fe‐bearing silicate particles and detrital magnetite in mountainous areas of Eurasia, which can be attributed to a dramatic intensification of glacial erosion and river incision, thereby causing the loess lithogenic susceptibility increase. The results demonstrate that variations in lithogenic magnetic properties of loess deposits can be used to reconstruct the erosional history of main mountains surrounding the dust source regions in Eurasia over geological timescales. Key Points: Lithogenic magnetic susceptibility of Quaternary loess deposits in Eurasia increased synchronously after ∼0.6–0.5 MaGlobal cooling may account for the increase in lithogenic susceptibility of Eurasian loessSpatial variations of lithogenic susceptibility of Eurasian loess are related to varying distances between the source and the sink region [ABSTRACT FROM AUTHOR]

On the southwest cape of the Congo craton, a subtropical carbonate bank the size of Greenland was heavily glaciated during two Cryogenian panglacial episodes spaced 10–20 Myr apart. In NW Namibia, the bank underwent crustal stretching with resultant Aegean Sea-type topography during the older and longer Sturtian glaciation (717–661 Ma). This is indicated by angular discordance between glacial and preglacial strata and diamictites sourced from all older units, including crystalline basement. In contrast, the bank was flat-topped and underwent broad thermal subsidence during Marinoan glaciation (646 ± 5–635 Ma), attested by stratal parallellism and diamictites sourced from ≤100 m stratigraphic depth. However, ≥2.0 km of relief existed on the Marinoan continental slope, where most glacial erosion and accumulation occurred. The average rates of Marinoan erosion (2.55–6.80 m/Myr, n = 190) and accumulation (2.65–7.07 m/Myr, n = 211) are indistinguishable, implying that the location in a continental promontory did not bias erosion over accumulation. The average accumulation rates for the Sturtian and Marinoan, scaled for different averaging times, including Marinoan uncertainty, are 3.95–4.93 m/Myr (n = 183) and 2.65–7.07 m/Myr (n = 190), respectively, suggesting that a Marinoan glacioeustatic coastal escarpment substituted for rift-related Sturtian basin-and-range topography. These slow rates, comparable to long-term pre-Quaternary accumulation rates on existing abyssal plains, reconcile glacial sedimentology with the feeble hydrologic cycle of snowball Earth. [ABSTRACT FROM AUTHOR]

The evolution of mountainous topography is the result of the interactions of climate, topography, and erosion. Glaciers are one of the most active erosional forces sculpting mountainous regions. However, our ability to understand this erosional force is limited by the controversy regarding the major factors controlling glacial erosion. We selected the Nianbaoyeze Shan, which is occupied by subcontinental glaciers (likely cold-based or polythermal glaciers) in the northeastern Tibetan Plateau, to study how erosion by alpine glaciers sculpts the landscape. We first applied a power law model (y = axb) fit to the cross-profiles of glacial valleys and analyzed the controlling factor of glacial erosion; we then identified the morphometric characteristics of the cirques to analyze the influencing factors, and investigated the development patterns of glacial valleys and cirques. Finally, we used hypsometry and the slope-altitude curves and reconstructed the palaeo-glacier surfaces and palaeo-Equilibrium Line Altitudes (ELAs) to determine if the glacial buzzsaw effect had impacted this glaciated region with subcontinental glaciers. Our findings show that ice flux is the main factor controlling glacial erosion. In this region, decreasing temperatures promote an increase in glacier mean size (i.e., ice flux), which enhances the rate of glacial erosion. Cirque morphology is mainly influenced by aspect and the ELA. The development patterns of glacial valleys and cirques were dominated by a widening process. The ELAs of Marine Isotope Stage (MIS)-3 derived from the cirque floor altitudes or the Accumulation Area Ratio (AAR) and Area-Altitude Balance Ratio (AABR) coincide with the hypsometric maximum and the reduction in slope-altitude curves, which indicates that glacial buzzsaw has impacted this region. Furthermore, the glacial buzzsaw effect has profoundly influenced the mountain heights and topographic evolution in this subcontinental glaciated region. [ABSTRACT FROM AUTHOR]

Climate and environmental changes in the Arctic Ocean due to global warming have been linked to extreme climate change in mid-latitude regions, including the Korean Peninsula, requiring a better understanding of the Arctic climate system based on the paleo-analog. This review introduces three paleoenvironmental research cases using neodymium isotopes (143Nd/144Nd, εNd) measured on two different fractions of marine sediments: silicate-bound ‘detrital’ and Fe-Mn oxide-dominated ‘authigenic’ fractions. In the first case, detrital εNd in core HH17-1085-GC on the continental shelf off northern Svalbard was used for tracing changes in sediment provenance and associated glacier behavior over the last 16.3 ka. The second case showed the potential use of authigenic εNd as a quasi-conservative water mass tracer. Three prominent εNd peaks and troughs observed in core PS72/410-1 from the Mendeleev Ridge in the western Arctic Ocean over the past 76 ka suggested episodic meltwater discharge events during 51~46, 39~35 and 21~13 ka BP. The last case proposed the use of the difference between authigenic and detrital εNd as a proxy for reconstructing glacier fluctuation. The idea is based on the assumption that enhanced glacial erosion during glacier advances can supply sufficient freshly-exposed rock substrate for incongruent weathering, potentially leading to greater isotopic decoupling between bedrock and dissolved weathering products as recorded in detrital and authigenic εNd, respectively. Thus, it would be worthwhile to take advantage of sedimentary εNd to improve our understanding of past environmental changes in polar regions. [ABSTRACT FROM AUTHOR]

Glacial erosion creates diagnostic landscapes and vast amounts of sediment. Yet, knowledge about the rate by which glaciers erode and sculpt bedrock and the proportion of quarried (plucked) versus abraded material is limited. To address this, we quantify subglacial erosion rates and constrain the ratio of quarrying to abrasion during the 19th/20th century overriding of a bedrock surface fronting Jakobshavn Isbræ, Greenland, by combining 10Be analyses, a digital terrain model, and field observations. Cosmogenic 10Be measurements along a 1.2-m-tall quarried bedrock step reveal a triangular wedge of quarried rock. Using individual 10Be measurements from abraded surfaces across the study area, we derive an average abrasion rate of 0.13±0.08 mm yr-1. By applying this analysis across a ~1.33 km2 study area, we estimate that the Greenland Ice Sheet quarried 378±45 m3 and abraded 322±204 m3 of material at this site. These values result in an average total erosion rate of 0.26±0.16 mm yr-1 with abrasion and quarrying contributing in roughly equal proportions within uncertainty. Additional cosmogenic 10Be analysis and surface texture mapping indicate that many lee steps are relict from the prior glaciation and were not re-quarried during the recent overriding event. These new observations of glacier erosion in a recently exposed landscape provide one of the first direct measurements of quarrying rates and indicate that quarrying accounts for roughly half of total glacial erosion in representative continental shield lithologies. [ABSTRACT FROM AUTHOR]

Although Yosemite Valley, USA, catalyzed the modern environmental movement and fueled foundational debates in geomorphology, a century of investigation has failed to definitively determine when it formed. The non-depositional nature of the landscape and homogeneous bedrock have prevented direct geological assessments. Indirect assumptions about the age of downcutting have ranged from pre-Eocene to Pleistocene. Clarity on this issue would not only satisfy public interest but also provide a new constraint for contentious debates about the Cenozoic tectonic and geomorphologic history of the Sierra Nevada in California. Here we use thermochronometric analysis of radiogenic helium in apatite crystals, coupled with numerical models of crustal temperatures beneath evolving topography, to demonstrate significant late Cenozoic deepening of Tenaya Canyon, Yosemite's northeastern branch. Approximately 40%-90% of the current relief has developed since 10 Ma and most likely since 5 Ma. This coincides with renewed regional tectonism, which is a long-hypothesized but much debated driver of Sierran canyon development. Pleistocene glaciation caused spatially variable incision and valley widening in Yosemite Valley, whereas little contemporaneous erosion occurred in the adjacent upper Tuolumne watershed. Such variations probably arise from glacial erosion's dependence on topographic focusing of ice discharge into zones of rapid flow, and on the abundance of pre-existing fractures in the substrate. All available data, including those from our study, are consistent with a moderately high and slowly eroding mid-Cenozoic Sierra Nevada followed by significant late Cenozoic incision of some, but not all, west-side canyons. A likely driver of this event was range-crest uplift accompanied by fault-induced beheading of some major drainages, although other mechanisms such as drainage reorganization following volcanic deposition are plausible. [ABSTRACT FROM AUTHOR]

The ice crystal supercooled droplet mixed phase icing problem is an important research direction in aircraft icing and has received more attention in recent years. The thermodynamic process of the water film after the ice crystals impact on the surface determines the final ice shape, which is an important part of the accurate prediction of aircraft icing. In this paper, a thermodynamic model of ice crystal supercooled droplet mixed phase icing is proposed based on the extended Messinger model, according to the results of flow field and particle trajectory calculations. In this model, the mass and energy conservation equations of ice crystals, supercooled droplets, and liquid water are considered. The equations take the process of ice crystal adhesion and erosion into account, and the solution method of the equations is given. Ice shapes are calculated under various ice crystal supercooled droplet mixed phase conditions and compared with experimental results to demonstrate the validity of the numerical method. The effects of ice crystal erosion rate, melting ratio, and adhesion coefficient on the calculation results are analyzed by a numerical method. The results show that the ice crystal erosion rate has little effect on the ice shape, while a larger melting ratio and adhesion coefficient lead to more ice accretion. [ABSTRACT FROM AUTHOR]

Glacial sediment research using thin sections began post-1945. Microsedimentology examines sediments at the microscopic level deriving insights into the processes of glacial erosion, transport, and deposition. Two issues exist (1) the difficulty by some in recognizing microstructures in thin section and (2) the absence of quantitative data making data reproduction difficult. The latter is hard to resolve but more image capture and software methodologies are now becoming available at reasonable costs. Thin sections are two-dimensional sections of three-dimensional objects, and this must be considered when measurements, fabrics and other data are assessed. Research into the microaspects of glacial sediments followed a typical scientific trajectory: thin sections description with little uniformity or common "language" for observed microstructures: standardization allowed comparison between different sediments; with standardization, came an open-ended classification; and with cross-comparison with multiple thin sections—a quantitative means of study needs developed. It has become apparent that the basic principles of structural geology had to be applied. Thus, micromorphology has subsumed into a microsedimentological study of glacial sediments where stress parameters, structural fabrics and the mapping of deformation structures and contextual integration allows an understanding of how these sediments have been formed. Examples of the development stages of glacial micromorphology/sedimentology are presented here as well as discussion of future avenues of study. In addition, multiple thin sections are used to illustrate the many aspects of glacial micromorphology and the parameters necessary to understand glacial sedimentology and the processes of glacial sedimentation. [ABSTRACT FROM AUTHOR]

Present-day global warming raises important issues regarding sediment flux from glaciated catchments. The detrital export from such environments results from erosion processes operating in three geomorphic domains: the supraglacial rockwalls, the ice-covered substratum and the proglacial area, downstream from the glacier. The dominant process controlling present-day sediment export from glaciated catchments remains debated with most studies underlining the paraglacial dynamics in the glacier forefront. This study nuances these observations by quantifying the contribution from each geomorphic domain to the export of a glaciated catchment in the North face of Mont-Blanc (France). High resolution hydro-sedimentary flux data were acquired during eight years in two proglacial streams with contrasting glacio-hydrological characteristics, Bossons and Crosette streams. In the Bossons stream catchment, the sediment response highlights the initiation of the dendritic drainage network beneath the glacier, the short-lived evacuation of an annual storage during the early melt-season and its subsequent steadier regime. In addition, three years exhibit late melt season exports which are uncorrelated with temperature or rainfall. The evolution of the drainage network throughout the melt season explains the evacuation of the annual and pluri-annual subglacial sediment stocks. In addition, glacial retreat in link with higher melt rate allows for exporting a pluri-annual sediment stock stored beneath the glacier. To conclude, the present-day sediment response in Bossons catchment displays distinct components with characteristic timescales and is dampened by intermediate storage controlled by drainage development and extreme events in the glacial and proglacial domains.

Copyright of Naturaliste Canadien is the property of La Societe Provancher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)