Outwash Research Articles

Proglacial sediments in High Arctic glacier foreland: A case study of Werenskioldbreen, Svalbard

The glacier environment exhibits a high sensitivity to global climate change, leading to progressive deglaciation and the exposure of previously ice-covered land. The newly exposed terrain provides a valuable opportunity to observe rapid ecosystem changes, such as the accumulation of glacial sediments, the development of soil-forming and progressive alterations in water and biogeochemical cycles. While developing hydrological and hydrogeological models for the Werenskioldbreen proglacial expanding zone, we encountered a significant problem due to insufficient data for parameterizing glacial sediments, which constitute the environment for water flow and storage. This study provides detailed insight into the physicochemical parameters of glacial sediments and classifies them in terms of grain size distribution, hydraulic conductivity, pH and the content of carbon (Corg), nitrogen (Nt) and phosphorus (Pt). We found that the marginal outwash plains of Werenskioldbreen are characterised by gravelly sand, sandy gravel and silty sand (28.6%, 23.8% and 19% of the total sample contents, respectively). The lateral moraine contains sandy clayey silt, silty sandy gravel or sandy gravelly silt (7.1%, 4.8% and 2.4 % of the total sample contents, respectively). The chemical parameters of young glaciofluvial sediments have lower values than those of moraines. Corg ranged from 0.07% to 2.70%. Nt was < 1.00 g kg−1 for 95% of the samples and < 0.5 g kg−1 for 81% of them. Pt was between 0.48 and 1.18 g kg−1. In line with the studies on this subject already published, we confirm that there is clear a relationship between the type of geomorphological form, its age, and the physicochemical parameters of glacial sediments.

Passage and removal of the Amundsen Gulf Ice Stream, NW Laurentide Ice Sheet, recorded by the glacial and sea level history of southern Banks Island, Arctic Canada

Earlier reconstructions of the glacial history of the western Canadian Arctic Archipelago, commonly portrayed Banks Island as an ice-free biological refugium during the Last Glacial Maximum, ostensibly constituting the northeast extremity of Beringia. This has now been contradicted by widespread fieldwork across the northern and western coasts documenting their inundation by the northwest Laurentide Ice Sheet that extended onto the polar continental shelf. Here we report the surficial geology and deglacial sea levels across southern Banks Island completing the island-wide evidence for a pervasive ice cover during the Late Wisconsinan.Moraines and erratics confirm the passage of an ice stream at least 1.1 km thick through Amundsen Gulf that onlapped the south coast of the island. The inland margin of the ice stream is marked by a prominent 80 km long shear moraine (Sachs moraine) that contacted thin, cold-based Laurentide ice crossing the island's interior. Subsequent thinning and retreat of the Amundsen Gulf Ice Stream from the Sachs moraine occurred in concert with its separation from topographically-confined ice lobes in the interior recorded by prominent ice-marginal meltwater channels. As the ice stream retreated offshore, a prominent kettled outwash plain was deposited along the coast marking marine limit at 20 m asl. From an unknown position offshore, the ice stream readvanced deforming the south shore of the kettled lowland marked by the 40 km long ‘Sand Hills moraine’. Based on updated field mapping, the 'Sand Hills moraine' is now recognized as the westward extension of the more widespread Jesse moraine belt.Deglacial marine limit rises eastward across the island from 11 to 40 m asl, bordering Prince of Wales Strait. Marine limit and all lower shorelines across the island's south coast (for ∼ 200 km) are barren of marine shells. This is because sea level had regressed from marine limit to a lowstand offshore before Pacific molluscs recolonized the western Canadian Arctic at 13.7 cal ka BP, their entry occasioned by the resubmergence of Bering Strait. This requires that the breakup of the western Amundsen Gulf Ice Stream (including the M'Clure Strait Ice Stream along northern Banks Island) occurred before 14 cal ka BP, documenting that the NW Laurentide Ice Sheet must have contributed to Meltwater-Pulse-1A. Although the retreat from the outermost parts of the Jesse moraine belt also pre-date the arrival of shells, we show that the youngest (central) segment along eastern Amundsen Gulf dates to ∼12.9 cal ka BP, documenting that the Jesse moraine belt is highly time transgressive (spanning >13.7 to 12.9 cal ka BP). Radiocarbon dates on woody plants and bryophytes demonstrate that the island was biologically viable as early as 12.6 cal ka BP and that all coastlines were submergent soon afterwards and remain so today.

Distribution of Woody Biomass on the Outwash Plain of a Retreating Glacier in Southern Iceland: Role of Microhabitat and Substrate

The Skaftafellsjökull is an outlet glacier in southern Iceland that has been retreating since 1890. While multiple studies have examined primary succession on the foreland of this glacier, no study has examined the distribution of woody biomass on the outwash plain. We investigated the distribution of one species, Betula pubescens, that grows on the foreland moraines and outwash plain of this glacier. The topography of the outwash plain is heterogeneous, consisting of broad bars of outwash gravel and boulders that are separated by narrow incised channels and broader swales. Vegetation on the outwash plain is primarily a moss–heath community. Birch are sparse on the outwash bar tops, but are more abundant and larger in the channels and swales between the bars. Although the area of the channels on the outwash plain is much less than that of the bar surfaces, the woody biomass of the outwash plain is dominated by the birch within these channels. Consequently, the mean woody biomass of the outwash plain exceeds that of the moraines. We propose that the microhabitat of the outwash plain channels provides a favorable environment for the growth of birch, primarily by providing a fine-grained substrate that promotes successful seeding and growth.

The Temporal and Spatial Dynamics of Succession in a Glacial Foreland in Southern Iceland: The Effects of Landscape Heterogeneity

One of the more visible consequences of anthropogenic climate change is the ongoing retreat of glaciers worldwide. Rates of primary succession in the resulting glacial forelands are commonly calculated from a single measurement set using a single set of measurements across a landscape of varying age, but repeated measurements over decadal scales may be a more effective means of examining the rates and trends of colonization and community development. Repeated measurements of vegetation groups in a glacial foreland in southern Iceland demonstrate that successional changes are measurable, as shown by the calculation of the dissimilarity index at sites over a 15 year interval. Inter-site dissimilarity validates the essential paradigm of primary succession, where vegetative coverage increases in the glacial foreland as a function of time and supports earlier interpretations saying that species richness decreases on older surfaces, even as the total vegetation cover increases. However, successional processes are subject to major abiotic factors, such as aspect, which is controlled by landscape topography, and the substrate composition. The glacial moraines and outwash plain are underlain by different substrates which produce separate successional trajectories. Succession on the moraines ultimately produces a birch-shrub-heath community, while the outwash deposits promote development of a moss-heath community.

Microbial dynamics in rapidly transforming Arctic proglacial landscapes

Arctic glacial environments are rapidly changing, as the Arctic warms at a rate three to four times faster than the global average (the phenomenon known as Arctic amplification). Microorganisms are uniquely adapted to extreme glacial environments and studying how ecological and climatic feedback loops affect the diversity of these communities is crucial to the characterisation of vulnerable Arctic habitats. Glacial landscapes span a wide range of habitats, from glacier ice to marine waters, and encompass terrestrial, aquatic, and interzonal systems. While glacier shrinkage has been the focus of scientific attention, auxiliary habitats are also impacted by rapid glacier retreat. Auxiliary habitats include terrestrial systems, such as outwash plains, vegetated periglacial environments, and aquatic systems, such as glacier-fed streams, lakes, and glacier-adjacent marine environments. Glacier recession drives high-impact changes in glacier-associated habitats: rising temperatures, increased light penetration of glacial streams, changes in nitrogen-to-phosphate ratios, and increases in availability of glacier-derived organic compounds. In turn, microbial systems in these habitats may experience changes in nutrient dynamics and shifts in community structures. The exposure of new lands by retreating glaciers may also result in increased dust and microbial dispersal into the atmosphere. Here, we discuss the effects of climate change on glacial microbiomes and the feedback loops between microbial community dynamics and the large-scale climatic processes in the Arctic. We characterise aspects of vulnerable microbial ecosystems and highlight the importance of preserving unseen microbial biodiversity. We then outline current capacities for microbial conservation, focusing on cryopreservation and biobanking. Lastly, we suggest future research directions and steps that academic and governmental institutions may take to foster research and collaboration with Indigenous communities.

High seed losses in mountain birch (Betula pubescens ssp. tortuosa) and developmental, ecological, and environmental correlates

Abstract Plants typically experience great losses from their reproductive potential represented by ovule production to the post-dispersal crop of viable seed. We examined seed density and viability in a founder population of mountain birch (Betula pubescens ssp. tortuosa), aiming to quantify losses at different stages and examine potential selection forces on the reproduction success of the founder generation of an isolated population. At the time of the study (2017–2020), the population had recently reached reproductive maturity, following its colonization around 1990 through long-distance dispersal onto an early successional outwash plain in southeast Iceland. Seed densities were high, but 89% of apparently intact seeds did not contain an embryo, despite being visually indistinguishable from filled seeds. Externally evident losses amounted to about 45% of the total seed crop and were mostly due to predation by the gall midge Semudobia betulae. When all losses were accounted for, 2.7% of the seed crop remained viable and germinated. Pollen limitation may partially explain the high incidence of empty seeds. Excessive flower production is compatible with the predator satiation hypothesis but cannot explain pre-dispersal losses. Another adaptation to predation, masting, appears poorly developed in Iceland. Our results suggest the presence of constraints on the reproduction potential of the new island population, that are more limiting than in neighbouring populations, and we discuss their developmental, ecological, and environmental correlates.

Feasibility of constructed soils for tree planting – A pilot study in New York City

Constructed soils are soils that are created with a mixture of various materials. An innovative soil exchange program - the Clean Soil Bank (CSB) in New York City allows recycling of clean glacial outwash sediments excavated from depth at construction sites. One previous study showed that soils constructed from CSB sediment and compost can effectively support crop growth in community gardens, but no research has been conducted on its potential usage as a medium for tree growth. Moreover, biochar has been used to improve soil quality, but its efficacy for street trees incorporated into constructed soils has largely not been quantified in the field. The objective of this project was to evaluate the feasibility of using soils constructed from the CSB and compost for tree planting and to investigate the impact of biochar on tree performance. Thirty-six trees of two species (Maackia amurensis and Zelkova serrata) were planted in 2019, on the sidewalks of a residential-business neighborhood in Bronx, New York. Each tree pit contains one of three soil types: type A - existing and purchased topsoil mixed with 33% compost and biochar, type B - CSB sediment mixed with 33% compost, and type C - CSB sediment mixed with 33% compost and biochar. Soil samples were collected in 2019 (before planting) and in 2021. Tree health assessments were conducted in September 2020 and July 2021 using a protocol developed by the USDA Forest Service. Other tree health parameters collected include diameter at breast height (DBH), crown diameter, tree height, photosynthetic capacity, and foliar chemistry. Significant differences in bulk density, water holding capacity, and K, Fe, and Zn concentrations were found among the three soil types. However, comparison of tree performance and foliar chemistry showed no systematic differences among the three soil types. The results indicate that CSB sediment mixed with compost can be an effective replacement for purchased topsoil for tree growth. No evidence was found that biochar provides additional benefits to street tree performance. Considering the abundant availability of glacial outwash sediment at low cost to the city, as well as access to locally produced compost, constructed soils can be a reliable source of material for urban forestry programs.

Wartanian glacial sediments: insights into deglaciation of Polish Lowlands and Highlands border for geotourism

Abstract This paper presents five sites located in the marginal zone of the Wartanian stadial within the Odranian Glaciation (MIS6a) on the border of the Central Polish Uplands and Lowlands, representing different glacial forms and geological structures: terminal moraine hill, undulating moraine hill, sedimentary margin of the ice sheet, kame hill, and outwash plain. This differentiation is also reflected in the petrographic composition of the gravels and the interesting surface microstructures of the Scandinavian erratic boulders. This small study area, with its high geodiversity, which we have identified and investigated, has considerable potential for sustainable development. Geotourism is a tool for this development in a peripheral tourist region, providing both economic benefits for the local population and conservation services for the geoecosystem.

Comparative Spatial Modeling of Bretziella fagacearum Distribution in Northern Wisconsin, United States.

Bretziella fagacearum, the ascomycete fungus oak wilt, is considered a virulent threat to North American oaks, but the influence of the physical environment on this pathosystem remains unclear, particularly at the forest scale. This study explored the influence of terrain and soil factors on B. fagacearum infections, applying discrete and continuous spatial models to investigate the question, besides proximity to other infections, which environmental factors influenced B. fagacearum incidence? Locations of infections were recorded from 586 confirmed B. fagacearum sites, identified from 2004 through 2021 in a 76 km2 area of deep, sandy glacial outwash in Chequamegon-Nicolet National Forest, northern Wisconsin. Public datasets derived from remote sensing were incorporated as covariates, describing terrain elevation (USGS 10-m DEM), soil physical and chemical properties (POLARIS), and forest composition (WiscLand2). Spatial models included generalized additive models (GAMs) and Neyman-Scott cluster process models. The results indicated that spatial dependence and the distribution of oak forests were the most important drivers of B. fagacearum distribution in this area, with more minor influence from elevation, hill shade, and drainage patterns. Comparison between modeling approaches indicated that-at this scale and in this area-the most accurate models were those that included host distribution, spatial dependence, and quantitative terrain and soil descriptions. However, a close approximation could be attained using nonlinear models (GAMs) that incorporated only host distribution and spatial dependence.

Loess chronology and composition as interpreted through the lens of fossiliferous lake sediments in central Illinois, USA

Silty lacustrine and paludal records spanning from the penultimate deglaciation (late Illinois Episode) to the present are preserved in kettles formed during marine isotope stage (MIS) 6 that lie adjacent to the MIS 2 Manito terrace along the valleys of the Sangamon and Illinois Rivers. Geochemical, mineralogical, particle-size, and chronological records from two basins, Smith Lake and Lake Ben, provide a unique opportunity to assess loess age and provenance of the south-central Laurentide ice sheet. Here, I focused on deposits of redeposited loess of the last glaciation (Wisconsin Episode). Other than subtle laminations and fossils of emergent and aquatic plants and animals, the silty texture, chemical composition, and mineralogy of the lake sediment closely resemble Peoria Silt (loess). Sediment-core records sampled from Smith Lake and Lake Ben in Mason County, Illinois, confirm rapid deposition of proximal loess derived from the nearby outwash plain of the Illinois River from ca. 30.9−18.0 calibrated (cal) k.y. B.P. From 18.0−14.7 cal k.y. B.P., deposition of proximal loess was gradually replaced by far-traveled (distal) loess chiefly derived from Superior lobe provenance and global dust. The succession is capped by a cumulic gleysol that was truncated by recent plowing. Proximal loess deposits in lakes Smith and Ben are composed primarily of very fine sand, coarse silt, and medium silt (125−16 µm) compared to the distal facies (fine silt and finer sediment: <16 µm). Proximal loess that originated from outwash of the Lake Michigan lobe contains abundant Ca, Zr, Sr, illite, and magnetic minerals. The distal facies contains relatively abundant Rb, Al, K, Si, Cu, and Pb, and it is enriched in smectite (relative to illite) and depleted in magnetic minerals. Radiocarbon ages on terrestrial gastropod aragonite in loess from the nearby New Cottonwood School and Thomas Quarry sites indicate that Peoria Silt deposition ended between 18 cal k.y. B.P. and 16 cal k.y. B.P. At these localities, the upper part of the record is complicated by the modern soil, which has altered soil organic matter and leached carbonate. At Lake Ben, the radiocarbon record of emergent aquatic vegetation indicates that sediment accumulation rates and the ratio of proximal to distal loess decreased at the correlative interval that yielded the youngest snail shell ages at Cottonwood School. The upward increase in element concentrations such as Al and decrease in coarse/fine silt ratios in the modern soil are prominent features in the Lake Ben record dating from 18−14 cal k.y. B.P. This correlation strongly suggests that many of the features of the modern soil were not developed into uniform parent material but, rather, were inherited from incremental addition of distal loess to proximal loess, collectively identified as Peoria Silt. The paucity of key elements (Cd, Hg, Se, Ag, Au) in this transition zone suggests limited contributions from western lobes (i.e., Des Moines and James lobes), but abundant Ti and Cu suggest a contribution from the Superior lobe. A new wrinkle in this interpretation is that the rise in elements such as Al, Rb, and Si suggests significant additions from generic dust from unknown sources.

Current and future roles of meltwater–groundwater dynamics in a proglacial Alpine outwash plain

Abstract. Glacierized alpine catchments are rapidly evolving due to glacier retreat and consequent geomorphological and ecological changes. As more terrain becomes ice-free, reworking of exposed terrain by the river as well as thawing of the top layer may lead to an increase in surface and subsurface water exchanges, leading to potential changes in water storage and release, which in turn may impact ecological, geomorphological and hydrological processes. In this study, we aim to understand the current and future hydrological functioning of a typical outwash plain in a Swiss Alpine catchment. As with many other fluvial aquifers in alpine environments, this outwash plain is located at the valley bottom, where catchment-wide water and sediment fluxes tend to gather from multiple sources, may store water and provide specific habitats for alpine ecosystems. Their dynamics are however rarely studied in post Little Ice Age proglacial zones. Based on geophysical investigations as well as year-round stream and groundwater observations, we developed a simplified physically based 3D MODFLOW model and performed an optimized automatic calibration using PEST HP. We highlight the strong interactions between the upstream river and the aquifer, with stream infiltration being the dominant process of recharge. Groundwater exfiltration occurs in the lower half of the outwash plain, balancing out the amount of river infiltration at a daily timescale. We show that hillslope contributions from rain and snowmelt have little impact on groundwater levels. We also show that the outwash plain acts as a bedrock-dammed aquifer and can maintain groundwater levels close to the surface during dry periods lasting months, even in the absence of glacier meltwater, but may in turn provide only limited baseflow to the stream. Finally, we explore how new outwash plains may form in the future in this catchment due to glacier recession and discuss from a hydrological perspective which cascading impacts the presence of multiple outwash plains may have. For this case study, we estimate the total dynamic storage of future outwash plains to be about 20 mm, and we demonstrate their limited capacity to provide more stream water than that which they infiltrate upstream, except for very low river flows (<150 to 200 L s−1). Below this limit, they can provide limited baseflow on timescales of weeks, thus maintaining moisture conditions that may be beneficial for proglacial ecosystems. Their role in attenuating floods also appears limited, as less than 0.5 m3 s−1 of river water can be infiltrated. The studied outwash plain appears therefore to play an important role for alpine ecosystems but has a marginal hydrological effect on downstream river discharge.

Early onset of aridity in the past millennium: Insights from vegetation dynamics and climate change in the alpine, cold-desert region of Trans Himalaya, India.

Palynological analysis of surface soil and sub-surface sediments from the outwash plain of Hamtah Glacier, Lahaul-Spiti, India, has brought out the vegetation and climatic changes in the area during the last 1580 years. The arboreal and non-arboreal pollen ratio (AP/NAP) has been used to demarcate the different vegetation and climatic zones, complemented by the frequencies of the broad-leaved taxa. Lower values of thermophilous, broad-leaved arboreal taxa, indicate that the region experienced cold-arid conditions between 1580 and 1330 yr BP (AD 370-620); which can be related to the Dark Ages Cold Period (DACP). Thereafter, between 1330 and 950 yr BP (AD 620-1000), a rejuvenation of the broad-leaved elements reflects the initiation of a comparatively warm and moist phase, marking the Medieval Climatic Anomaly (MCA) in the region. The warm-moist phase was, however, short-lived, and from 950 yr BP to the Present (AD 1000 onwards), the region saw a return to cold-arid conditions, as evidenced by a sharp fall in the AP/NAP ratio. This cold-arid phase was, nevertheless, punctuated by a warm-moist period during 790 to 680 yr BP (AD 1160-1270), which marks the terminal phase of the MCA. After the termination of the MCA, the Little Ice Age (LIA) is well-marked in the area. The culmination of the long cold-arid regime is characterized by warmer conditions over the last 160 years, which is the manifestation of the Current Warm Period (CWP). Magnetic susceptibility (χlf) and sediment geochemistry (Weathering Index of Parker) were also attempted to have a multi-proxy approach, and show a general compatibility with the palynological data. The palaeoclimatic evidences suggest shorter warm periods and extended colder phases during the last 1580 years; in this high-altitude, cold-desert, Trans Himalayan region.

Predicting Foliar Nutrient Concentrations across Geologic Materials and Tree Genera in the Northeastern United States Using Spectral Reflectance and Partial Least Squares Regression Models

Spectral data can potentially offer a rapid assessment of nutrients in leaves and reveal information about the geologic history of the soil. This study evaluated the capability of the partial least squares regression (PLSR) for estimating foliar macro- and micronutrients (Ca, Mg, K, P, Mn, and Zn) using spectral data (400 to 2,450 nm). First, filter-based wavelength selection was conducted to reduce the independent variables. PLSR performance was then assessed across 4 geologic materials (coarse glacial till, glaciofluvial, melt-out till, and outwash) and 4 dominant tree genera ( Acer , Betula , Fagus , and Quercus ) in the northeastern United States. The spectral ranges 400 to 500 nm and 1,800 to 2,450 nm were found to be the most important spectral regions for estimating foliar nutrient concentrations. The developed PLSR model predicted 6 foliar nutrients with moderate to high accuracy (adjusted R 2 from 0.60 to 0.75). Foliar macronutrient concentrations were estimated with higher accuracy (mean adj. R 2 = 0.69) than micronutrient concentrations (mean adj. R 2 = 0.635). The prediction for the individual tree genera group and the individual geologic materials group outperformed the combined group; for instance, the adj. R 2 for estimating Ca and P was 39% higher for American beech ( Fagus grandifolia ) than all tree genera combined. Spectral measurements combined with wavelength selection and PLSR models can potentially be used to quantify foliar macro- and micronutrients at regional scales, and taking into account geologic materials and tree genera will improve this prediction.

Back-analysis of the paraglacial slope failure at Grewingk Glacier and Lake, Alaska

The relationship between rock-slope failure and glacier retreat is complex, and paraglacial failures often lack clearly identified triggers. To better understand the role of glacier retreat in rock-slope failures, we analysed the processes that led to the October 1967 Grewingk landslide in Kachemak Bay State Park on the Kenai Peninsula, Southcentral Alaska. The rock material collapsed onto the glacier toe and into its pro-glacial lake and produced a tsunami wave that swept the outwash plain. On the day of the failure, rainfall and snowmelt were well within normal ranges, and seismic records show no significant shaking. Three years prior to the 1967 failure, the slope withstood the second largest earthquake ever recorded (Great Alaskan earthquake, MW 9.2). We reassessed the volume of the failure by differencing pre- and post-digital terrain models and found a value of 20–24 × 106 m3, which is four times smaller than a previous estimate. The back analysis of the Grewingk landslide is based on remote sensing data and field measurements including aerial satellite image analysis, detailed surveying and understanding of the structural geology, a kinematic analysis, and runout modelling. Our research provides an example of a major paraglacial failure that lacks an obvious trigger and points to several geological factors and changing environmental conditions that likely promote such failures. This study further indicates that the Grewingk landslide, pre-conditioned by the geometry of faults and joints, may have reached a critical stability state due to internal processes and the potential combined effects of seismic activity and glacier retreat prior to the collapse.

Albedo on a glacial foreland at ground level and landscape scale driven by vegetation-substrate patterns

Recent anthropogenic climate change has caused both glacial retreat and increased vegetative growth on Arctic and subarctic tundra landscapes resulting in changing albedo and energy budgets. Glacial forelands are topographically and ecologically heterogeneous landscapes comprising ice-contact and outwash deposits subject to primary succession. The most recent moraines on the foreland of the Skaftafellsjökull in southern Iceland are mostly unvegetated, but vegetation cover increases with the age in a general sense. Vegetated outwash channel terraces occur between the moraines, and a broad vegetated outwash plain occurs distal to the oldest moraine. Variations in albedo were measured at ground level to determine the specific role of vegetation types and varying substrates. Albedo and coverage by major plant groups were measured along transects established on moraines ranging in age from 20 to 130 years and the terrace of one outwash channel and three locations on the outwash plain. Total vegetation cover and coverage by mosses increases on the glacial moraines largely as a function of time but is subject to strong aspect effects. Total vegetation cover and moss cover are highest on outwash deposits, possibly due to a sheltered aspect and greater uniformity of the outwash surface. Measured albedo exhibits a modest positive correlation with total vegetation cover and a modest negative correlation with rock and soil exposure. The strongest positive correlation was found between albedo and moss cover. The differences in brightness between moraines and outwash deposits are evident visually at the landscape scale on satellite photographs and quantifiable by image-processing software.

Record of aeolian processes in Pleistocene deposits in the foreland of the European sand belt

Abstract This article presents the degree of aeolization of Pleistocene deposits in the foreground of the European sand belt in southern Poland. Ten of the 13 sites were established in the Oświęcim Basin and three in the south part of the Silesian Upland. Attention was focused on four types of deposits formed during three glaciations (Sanian, Odranian, Vistulian): boulder clay, fluvioglacial sands and gravels, end moraine deposits, and aeolian sands. Quartz grain abrasion (for the 0.8–1.0 mm fraction) was examined by mechanical graniformametry and the morphoscopic method. The record of aeolian processes in analyzed deposits is the presence of quartz grains RM (very well-rounded and mat) and EM/RM (moderately rounded and mat). They were found in deposits of various origins and ages but in variable proportions. Considering only the average percentage of grains RM, it should be regarded that abrasion of deposits is low in the case of fluvioglacial deposits, moderate in the case of glacial deposits, and good in the case of aeolian deposits. However, the key factor in determining the degree of abrasion is the share of EM/RM grains, which in the abovementioned deposits are seven, three, and twice as many as RM grains. Therefore, the most noteworthy research result is the very high total share of grains with aeolian abrasion (RM + EM/RM), amounting on average to 84.1% for Odranian fluvioglacial deposits, 86.7% for Sanian glacial deposits and 92.6% for Late Glacial aeolian deposits. It means that in the study area, glacial and fluvioglacial transport included deposits with good aeolian abrasion obtained in the periglacial environment before the transgression of the ice sheets. Probably due to the longer persistence of periglacial conditions in southern Poland, compared to its central and northern parts, the degree of aeolization of fluvioglacial and glacial deposits is better. At the same time, there is a significant differentiation in the aeolization of fluvioglacial deposits within the outwash plain in the foreland of the maximum extent of the Odranian ice sheet. In its proximal part, near the front of the ice sheet, fluvioglacial deposits are characterized by much worse abrasion of quartz grains than in the distal part.

Dating fractures using luminescence

Rock fracturing (cracking) is a universal process that drives and limits chemical degradation, sediment production and erosion, and deterioration of infrastructure. Despite extensive research gains in rock mechanics on one hand and geochronology on the other, there remains a glaring gap in our ability to understand the long term evolution of natural, in situ fractures. Here we develop a novel fracture exposure dating technique, grounded in modern advances in luminescence geochronology. We apply our new dating method to a granitic boulder from a glacial outwash terrace in California, US. We conclude that the longest, clast-splitting E-W fracture appeared shortly after the boulder's deposit, whereas the secondary N-S fracture appeared 5 ka after the deposition, approximately correlating with the Last Glacial Maximum and Younger Dryas periods of the region, respectively. However, dating of the third fracture (<< 50 µm width) which does not fully split the rock, is ambiguous due to negligible daylight penetration and poor determination of fracture width. The fracture dating method presented herein brings with it the potential to decipher relationships that are crucial for the interpretation and modeling of, for example, long-term landscape and atmospheric evolution relating rock weathering to climate change and erosion.

Southern limit of the Patagonian Ice Sheet

The southern limit of the Patagonian Ice Sheet at glacial maxima is poorly constrained due to a paucity of field data. This particularly applies to southern outlet glaciers of the Cordillera Darwin whose full extents have been debated by glacial geologists since 1899 CE, introducing uncertainty into estimates of total ice volume. Here we report on the stratigraphy of exposed stratigraphic sections on the west coast of Isla Hermite which include glacial diamict with discontinuous boulder pavement, overlain by successions of peats and sandy silt. The location of these sections, orientation of clasts within the glacial diamict, and geomorphology of the adjacent marine trough, suggest that an ice stream extended south from an ice centre at Cordillera Darwin across an extended Magellan outwash plain, through Paso Mantellero, to Islas Hermite and Cabo de Hornos (Cape Horn). This was similar in extent to the Canal Beagle and Lago Fagnano Ice Lobes which extended to the east. Retreat occurred sometime before 12,880 cal yr BP based on radiocarbon dated peat macrofossils immediately overlying the glacial diamict. We discuss whether this is a close minimum age, or a product of delayed onset of peat accumulation at the sampling site.

Similarity and Change Detection of Relief in a Proglacial River Valley (Scott River, SW Svalbard)

This study focuses on contemporary geomorphic changes in the proglacial valley floor of the Scott River catchment (northwest of Wedel Jarlsberg Land, southwestern Spitsbergen). The similarity and variability of landforms along the entire 3.3 km length of the unglaciated valley floor was assessed using precision terrestrial laser scanning (TLS) measurements made in July/August 2010–2013. Digital terrain models (DTMs) were generated from the high-resolution TLS survey data, followed by a geomorphon map, which was then used for a similarity and changes of morphology analysis performed with GeoPAT2 software. The study revealed a large spatial variation of contemporary processes shaping the valley floor and changes in its morphology. Their spatial distribution relates to the geologically determined split of the valley floor into three morphological zones separated by gorges. The upper gorge cuts the terminal moraine rampart, which limits the uppermost section of the valley floor, which is up to 700 m wide and is occupied by the outwash plain. The study showed that this is the area characterised by the greatest dynamics of contemporary geomorphic processes and relief changes. The similarity index value here is characterised by a large spatial variation that in some places reaches values close to 0. In the middle section stretching between the upper gorge (cutting the terminal moraine) and the lower gorge (cutting the elevated marine terraces), a much smaller variability of processes and landforms is observed, and the found changes of the valley floor relief mainly include the area of braided channel activity. Similarity index values in this zone do not fall below 0.65. The lowest section, the mouth of the alluvial fan, on the other hand, is characterised by considerable spatial differentiation. The southern part of the fan is stable, while the northern part is intensively re-shaped and has a similarity index that locally falls below 0.5. The most dynamic changes are found within the active channel system along the entire length of the unglaciated section of the Scott River. The peripheral areas, located in the outer zones of the valley floor, show great stability.

Genetic variation and origin of mountain birch on a recently colonized glacial outwash plain by Vatnajökull glacier, southeast Iceland

Genetic variation and origin of mountain birch on a recently colonized glacial outwash plain by Vatnajökull glacier, southeast Iceland