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We 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. [ABSTRACT FROM AUTHOR]

Roches moutonnées are typical landforms of glacial erosion developed in hard rocks, with an asymmetric profile caused by abrasion and lee-side plucking. In eastern Sweden, some roches moutonnées show extensive damage, including open fractures, disintegration into blocks, fracture caves and short boulder trains. Disintegration increases along ice-flow directions during deglaciation of the last Weichselian Fennoscandian Ice Sheet, indicating a subglacial origin: limited edge rounding can be explained by a combination of hard rock, slow abrasion rates and disintegration just prior to deglaciation. The roches moutonnées initially developed in kernels of gneissic rocks with a wide fracture spacing (large block size) and interlocking fracture pattern, and hence high overall rock mass strength. Dilated fractures and 'fracture caves' occur up to 15 m below the ice-bed interface. It is proposed that hydraulic jacking by overpressured water opened up the rock mass along pre-existing fractures. Jacking reduced rock mass strength, allowing glaciotectonic deformation of the roches moutonnées. Uneven hydraulic jacking led to uplift of individual fracture-bound blocks above the pre-existing smooth, abraded surface of the roches moutonnées, creating blunt, step-like edges. These edges allowed high ice pushing forces to act on large blocks: where blocks extend into the deeper rock mass, they further aided the disintegration of the rock mass. The disintegrated roches moutonnées can be regarded as transient features between intact bedrock and complete disintegration into boulders. The jacking-disintegration-transport sequence is characteristic of glacial ripping and very different from classic lee-side plucking. [ABSTRACT FROM AUTHOR]

Within the moss genus Timmia, three or four sections have been suggested based on morphology. Earlier studies conflicted in suggesting that T. austriaca Hedw. either displays limited phylogeographical structure or includes large molecular variation with potential for geographical structure. Relationships within Timmia were inferred from variation in the nuclear 26S and plastid atpB–rbcL and trnL–trnF. New sequences were generated for 64 specimens of T. austriaca. For other Timmia species, sequences came primarily from earlier studies or GenBank. Timmia includes two main, well-supported molecular lineages. Within T. austriaca, four arctic or subarctic specimens resolved in a small-lineage sister to all other specimens. Recognition of two sections is suggested: Timmia Hedw. sect. Timmia (syn. sect. Timmiaurea Brassard; syn. sect. Sphaerocarpa Y.Jia & Yang Liu bis) and sect. Norvegica Brassard. Timmia fossils, including T. austriaca, were deposited at least 3 Myr BP in northernmost North America under a milder climate than presently in that area. It is theorised that plants of the small T. austriaca lineage evolved adaptations to survive only under cold conditions, when the Arctic was gradually cooling. Timmia austriaca disperses easily, and because the numerous temperate region samples studied included no representatives of the northern lineage, the restricted distribution of this lineage is suggested to have resulted from adaptation to cold environments. In situ survival of T. austriaca in Fennoscandia during the Late Glacial Maximum, as previously theorised, is deemed unlikely due to glacial erosion and submergence of large areas as a result of isostatic depression. [ABSTRACT FROM AUTHOR]

This paper examines the geomorphological evolution of the Criffel–Dalbeattie granitic pluton (CDGP). Research is based on data from Shuttle Radar Topography Mission, Google Earth, Ordnance Survey maps and field measurements. Granitic emplacement into Southern Uplands terrain along Caledonian structural trends took place during the mid-late Devonian. Faulting and subsidence during the late Palaeozoic and Mesozoic preceded assumed differential uplift of the pluton during the early Palaeocene. This led to the development of bidirectional palaeo-surfaces. Structural rather than lithological controls formed the dominant bases for subsequent weathering during the Palaeogene and Neogene. Shallow surface weathering over the CDGP and absence of saprolite imply that weathering episodes may have been relatively short-lived. However, joint enlargement and in situ eroded corestones indicate that earlier weathered features were substantially modified by glacial agencies. Pleistocene glacial events included ice streaming from the NNW which took place over moulded hills. Thinner late-stage ice scoured irregular hill long profiles while divergent ice contributed to basin erosion. Localised resurgent ice streaming was shortlived. After early uplift and palaeo-surface formation, the CDGP hills evolved through phases of granitic weathering and glacial erosion likely over the past 65 Ma since the early Palaeocene. [ABSTRACT FROM AUTHOR]

In low relief Precambrian gneiss terrain in eastern Sweden, abraded bedrock surfaces were ripped apart by the Fennoscandian Ice Sheet. The resultant boulder spreads are covers of large, angular boulders, many with glacial transport distances of 1–100 m. Boulder spreads occur alongside partly disintegrated roches moutonnées and associated fracture caves, and are associated with disrupted bedrock, which shows extensive fracture dilation in the near surface. These features are distributed in ice-flow parallel belts up to 10 km wide and extend over distances of >500 km. Our hypothesis is that the assemblage results from (1) hydraulic jacking and bedrock disruption, (2) subglacial ripping and (3) displacement, transport and final deposition of boulders. Soft sediment fills indicate jacking and dilation of pre-existing bedrock fractures by groundwater overpressure below the ice sheet. Overpressure reduces frictional resistance along fractures. Where ice traction overcomes this resistance, the rock mass strength is exceeded, resulting in disintegration of rock surfaces and ripping apart into separate blocks. Further movement and deposition create boulder spreads and moraines. Short boulder transport distances and high angularity indicate that glacial ripping operated late in the last deglaciation. The depths of rock mobilized in boulder spreads are estimated as 1–4 m. This compares with 0.6–1.6 m depths of erosion during the last glaciation derived from cosmogenic nuclide inventories of samples from bedrock surfaces without evidence of disruption. Glacially disrupted and ripped bedrock is also made ready for removal by future ice sheets. Hence glacial ripping is a highly effective process of glacial erosion. [ABSTRACT FROM AUTHOR]

The present marine Baltic Sea basin (BSB) occupies an eroded Proterozoic intra-cratonic basin on the Fennoscandian shield. Competing models propose a Neogene fluvial origin, with later modification by glacial erosion, or a much younger development, with overdeepening beneath the Fennoscandian Ice Sheet (FIS). We test these alternatives using a first order source to sink sediment budget for the catchment of the BSB. Best estimates derived from geomorphic and cosmogenic nuclide evidence suggest depths of erosion over the last 1 Ma of 20 m in basement and 40 m in sedimentary rocks that surround the BSB. As the BSB has been overdeepened below a regional base level provided by the shallow Darss Sill at the boundary with the Kattegat, erosion of the BSB may be interpreted as glacial in origin, without a fluvial component. The estimated total volume of source area erosion is 30,628 km3 of which 87% is derived from the present BSB. Sediment volumes in the sink area within the limits of maximum Pleistocene glaciation are estimated at a minimum of 37,629 km3, after correction for local erosion, porosity, and carbonate losses. Marine Isotope Stage 12 and younger sediments account for 87% of the total Pleistocene sediment volume in the sink in Poland. Although significant uncertainties remain, the sediment budget is consistent with erosion of the BSB entirely by the FIS, mainly when the ice sheet reached its maximum extent and thickness during the Middle and Late Pleistocene glaciations. [ABSTRACT FROM AUTHOR]

Here, a geomorphological map of Horseshoe Island, which is one of the most ice-free islands in Marguerite Bay of the Antarctic Peninsula, is provided. The landforms on the island were mapped by using Google Earth images. Field reconnaissance of the landforms was carried out in March 2018. The island is subdivided into three major geomorphologically different sectors. The northern sector is mostly covered by a remnant of a non-erosive ice cap and has limited glacial landforms and deposits. The central sector is rich in terms of glacial and periglacial landforms and deposits. Glaciers are still sculpting the southern sector and it has extensive features of glacial erosion and deposition. The most common landforms on the island are talus cones, moraines, patterned ground, and raised beaches. The geomorphological map of the island will be a useful base for further geomorphic and/or glaciologic research in this climate-sensitive region. [ABSTRACT FROM AUTHOR]

The geometry of the upper-crustal portion of the Alpine Fault plate boundary on New Zealand's South Island, is poorly constrained where it cuts through the sedimentary units of the Westland coastal plain. Two seismic reflection and gravity lines are presented here to better image the upper km of the fault beneath the most recent fault rupture scarps south of the Haast River. Analysis of the seismic lines suggests that multiple fault strands have cut across post-glacial sedimentary strata that overlie the glacially eroded basement. Total combined fault offsets of 39 m at the Haast River and 33 m at the Turnbull River over <17 ka is consistent with previously determined uplift rates. Dip on the fault strands is interpreted to be between ∼53 and ∼76° SE. 2D gravity profiles constrain the interpretation of the interface between sedimentary units and basement, which has considerable 3D variability resulting from glacial erosion processes. [ABSTRACT FROM AUTHOR]

Concentrations of boulders are a common feature of landscapes modified by former mid-latitude ice sheets. In many cases, the origin of the boulders can be traced in the up-ice direction to a cliff only tens to hundreds of metres distant. The implication is that a pulse of plucking and short boulder transport occurred beneath thin ice at the end of the last glacial cycle. Here we use a case study in granite bedrock in the Dee Valley, Scotland, to constrain theory and explore the factors involved in such a late phase of plucking. Plucking is influenced by ice velocity, hydrology, effective ice pressure, the extent of subglacial cavities and bedrock characteristics. The balance between these factors favours block removal beneath thin ice near a glacier margin. At Ripe Hill in the Dee Valley, a mean exposure age of 14.2 ka on blocks supports the view that the boulder train formed at the end of ice sheet glaciation. The late pulse of plucking was further enhanced by ice flowing obliquely across vertical joints and by fluctuations in sub-marginal meltwater conditions. An implication of the study is that there is the potential for a wave of ice-marginal plucking to sweep across a landscape as an ice sheet retreats. [ABSTRACT FROM AUTHOR]

The geology of Tindfjallajökull volcano, southern Iceland, is presented as a 1:50,000 scale map. Field mapping was carried out with a focus on indicators of past environments. A broad stratocone of interbedded fragmental rocks and lavas was constructed during Tindfjallajökull's early development. This stratocone has been dissected by glacial erosion and overlain by a variety of mafic to silicic volcanic landforms. Eruption of silicic magma, which probably occurred subglacially, constructed a thick pile of breccia and lava lobes in the summit area. Mafic to intermediate flank eruptions continued through to the end of the last glacial period, producing lavas, hyaloclastite-dominated units and tuyas that preserve evidence of volcano-ice interactions. The Thórsmörk Ignimbrite, a regionally important chronostratigraphic marker, is present on the SE flank of the volcano. The geological mapping of Tindfjallajökull gives insights into the evolution of stratovolcanoes in glaciated regions and the influence of ice in their development. [ABSTRACT FROM AUTHOR]

We explore the relationships amongst bedding dip, basin aspect, and glacial landforms using field observations and GIS analyses of the northwestern Uinta Mountains of Utah. We examine basins on opposing sides of three ice divides in which quartzite beds of the Mount Watson Formation maintain a near constant dip. These areas provide contrasting relationships between ice flow and bedding dip directions while holding rock type and climate constant. We map the occurrence of three glacial erosional landforms: cliffs showing evidence of quarrying, scoured surfaces polished by abrasion, and overdeepenings. Cliffs and overdeepenings are more common in basins where bedding dips up-basin, while scoured surfaces are more prevalent where bedding dips down-basin. The significance of jointing in controlling glacial erosional forms is well established and we propose that bedding, as well as joints, dictates the geometry of quarried blocks and influences the spatial patterns of process dominance. Where bedding dips up-basin, the geometry of pre-existing weaknesses favours quarrying creating both cliffs and overdeepenings. In contrast, where bedding dips down-basin, block geometry does not favour the creation of overdeepenings via quarrying and exposed bedding planes are subjected to glacial abrasion, producing scoured surfaces. [ABSTRACT FROM AUTHOR]

Here we present datasets from a hydroacoustic survey in July 2011 at Lake Torneträsk, northern Sweden. Our hydroacoustic data exhibit lake floor morphologies formed by glacial erosion and accumulation processes, insights into lacustrine sediment accumulation since the beginning of deglaciation, and information on seismic activity along the Pärvie Fault. Features of glacial scouring with a high-energy relief, steep slopes, and relative reliefs of more than 50 m are observed in the large W-basin. The remainder of the lacustrine subsurface appears to host a broad variety of well preserved formations from glacial accumulation related to the last retreat of the Fennoscandian ice sheet. Deposition of glaciolacustrine and lacustrine sediments is focused in areas situated in proximity to major inlets. Sediment accumulation in distal areas of the lake seldom exceeds 2 m or is not observable. We assume that lack of sediment deposition in the lake is a result of different factors, including low rates of erosion in the catchment, a previously high lake level leading to deposition of sediments in higher elevated paleodeltas, tributaries carrying low suspension loads as a result of sedimentation in upstream lakes, and an overall low productivity in the lake. A clear off-shore trace of the Pärvie Fault could not be detected from our hydroacoustic data. However, an absence of sediment disturbance in close proximity to the presumed fault trace implies minimal seismic activity since deposition of the glaciolacustrine and lacustrine sediments. [ABSTRACT FROM AUTHOR]

The morphometry of glaciated valleys has been of considerable significance in evaluating models and processes of valley form development, and is typically evaluated using a power law function fit to topographic data. Results of the power law method are sensitive to the location of the coordinate system origin, but most previous research has used a coordinate system centered, on the valley midpoint and has not systematically assessed alternative approaches. Here, we test four options for selecting the coordinate system origin, using cross-section profiles from glacial, fluvial, and transitional valleys in the Dalijia Mountains, China: (A) the lowest elevation point, (B) the valley midpoint, (C) the lowest point on the valley side wall, and (D) the highest point on the valley side. Option A produces results that are most consistent with expected values and trends for shape parameters in the Dalijia Mountains. Over half of the values calculated using Option B overestimate key valley-shape parameters compared to Option A. Options C and D produce similar values to each other, but these values are very different from Option A and less useful for landform interpretation. In morphometric studies designed to evaluate impacts of glacial erosion using the power law approach, we recommend that alternate coordinate system origins be evaluated, including the lowest elevation point on a cross-profile. [ABSTRACT FROM AUTHOR]

We seek to quantify glacial erosion in a low relief shield landscape in northern Sweden. We use GIS analyses of digital elevation models and field mapping of glacial erosion indicators to explore the geomorphology of three granite areas with the same sets of landforms and of similar relative relief, but with different degrees of glacial streamlining. Area 1, the Parkajoki district, shows no streamlining and so is a type area for negligible glacial erosion. Parkajoki retains many delicate pre-glacial features, including tors and saprolites with exposure histories of over 1 Myr. Area 2 shows the onset of significant glacial erosion, with the development of glacially streamlined bedrock hills. Area 3 shows extensive glacial streamlining and the development of hill forms such as large crag and tails and roches moutonnées. Preservation of old landforms is almost complete in Area 1, due to repeated covers of cold-based, non-erosive ice. In Area 2, streamlined hills appear but sheet joint patterns indicate that the lateral erosion of granite domes needed to form flanking cliffs and to give a streamlined appearance is only of the order of a few tens of metres. The inheritance of large-scale, pre-glacial landforms, notably structurally controlled bedrock hills and low relief palaeosurfaces, remains evident even in Area 3, the zone of maximum glacial erosion. Glacial erosion here has been concentrated in valleys, leading to the dissection and loss of area of palaeosurfaces. Semi-quantitative estimates of glacial erosion on inselbergs and palaeosurfaces and in valleys provide mean totals for glacial erosion of 8 ± 8 m in Area 1 and 27 ± 11 m in Area 3. These estimates support previous views that glacial erosion depths and rates on shields can be low and that pre-glacial landforms can survive long periods of glaciation, including episodes of wet-based flow. [ABSTRACT FROM AUTHOR]

ABSTRACT The detailed clay varve chronology and an extensive knowledge of the highest postglacial shore level elevation (HS) in northern Sweden, along the Bothnian western coast, provides opportunities for determining the pattern of isostatic rise and centre of uplift from the early Holocene. The shore level of c. 10 100 cal yr bp (10 ka) for this area is determined by subtracting, from the metachronous HS elevations, the fall in relative sea level between local deglaciation time and the chosen reference time. The area of highest uplift since 10 ka is situated somewhat north of the location with the world-record HS ( Skuleberget in Ångermanland), but south of the area with most rapid current rise. Wave erosion marks in the studied area are seen to be more consistent indicators of HS than glaciofluvial delta levels. The gradients of shore marks at 10 ka are generally small within the investigation area. The regional 10 ka shore level pattern shows considerable irregularity compared to the current uplift. Central Sweden and western Finland show 10 ka gradients that indicate isostatic response to late (13-10 ka bp) glacial unloading. Indications of a secondary uplift centre west of the present investigation area are reported in previous work; this also suggests rapid isostatic response to unloading. Finally, the possibility of identifying errors in the varve-dated deglaciation chronology via the 10 ka shore level pattern is illustrated. [ABSTRACT FROM AUTHOR]

ABSTRACT The Pleistocene Cieśle succession accumulated in a subglacial tunnel and shows three sedimentological units: (1) trough cross-stratified sand with granules deposited in deep channels up to 5.4 m, (2) trough stratified and massive gravels deposited in a very deep channel up to 6.2 m eroded by a catastrophic hyperconcentrated flow, and (3) a massive diamicton, interpreted as a basal till of melt-out type. We focus on angular and deformed sandy clasts that occur in the second unit. It appears that thermal erosion, short transport in a sediment-laden current and sudden sedimentation were responsible for the oversized sandy clasts that occur in the gravel glaciofluvial deposits. The deposits are characterized by large-scale erosional scours, massive structure, and fluid-escape deformations. This combination of features can be used as a key tool for the interpretation of hyperconcentrated-flow conditions beneath Pleistocene ice sheets. [ABSTRACT FROM AUTHOR]

Climate change is challenging the notions of permanency and stability on which the ideal of the sovereign, territorial state historically has rested. Nowhere is this challenge more pressing than in the Arctic. As states expand their sovereignty claims northward in pursuit of potential opportunities (in many cases made possible by climate change), these same states are being confronted with the region's increasing territorial indeterminacy (which also is exacerbated by climate change). To investigate how climate change is challenging the territorial imaginaries around which notions of sovereignty historically have been based, we turn to three debates in the contemporary Arctic: the question of sovereignty in the Northwest Passage, conflicts over territorial control in the Arctic Ocean, and the potential for enhanced multilateral governance. Through our study of these debates we engage the Arctic both as a region that is undergoing climate change's most extreme impacts and as a laboratory for understanding how these and similar impacts might modify the spatial organization of political authority across the world. [ABSTRACT FROM AUTHOR]

Mountain geodynamics represent highly scale-dependent interactions involving climate, tectonic, and surface processes. The central Karakoram in Pakistan exhibit strong climate-tectonic feedbacks, although the detailed tectonic and topographic responses to climate perturbations need to be systematically explored. This study focuses on understanding climate variations in relation to glacier erosion and relief production. Field data, climate modeling, remote sensing, geomorphometry, geochronology, glaciology, and geomorphological assessment are utilized to characterize climate change and geomorphic response. Climate simulations suggest that the region has experienced significant climate change due to radiative forcing over at least the past million years due to changes in Earth's orbital configuration, as well as more temporally rapid climate dynamics related to the El Nino Southern Oscillation. Paleoclimate simulations support geomorphological evidence of multiple glaciations and long-term glacier retreat. Mesoscale relief patterns clearly depict erosion zones that are spatially coincident with high peaks and rapid exhumation. These patterns depict extreme spatial and temporal variability of the influence of glacier erosion in the topographic evolution of the region. Results support the interpretation of high-magnitude glacial erosion as a significant denudational agent in the exhumation of the central Karakoram. Consequently, a strong linkage is seen to occur between global, or at least hemispheric, climate change and the topographic evolution of the Karakoram and the western Himalaya. [ABSTRACT FROM AUTHOR]

In a gravel pit near Hultsfred, at the eastern margin of the South Swedish Upland, gravelly, sandy and silty-sandy beds covered by a thick, stratified gravelly diamicton are exposed. Large folds and shear-planes indicate post-depositional deformation of the sorted sediments, which according to OSL dating have a maximum Middle Weichselian (∼60 ka) age. The sand and gravel are interpreted as glaciofluvial sediments that were deposited laterally during a Middle Weichselian deglaciation, or possibly subglacially during the Late Weichselian. The large-scale deformation was due to glaciotectonics, caused by an overriding wet-based ice sheet during the last deglaciation. The subglacial hydrostatical pressure was high and led to the formation of downward-injected clastic dykes. A basal till, which forms the cover moraine in the area, caps the succession. The fairly frequent occurrence of sub-till sediments on the South Swedish Upland demonstrates the limited effect of glacial erosion in parts of this area. During the Last Glacial Maximum, the South Swedish Upland was an 'island' of slow-moving, polythermal and at least partly non-erosive ice, surrounded by faster ice-streams in the Baltic and in the Skagerrak. The ice sheet may have left its main impact on the landscape during short periods during advance and deglaciation only. [ABSTRACT FROM AUTHOR]

The classic U-shaped valley is a typical expression of glacial erosion, but situations can occur where the glacier effects little to no change in the landscape. Such an occurrence would be where the glacier is cold-based and remains so during its demise - never entering into a warm-based (erosional) phase. Here, two present-day examples are provided where glaciers exist, but the valley form has remained unaltered despite multiple glacial events. The key to such a situation is suggested to be the altitudinal/latitudinal spatial location, such that the ice has completely disappeared before, during the move towards an interglacial, there is time for it to transform into warm-based ice. The argument can then be made that perhaps the same is the situation for the reconstructed, small glaciers in the Lesotho-Drakensberg area. The ice was cold-based due to a combination of its thinness and the cooling effect of shading. Cold-based ice could explain the lack of striated clasts found in the moraines, the absence of any change to the valley form, and the preservation of breaks in the slope observed in the area of the former glacier. [ABSTRACT FROM AUTHOR]

The study is based on observations from the coastal zone near Åkvåg in Risør Municipality, Southern Norway. The aim of the article is to present and discuss spatial variations in the locations of potholes and channels over a large-scale roche moutonnee. Detailed descriptions and interpretations of features in the study area are presented. Glaciofluvial erosional forms display distinct concurrence of a NW-SE orientation, based on measurements of longitudinal axes. The great majority of documented glaciofluvial erosional forms are situated on large-scale roche mountonnee's lee side, facing south-east. [ABSTRACT FROM AUTHOR]

Glacial erosion patterns on northwest Iceland are quantified using a Geographic Information System (GIS) in order to interpret subglacial characteristics of part of northwest Iceland affected by ice sheet glaciation. Ice scour lake density is used as a proxy for glacial erosion. Erosion classes are interpreted from variations in the density of lake basins. Lake density was calculated using two different methods: the first is sensitive to the total number of lakes in a specific area, and the second is sensitive to total lake area in a specific area. Both of these methods result in a value for lake density, and the results for lake density calculated using the two methods are similar. Areas with the highest density of lakes are interpreted as areas with the most intense erosion with the exception of alpine regions. The highest density of lakes in the study area exceeds 8% and is located on upland plateaus where mean elevations range from 400 to 800 m a.s.l. Low lake density (0-2%) is observed in steep alpine areas where steep topography does not favor lake development. The GIS analysis is combined with geomorphic mapping to provide ground truth for the GIS interpretations and to locate paleo-ice flow indicators and landforms. The patterns identified in this study illustrate distinct regions of glacial erosion and flow paths that are best explained by two independent ice sheets covering northwest Iceland during the Last Glacial Maximum (LGMI. Areas of alpine glacial landforms and the presence of nunataks within the glaciated region support interpretations that ice-free regions or cold-based ice cover existed on parts of northwest Iceland during the LGM. The methods developed in this study are easily transferable to other formerly glaciated regions and provide tools to evaluate subglacial properties of former ice sheets. The data generated yield important subglacial boundary conditions for ice sheet models of Iceland. [ABSTRACT FROM AUTHOR]

Soils of the McMurdo Dry Valleys are among the most extreme terrestrial environments, hosting low-diversity food webs of microbes, protozoa, and metazoan invertebrates. Distribution of soil invertebrates, particularly nematodes, is related to the highly variable soil geochemistry of the valleys. Bull Pass is a glacially carved area within the McMurdo Dry Valleys where a broad range of geochemical conditions occurs along a continuous soil gradient. This site provides the opportunity to investigate how soil geochemistry controls nematode distribution on a local scale, and to establish correlations that may also be relevant at regional scales. At Bull Pass, two nematode species were present, with the dominant Scottnema lindsayae occurring in >30% of the samples. There were significant negative correlations between live nematode abundance and soil nitrate concentration and salinity, consistent with experiments showing strong salinity effects on nematode survival. A logistic regression model based on data sets from across the McMurdo Dry Valleys showed a strong negative relationship between soil salinity and the probability of live nematodes occurring. Soil chemistry and nematode distribution from the Bull Pass transect are compared with model results and suggest that the larger-scale distribution of nematodes across the McMurdo Dry Valleys may be reflected in the smaller-scale chemical and biological gradients at Bull Pass. [ABSTRACT FROM AUTHOR]

Glacial retreat on the Tibetan Plateau and surrounding regions is characteristic since the 1960s and has intensified in the past 10 yr. The magnitude of glacial retreat is relatively small in the interior of the Tibetan Plateau and increases to the margins of the plateau, with the greatest retreat around the edges. Glacial retreat in this region is impacting the hydrological processes in the Tibetan Plateau and surrounding regions. The glacial retreat has caused an increase of more than 5.5% in river runoff from the plateau. In some areas, such as the Tarim River basin, the increase in river runoff is greater. Glacial retreat has also caused rising lake levels in the areas with large coverage of glaciers, such as the Nam Co Lake and Selin Co Lake areas. Rising lake levels are devastating grasslands and villages near the lakes. [ABSTRACT FROM AUTHOR]

This paper discusses direct current resistivity soundings and geomorphological studies of Quaternary deposits in two glacial troughs in the Abisko Mountains of northern Sweden. The subject of the fieldwork is the depth of Pleistocene glacial erosion. Studies were carried out in 1998 and 2003 in the Kärkevagge and Vassivagge. The estimated thickness of Quaternary deposits and bedrock properties are discussed in the broader context of glacial erosion studies in the Abisko area. Geophysical and geomorphological studies suggest that the depth of glacial erosion was highly differentiated from –190 m in the Torneträsk basin to the metric overall erosion on the upland plateau. In medium-sized valleys several kilometres long, erosion depth measures 30–50 m. Present-day stream channel patterns reveal a strong relation to the bedrock configuration in valley floors [ABSTRACT FROM AUTHOR]

Twenty-six sites with remnants of gravelly saprolites (grus) have been located in southeast Sweden. Joint block hills (castle kopjes) and steep rock walls with weathered joints as well as rounded boulders are documented to have an origin in deep weathering and subsequent stripping of saprolites. The saprolite remnants and landforms result from the fragmentation of the re-exposed sub-Cambrian peneplain along fracture systems. Only shallow saprolites occur on the elevated intact parts of the sub-Cambrian peneplain, while saprolites up to 20 m thick are encountered in areas where the sub-Cambrian peneplain is fractured and dissected. Neogene uplift with reactivation of the weathering system is thought to be the main cause of saprolite formation. Deep weathering is thus judged to have been the major agent of landform formation in the study area, while glacial and glaciofluvial erosion has contributed mainly by stripping saprolites, detaching corestones, and plucking joint blocks along weathered joints. [ABSTRACT FROM AUTHOR]

The fundamentally geographic issue of the amounts and spatial patterns of erosion necessary to produce classic glacial landforms such as U-shaped valleys has been debated by scientists for over a century. Terrestrial cosmogenic nuclide (TCN) measurements in glacially abraded bedrock were used to determine patterns of glacial erosion and to quantify the amount of rock removed during the last glaciation along valley-side transects in Sinks Canyon, Wind River Range, Wyoming, and the South Yuba River, Sierra Nevada, California. Surface exposure ages from bedrock and erratic samples obtained during this study indicate last deglaciation between 13–18 ka in the South Yuba River and 15–17 ka in Sinks Canyon. These ages are in agreement with previously published glacial chronologies. In both areas, samples from valley cross sections revealed a pattern of erosion during the last glaciation that decreased toward the lateral limit of ice extent, as predicted by numerical models, while transects further upstream recorded >1.4 meters of bedrock removal throughout. The effects of varying interglacial erosion and surface exposure histories on modeled glacial erosion depths were tested, validating the methodology used. The results demonstrate that the TCN technique, applied at the valley scale, provides useful insight into the spatial pattern of glacial erosion. Extensive sampling in areas with limited erosional loss may provide detailed records of erosion patterns with which to test predictions generated by models of ice dynamics and erosion processes. [ABSTRACT FROM AUTHOR]

Glacial deposits are identified from within and near Sinks Canyon, southwest of Lander, Wyoming, representing 6 first-order Pleistocene glaciations. Relative-age analyses of the deposits (including moraine morphology and soil development characteristics) indicate that they correspond to 4 glaciations previously identified from the Wind River Range (Pinedale, Early Wisconsin, Bull Lake, and Sacagawea Ridge) and to 2 older glacial events (Younger and Older Pre-Sacagawea Ridge). 10Be and 26Al exposure ages associated with recessional Pinedale deposits are similar to those associated with recessional Pinedale deposits elsewhere in the range. 10Be and 26A1 exposure ages also support the identification of Early Wisconsin deposits here. The Early Wisconsin deposits represent the second locality where O-isotope stage 4 glacial deposits are described from the Wind River Range. Preliminary analysis of 10Be exposure data from the Older Pre-Sacagawea Ridge deposit suggests that a glacial advance occurred here before O-isotope stage 18 (> 800 ka). If true, then Sinks Canyon contains the most complete record to date of glaciation in the Wind River Range and the only reported record of Pleistocene glaciation prior to O-isotope stage 18 in the Rocky Mountains. [ABSTRACT FROM AUTHOR]

Subglacial eruptions in Vatnajökull have accounted for several jökulhlaups (glacial outburst floods) in the Northern Volcanic Zone (NVZ). These events and aeolian processes have had a considerable impact on the landscape evolution of the area. Most of this area is occupied by barren land cover; the northern margin of the barren land cover is advancing northwards, burying vegetation under wind-blown sediment. This paper presents a land-cover classification based on a supervised Landsat TM image classification with pre-processing and extensive field observations. Four land cover categories were identified: (a) lava cover (34.8%); (b) barren sediment cover (39.0%); (c) vegetation (25.1%); and (d) water and snow (1.1%). The mapping of sand transport routes denlonstrates that a major aeolian sand transportation pathway is situated in the western part of the study area. The sedimentary formation elongated towards the northeast is evidence of active and continuous aeolian sand transportation towards the north. Interpretation of the satellite image suggests that four main areas are affected by jökulhlaups along the Jökulsá á Fjöllum: Åsbyrgi, Grímsstaōir, Herōubrei&omacrl-Möōrudalur, and the Dyngjujökull sandur. In addition, jökulhlaup-related sediment cover (8%) in the study area, together with erosional features, are evidence of a severe and extensive jökulhlaup induced process of land degradation. Key words: jökulhlaups; land degradation; Iceland; remote sensing. [ABSTRACT FROM AUTHOR]

The undulating high plateaus of southern Norway, referred to as the Palaeic relief, are clearly distinct from the deeply incised valleys. The Palaeic relief has been regarded as either one or several surfaces, originating from differential weathering and pedimentation in warm climates or developed by fluvial cycles in response to changed base levels. Four major levels have recently been identified from a summit envelope surface. High-resolution elevation data from the Kjølen Mountains area, characterized by limited glacial erosion, were analysed to describe the relief. A surface/slope map showed three distinct surfaces with low inclination separated by slopes steeper than 6.5°. The stepped surfaces cut across different rock types. Their regular appearance in height along the main valleys, Gudbrandsdalen and Vågå-Otta valley, suggests a fluvial origin in response to successive uplift events. The main valleys are incised 300-600 m below the lowest Palaeic surface. Wide V-shaped tributary valleys, and valley benches preserved in resistant bedrock in Gudbrandsdalen, are indicative of fluvial incision, which can be correlated with Neogene uplift. A wide V-shaped valley was used as reference for estimation of the glacial erosion. A glacial deepening of the main valleys of 100-300 m and a widening of up to 1500 m was calculated. [ABSTRACT FROM AUTHOR]

Presents an assessment of the rates of subglacial erosion underneath the Fennoscandian ice sheet. Application of cosmogenic nuclide data to the assessment; Level and pattern of modification that resulted from the last glaciation; Glacial erosion estimates in the sites.

The Aurivaara Plateau in northern Sweden (68°N) displays apparently contrasting geomorphic patterns: on the one hand, wide-spread glacial deposits suggesting the complete overriding of the area by the Scandinavian ice sheet; on the other, well-preserved fragile tors and related spalling rounded corestones similar to those found in non-glaciated areas like Dartmoor. The association of preglacial weathering residuals and allochthonous deposits belonging to several Quaternary glaciations are attributed to a dominantly cold-based glacial regime. Field investigations and laboratory analyses of morainic material associated with 15 tor-like features scattered on the plateau suggest that till material and erratic blocks were repeatedly dropped during deglaciation stages deep into the tor joints and within associated blockfields without the glacial periods having had any significant erosional impact. The overall conservative glacial system of this upland area strongly contrasts with the high geomorphic impact of glacial erosion in the nearby lowland area, where Quaternary glaciations resulted in the 190 m overdeepening of the Torneträsk basin. The Aurivaara case study therefore supports both the glacial palimpsest theory developed in Scandinavia and the selective erosion model established in Scotland and North America. [ABSTRACT FROM AUTHOR]

Describes large roches moutonnees in Scotland and assesses their significance for studies of the processes of glacial erosion. Characteristics of sheet structures; Processes of glacial erosion; Lee-side block removal by glacial quarrying.

Evidence for glacial erosion of competent intrusive igneous rock is described for sites at Quart Pot Creek, Stanthorpe, Queensland. The bedrock, comprising the Stanthorpe Adamellite, was emplaced during the Early–Middle Triassic. It is argued that the pluton was exposed during the late Middle – Late Triassic and subjected to glacial erosion at that time. This was consequent to the rapid uplift and denudation of the landscape, which accompanied the Hunter–Bowen Orogeny. Burial of the eroded surface occurred most probably during that ice age and a subsequent period of subsidence. The ancient surface has been exhumed during more recent denudation. It is suggested that during the late Middle – Late Triassic, climatic conditions remained cold enough over this part of southeastern Australia at least for valley glaciers to form and influence landscape development. [ABSTRACT FROM AUTHOR]

ABSTRACT. Exploratory analysis of the orientation of 303 cryoplanation terraces in interior and western Alaska lends tentative support to the hypothesis that these landforms develop through localized erosion related to spatial patterns of snow accumulation and ablation. Cryoplanation terraces exhibit orientation patterns similar to those of cirques in several regions of Alaska. In climatically continental east-central Alaska, cryoplanation terraces are developed preferentially on north-facing slopes and the frequency distribution of terrace orientation is similar to but less concentrated than that of glacial cirques. In south-central Alaska, both cirques and terraces have bimodal frequency distributions corresponding to generalized wind patterns that predominated during Pleistocene glaciations. In western Alaska, terraces and cirques have relatively diffuse patterns without preferred orientation. No clear relation is apparent between the orientation of cryoplanation terraces and their size or elevation, although this may be an artifact of the current inability to differentiate terraces by age. Data from the Eagle Summit/Mastodon Dome area in interior Alaska indicate a possible relation between snowline elevation and the concentration of terrace orientation. [ABSTRACT FROM AUTHOR]

This study assesses the effects of glaciation on a drift-buried cuesta in southeast Michigan through analysis of detailed data for the underlying bedrock surface. Four separate areas of the cuesta affected differently by glaciation are examined. These illustrate (1) proximal lowering through abrasion, (2) lateral smoothing and trimming, (3) distal plucking and (4) pro- tection resulting from local structural-topographic relationships. It is shown that glacial effects on the cuesta vary in a meaningful way with changes in relationships between bedrock structure, lithology, surface configuration, and the direction of ice movement. [ABSTRACT FROM AUTHOR]

It is probable that spatial variability of topographic slope is best explained by some measure of the vertical topographic dimension in areas where insufficient time has elapsed since deposition of materials for slopes to attain time independence. A statistical analysis of some spatial relationships of mean topographic slope beyond that with local relief was conducted on erosional terrain in the glaciated Upper Mississippi Valley. Although all variables are statistically significant, the results indicate that factors other than relief, including nature of long stream profile, position orientation, degree of dissection, and parent materials, have less relevance in explaining place-to-place variation of topographic slope.

Glacial diversion of drainage has been a factor of first importance in determining the existing pattern of stream courses in regions occupied by Pleistocene continental glaciers. Aside from the well-known, large scale changes resulting from deposit of drift, transection of monor and major water partings by overflows from glacierpond waters was an important item in the reordering of stream courses. The efficacy of this type of erosion does not seem to have been fully appreciated. Deep gorges were evidently eroded with great rapidity by such overflow streams. In some places the cuts thus made served of themselves to confirm postglacial drainage in new channels. Elsewhere glacial erosion modified and commonly greatly enlarge the water-cut overflow channels. There is a marked tendency to compel the glacially reconstructed drainage to arcuate courses which reflect the outline of the normal lobate margins of the ice front. [ABSTRACT FROM AUTHOR]

This is a comment on: Hall, K., 2010. The shape of glacial valleys and implications for southern African glaciation. South African Geographical Journal, 92, 35–44. [ABSTRACT FROM AUTHOR]

New measurements of Watson River sediment and solute concentrations and an extended river discharge record improved by acoustic Doppler current profiler (ADCP) measurements are used to calculate the total sediment and solute transport from a large ice-sheet sector in southern west Greenland. For the 2006-2016 period, the mean annual sediment and solute transport was 17.5 ± 7.2 × 106 t and 85 ± 30 × 103 t, respectively (standard deviation given). The highest annual transport occurred in 2010, attaining values of 29.6 × 106 t and 138 × 103 t, respectively. The corresponding annual average values of specific transport are 1.39 × 103 t km−2 a−1 for sediment and 6.7 t km−2 a−1 for solutes from the approximately 12,600 km2 (95% ice covered) catchment, yielding an area-average erosion rate of 0.5 mm a−1. The specific transport is likely several times higher under the ice sheet near the margin where all meltwater passes than it is in the interior where the ice sheet is frozen to the bed. We conclude that the Greenland Ice Sheet is a large supplier of sediment and solutes to the surrounding fjords and seas. We find that the proglacial area can be a net source of sediments during high floods and we confirm that an increased amount of meltwater-transported sediments can explain the expansion of deltas around Greenland, contradictory to delta erosion observed elsewhere in the Arctic in recent years. [ABSTRACT FROM AUTHOR]

Reports that while the Swiss are ahead of the rest of the world in combating climate change, its glaciers are melting at a rapid pace. Efforts of Andermatt Gotthard Sportbahnen, a company that operates cable cars for the Andermatt ski resort, to remedy the impacts of glacial melting by covering parts of glaciers with lightweight, reflective foil blankets; Scrutiny of the strategy.

Reports that the first comprehensive study of glaciers on the Antarctic Peninsula revealed that 87 percent of 244 marine glaciers retreated in the 50 years prior to 2005. Details of research by the British Antarctic Survey and the U.S. Geological Survey; Implications of the survey's results.

Landforms are used as analytical tools to separate inherited features from the glacial impact on Precambrian basement rocks in southwest Sweden. The study covers three different palaeosurfaces, the sub-Cambrian peneplain (relative relief (r.r.) 0–20 m) with the character of a pediplain, an uplifted and dissected part of the sub-Cambrian peneplain (r.r. 5–40 m) and an etch-surface (r.r. 20–135 m), presumably sub-Mesozoic. The surfaces were recently re-exposed, probably due to a Neogene upheaval with some pre-glacial reshaping. Strong structural control and no alignment with glacial erosional directions other than those coinciding with structures, are arguments for etch processes as a most important agent for relief differentiation. This is strengthened by the occurrence of saprolite residues and etchforms in protected positions. The glacial reshaping of the sub-Cambrian flat bedrock surfaces is negligible. The glacial impact becomes more evident in the uplifted and dissected parts of the peneplain and within the hilly sub-Mesozoic surface. The higher the initial relief the more effect of glacial erosion on individual hills, both on the abrading side, with formation of roches moutonnées, and on the plucking side. Detailed etchforms are preserved in protected positions in spite of erosion by a clearly wet-based ice. The magnitude of the Pleistocene glacial erosion is considerably less than the amplitude of the palaeorelief in the entire area. Landscapes of areal glacial scouring have been described as comprising irregular depressions with intervening bosses scraped by ice and labelled ‘knock and lochan’ topography, but we suggest that an etched bedrock surface is a prerequisite for this type of landscape to develop. [ABSTRACT FROM AUTHOR]