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Sandur plains are extensive sedimentary bodies formed in proglacial settings by glaciofluvial processes. Icelandic sandar have been hypothesised to be comprised of thick alluvial successions that provide critical insight into the processes that contributed to their formation and evolution. However, to‐date, most sandar research has focused on the analysis of sedimentary successions associated to topographically‐confined and small‐scale systems. These, however, do not capture the variety or scale of processes that influence sandar architecture. Therefore, detailed subsurface analysis of large‐scale and unconfined sandar is vital to understand how these systems respond to fundamental drivers, such as: (i) glacier oscillations, and (ii) episodic sediment flux from glacier outburst floods (aka. jökulhlaups). We report an extensive, low‐frequency (40 & 100 MHz) ground‐penetrating radar (GPR) survey of the ice‐proximal component of a large‐scale (~1300km2 $\unicode{x0007E}1300\,{\text{km}}^{2}$) active sandur in southeast Iceland. A bright and continuous reflection (PR1) is identified within all radargrams and provides a boundary between pre‐LIA and LIA to present‐day sedimentation. GPR data reveals a ~50 m thick ice‐proximal sediment wedge that is attributed to jökulhlaup and surge‐related glaciofluvial activity during the Little Ice Age (LIA). An approximate rate of deposition of 0.2–0.65 m a−1 ${{\rm{a}}}^{-1}$ has been calculated for the sediment wedge above PR1. Furthermore, we propose an extensive, sandur‐wide, pre‐LIA ice marginal limit of Skeiðarárökull, southeast Iceland, based on observations reported here and in previous work. [ABSTRACT FROM AUTHOR]

In May 2019, over 50 springs were identified at a sandur-lava field–wetland complex in Southeast Iceland and a subset was selected for further investigation including monitoring water levels, discharge, and water chemistry. Between May and September 2019, springs at the study site had relatively stable water levels and temperatures (4–5 °C), although heavy rains (>10 mm) corresponded with increased water levels and/or temperatures at some springs. Together, the water level, temperature, and stable isotope data suggest that the springs at the study site are fed by older groundwater from an aquifer that is recharged by precipitation. Spikes in water level indicated that at least one spring at the edge of the sandur also received floodwater and shallow subsurface flows from the glacial-fed Brunná River. One wetland spring was further monitored over the water year (October 2019 to October 2020). Like other springs, water levels and temperatures remained relatively stable, fluctuating with inputs of precipitation. Longer-term studies will be needed to gain an improved understanding of seasonal spring vulnerability to climate change and their role in the functioning of a coastal wetland in Southeast Iceland. HIGHLIGHTS Various springs were identified in a sandur, lava field, and wetland landscape in Southeast Iceland.; Wetland springs had stable water levels and temperatures but water levels in other springs were modified by floodwaters of the glacial Brunná River; Baseline hydrological data (water levels, temperature) are provided for springs that warrant long-term monitoring in light of climate warming.; An illustration showing the proposed mechanism of spring discharge at a coastal wetland, Southeast Iceland. Springs in a wetland bordered by a lava field and a sandur have relatively stable hydrology owing to a continuous supply of groundwater. Some springs receive inputs from runoff from the lava field and wetland and shallow surface flows from the sandur as well.

In May 2019, over 50 springs were identified at a sandur-lava field-wetland complex in Southeast Iceland and a subset was selected for further investigation including monitoring water levels, discharge, and water chemistry. Between May and September 2019, springs at the study site had relatively stable water levels and temperatures (4-5 °C), although heavy rains (.10 mm) corresponded with increased water levels and/or temperatures at some springs. Together, the water level, temperature, and stable isotope data suggest that the springs at the study site are fed by older groundwater from an aquifer that is recharged by precipitation. Spikes in water level indicated that at least one spring at the edge of the sandur also received floodwater and shallow subsurface flows from the glacial-fed Brunná River. One wetland spring was further monitored over the water year (October 2019 to October 2020). Like other springs, water levels and temperatures remained relatively stable, fluctuating with inputs of precipitation. Longer-term studies will be needed to gain an improved understanding of seasonal spring vulnerability to climate change and their role in the functioning of a coastal wetland in Southeast Iceland. [ABSTRACT FROM AUTHOR]

This research departs from the background that Sandur has a form of sublimation of transcendent normativity values conveyed through folk theater products. The main focus of the problem's formulation in this study is to analyze the symbol system in Sandur, which is to connect to the meaning of transcendence normativity to be associated with the area of civilized society in the era of globalization. The aim is to prove the existence of the normative meaning of transcendence from the symbol system of Sandur's spectacle and to implement the meaning of the normativity of the transcendence of Sandur as an effort to civilize society to face the negativity of globalization. The analysis in this study was carried out using descriptive qualitative methods through observation, interviews, documentation, and literature, then described based on the concept of Clifford Geertz's interpretive anthropology. The results obtained in this study are (1) the symbol system in Sandur's rituals, scenes, and songs has a transcendent normativity in the form of Mutmainah's attitude and Beyond meaning, as a network of interactions and relationships in the vertical and horizontal dimensions, and (2) the transcendence civilization of Sandur's spectacle in the era of globalization through Beyond meanings and attitudes Mutmainah to face the negative culture of globalization that allows the occurrence of cultural and moral decadence. The problem that becomes the focus of the transcendence civilization of Sandur's spectacle in this study is not rejecting the achievement of globalization progress but rather an attempt to internalize the values in the sign of globalization to maintain the mentality of cultural ecstasy of the people born of transcendence normativity. [ABSTRACT FROM AUTHOR]

Abstract The study analyses a 7.5-m-thick sedimentary succession deposited in the largest sandur (the Gwda sandur, a glacial outwash plain) in NW Poland, during the late Weichselian (MIS 2). Although the study site is located in the distal zone of the sandur, its sedimentological features and palaeohydrological parameters reflect the presence of an energetic, powerful environment typical of the proximal zone. Three sedimentary units were recognized in the studied sedimentary succession: (1) lower unit — fine-grained sands with ripple cross-lamination and horizontal lamination; (2) middle unit — gravelly coarse-grained sands and sandy gravels with planar cross-stratification; and, (3) upper unit — sands and gravelly sands with trough cross-stratification. Although the age of deposition of the sandur is accepted to be convergent with that of end-moraines of the same phase, the sediments in the distal zone of the Gwda sandur correlate with an earlier glaciation phase/subphase. Our findings hint at a complex problem: large sandurs such as the Gwda sandur were probably deposited over a long time, and their successions might record the textural and structural features of the proximal subenvironment, even in their distal parts due to deglaciation-related shifting of the proximal zone of a sandur. This paper presents a new approach to analysing the depositional processes in large sandurs, shows a new light on glaciofluvial water supply dynamics of distal parts of sandurs, and may solve several fundamental problems related to the sandur deposition.

Geoheritage sites are gaining more and more importance due to their natural beauty and curiosity they arouse, besides their value as objects of study and research. Going by the vast geodiversity in India, the declared geoheritage sites are far less and thus, there is a scope to recognize and develop more across the country. The Karnataka State in southern India with rocks and landforms of antiquity offers one of the excellent provinces for recognizing geoheritage sites. Here, spectacular structural, textural, geomorphological and ancient life-form features have been studied and mapped and they could be sites of educational, scientific, research, and esthetic values, besides tourist attraction. Steep fault gorges in Sandur, lofty granite massifs in Ramanagara, natural rocky sculptures in Mudgal, abandoned open cast iron ore mines amid outstanding scenic beauty in Kudremukh, typical spinifex textures in the Archaean ultramafic lavas in Banasandra and Gattihosahalli and stromatolitic structures in Chitradurga schist belt are some of the excellent features worth declaring as geoheritage sites, which could add to the existing list of 4 such sites already declared and protected in the State. Most of the sites which are being proposed now are in mining/quarrying areas and need urgent attention for their conservation. Some of them are already facing irreversible damage and therefore it is time that their scientific value is realized and conserved. SWOT analysis has been carried out for these sites and strategies recommended by analyzing the TOWS matrix for their conservation. It is recommended that the Geological Survey of India (GSI) in coordination with the State Department of Mines and Geology (DMG) should play a key role in this endeavor with assistance from academic Institutions, Private Exploration Companies, NGOs, and individual geoscience professionals. The Government should appoint geoscience representatives on the “Boards” meant to draw policies on nature conservation. The fund available in “District Mineral Foundation,” collected as a share of the royalty for mineral mining, could be utilized to protect and maintain the identified geoheritage sites in the respective districts of the State. [ABSTRACT FROM AUTHOR]

The study analyses a 7.5-m-thick sedimentary succession deposited in the largest sandur (the Gwda sandur, a glacial outwash plain) in NW Poland, during the late Weichselian (MIS 2). Although the study site is located in the distal zone of the sandur, its sedimentological features and palaeohydrological parameters reflect the presence of an energetic, powerful environment typical of the proximal zone. Three sedimentary units were recognized in the studied sedimentary succession: (1) lower unit — fine-grained sands with ripple cross-lamination and horizontal lamination; (2) middle unit — gravelly coarse-grained sands and sandy gravels with planar cross-stratification; and, (3) upper unit — sands and gravelly sands with trough cross-stratification. Although the age of deposition of the sandur is accepted to be convergent with that of end-moraines of the same phase, the sediments in the distal zone of the Gwda sandur correlate with an earlier glaciation phase/subphase. Our findings hint at a complex problem: large sandurs such as the Gwda sandur were probably deposited over a long time, and their successions might record the textural and structural features of the proximal subenvironment, even in their distal parts due to deglaciation-related shifting of the proximal zone of a sandur. This paper presents a new approach to analysing the depositional processes in large sandurs, shows a new light on glaciofluvial water supply dynamics of distal parts of sandurs, and may solve several fundamental problems related to the sandur deposition. [ABSTRACT FROM AUTHOR]

Studies have documented that recent anthropogenic climate change has caused increased vegetative growth on arctic tundra landscapes, resulting in increased carbon storage (in biomass and soil), but decreased albedo and increased energy budgets. The glacial outwash sandplains (sandurs) of Iceland offer an interesting landscape comparison. Here, glacio-fluvial deposits of basaltic volcanic sands and gravels form a low albedo surface (mean 0.11) that stores little carbon (< 0.1%). Conversion of the barren surface to a moss-dominated heath in recent decades increased albedo substantially (mean 0.24), contrary to the general trend on Arctic tundra landscapes, and also increased soil carbon (> 0.2%). The environmental benefits of increased albedo and carbon sequestration highlight the importance of considering the specific processes of landscape change in projecting future environmental changes.

A diverse terrain is one of the essential natural features of a balanced landscape and the specific features of its geomorphological units (sandur, moraine) contribute to regional diversity. The present work describes research designed to verify the hypothesis that the diversity of flora in the ecotone zone of woodland in Poland relates to variability both in the terrain and in land use. By using phytoindication it was possible to assess differentiation in the surfaces under study. It was found that land use (agricultural and forest use) was responsible for the occurrence of a positive interrelationship between trophy and synanthropisation values, no matter what kind of geomorphological unit there was. On the basis of the species composition in the areas under research, within the ecotone zone of woodland, it was established that in the area within moraine which had previously been used agriculturally there was a cumulation of species due to habitat diversity in ecological niches resulting from the terrain, the amount of mineral nutrients in the soil and a large amount of, in particular, native and neutral species in the gene pool. [ABSTRACT FROM AUTHOR]

A 2.5 km stretch of a sandur (glacial outwash plain) neighbouring a wetland in South-east Iceland was monitored from 1 September 2015 to 2 September 2016. Improved understanding of the hydrological regime at this sandur-wetland boundary is warranted as local farmers are losing ground to the frequent flooding of their wet meadows despite the existence of elevated berms. A series of water wells were installed across a sandur-wetland boundary, to monitor water table fluctuations, determine flooding extent and assess groundwater inflow. Flooding occurred rapidly in the sandur during 19 weather events, which included modest and heavy rainfall, and glacial outburst floods (jökulhlaups). Water levels on the South-western edge of the wetland responded in sync with the sandur during flooding, indicating a connectivity via groundwater exchange across the coarse, non-vegetated berm. We estimated that between 6 June and 31 August, 11,275 m3 of groundwater flowed from the sandur to this part of the wetland. This contrasted with the South-eastern edge of the wetland, which had an older, vegetated berm. Here, only 7446 m3 of groundwater flowed from the sandur to the wetland. Overall, these modest water inputs accounted for 76% of seasonal evaporation loss from the wetland (191 mm). [ABSTRACT FROM AUTHOR]

Studies have documented that recent anthropogenic climate change has caused increased vegetative growth on arctic tundra landscapes, resulting in increased carbon storage (in biomass and soil), but decreased albedo and increased energy budgets. The glacial outwash sandplains (sandurs) of Iceland offer an interesting landscape comparison. Here, glacio-fluvial deposits of basaltic volcanic sands and gravels form a low albedo surface (mean 0.11) that stores little carbon (< 0.1%). Conversion of the barren surface to a moss-dominated heath in recent decades increased albedo substantially (mean 0.24), contrary to the general trend on Arctic tundra landscapes, and also increased soil carbon (> 0.2%). The environmental benefits of increased albedo and carbon sequestration highlight the importance of considering the specific processes of landscape change in projecting future environmental changes. [ABSTRACT FROM AUTHOR]

High latitude dust is an important contributor to the global dust cycle, which affects the radiative balance of the atmosphere. The frequency and severity of dust events are driven by variables such as wind speed, precipitation, temperature, surface cover type, and volcanic activity. The extent of impact of glacial retreat is yet to be determined, but glacial outburst floods, known as jökulhlaups, have been suggested to be a significant factor in the seasonal pattern of dust activity, with major jökulhlaups being attributed as a cause for an increase in dust activity in their subsequent year. However, in examination of ten meteorological stations from 1950 to 2009, there does not appear to be sufficient evidence that jökulhlaups are a significant driver of Iceland’s dust activity. Additionally, taking into account a larger range of dust codes, contributions from Icelandic dust plumes are found to be greater than previously assumed, with an average of 128 dust days per year as compared to a previously determined average of 34 dust days annually.

During the Pomeranian phase of the Weichselian glaciation (~17-16 ka), the Toruń-Eberswalde ice-marginal valley (NW Poland and easternmost Germany) drained water from the Pomeranian ice sheet, while intensive aeolian processes took place across Europe in the foreland of the Scandinavian ice sheet (‘European Sand Belt’). The micromorphology of the quartz grains in the Toruń-Eberswalde ice-marginal valley shows no traces of these aeolian processes, or only vague signs of aeolian abrasion. This is unique among the aeolian sediments in other Pleistocene ice-marginal valleys in this part of Europe. The study of the surfaces of the quartz grains shows that the supply of grains by streams from the south was minimal, which must be ascribed to the climate deterioration during the Last Glacial Maximum, which resulted in a decrease of the discharge of these extraglacial rivers to the ice-marginal valley.

During the Pleistocene the Scandinavian ice sheet drained huge quantities of sediment-laden meltwaters. These meltwaters supplied ice-marginal valleys that formed parallel to the front of the ice sheet. Not without significance was the supply of ice-marginal valleys from extraglacial rivers in the south. Moreover, periglacial conditions during and after sedimentation in ice-marginal valleys, the morphology of valley bedrocks, and erosion of older sediments played important roles in the depositional scenarios, and in the mineralogical composition of the sediments. The mechanisms that controlled the supply and deposition in ice-marginal valleys were analysed on the basis of a Pleistocene ice-marginal valley that was supplied by northern and southern source areas in the immediate vicinity. Investigations were conducted in one of the largest ice-marginal valleys of the Polish-German lowlands, i.e., the Toruń-Eberswalde ice-marginal valley, in sandurs (Drawa and Gwda) supplied sediments and waters from the north into this valley, and on extraglacial river terraces (pre-Noteć and pre-Warta rivers), formed simultaneously with the sandurs and ice-marginal valley (Pomeranian phase of Weichselian glaciation) supplied sediments and waters from the south into this valley. A much debated question is how similar, or different, depositional processes and sediments were that contributed to the formation of the Toruń-Eberswalde ice-marginal valley, and whether or not it is possible to differentiate mostly rapidly aggraded sandur sediments from ice-marginal valley sediments. Another question addresses the contribution of extraglacial feeding of the Toruń-Eberswalde ice-marginal valley. These matters were addressed by a wide range of analyses: sediment texture and structure, architectural elements of sediments, frequency of sedimentary successions, heavy-mineral analysis (both transparent and opaque heavy minerals), analysis of rounding and frosting of quartz grains, and palaeohydrological calculations. Additionally, a statistical analysis was used. The specific depositional conditions of distribution of sediments in ice-marginal valley allow to distinguish new environment of ice-marginal valley braided river. The spectrum of depositional conditions in the Toruń-Eberswalde ice-marginal valley and their specific palaeohydraulic parameters allow to distinguish three coexisting zones in the ice-marginal valley braided-river system: (1) deep gravel-bed braided channel zone with extensive scours, (2) deep sand-bed braided channel zone with transverse bars, and (3) marginal sand-bed and gravel-bed braided channel zone with diamicton and breccia deposition, which were characterised in detail. Some of the results have been published previously, which is why they are discussed in the present paper within the context of new data

Proglacial groundwater-fed features, such as seeps, substantially impact proglacial geomorphology, hydrology, and ecology. However, there is a paucity of research on the impacts of climate change and glacier retreat on the extent of these important features. This paper aims to investigate the impact of glacier retreat on proglacial groundwater levels and on the extent of groundwater-fed seeps. Research has taken place in western Skeiðarársandur, the large proglacial outwash plain of Skeiðarárjökull, a retreating temperate glacier in southeast Iceland. Changes in the extent of proglacial groundwater seeps were mapped using historical aerial photographs from 1986, 1997, and 2012. Proglacial groundwater levels were monitored in shallow boreholes between 2000 and 2012. The western margin of Skeiðarárjökull has retreated approximately 1 km beyond its position in 1986. However, this retreat was punctuated by short periods of readvance. The geomorphology and groundwater systems at the site were substantially impacted by the November 1996 jökulhlaup, whose deposits altered approximately 18% of the area of groundwater seeps. The surface areas of groundwater seeps and lakes in the study area have declined by ~97% between 1986 and 2012. Most of the decline took place after 1997, when the mean annual rate of retreat increased three-fold. Groundwater levels also declined substantially between 2000 and 2012, although this trend varies spatially. The paper provides a conceptual model of the controls on proglacial shallow groundwater systems. Direct impacts of glacier retreat are suggested as the main cause for the declines in proglacial groundwater levels and in the extent of groundwater seeps. These declines are expected to adversely impact sandur ecology. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Density differences among the various heavy-mineral species appear to be the main factor responsible for their sorting in glaciofluvial and fluvial environments. Sediments from two sandurs (stretching perpendicular to the Weichselian ice-sheet front) and a terrace of the Toruń-Eberswalde ice-marginal valley (extending parallel to the Weichselian ice-sheet front) in NW Poland support this idea clearly. The deposits investigated were formed during the Pomeranian phase of the Weichselian glaciation. Heavy-mineral and sedimentological analyses of these sediments indicate that most changes in the proportion of the various heavy-mineral species in gravelly and sandy sediments can be ascribed to changes in the flow regime, which is, in turn, related to the density of the various heavy-mineral species. In addition, the turbulence of the current and the bedform played a role in the sorting. The sedimentation rate also affected the heavy-mineral composition of the sandur and ice-marginal valley sediments. Furthermore, the proportions of some heavy minerals depend on the transport distance, which is well expressed by differences that occur over the investigated distance of 90 km of the ice-marginal valley. It appears that some heavy-mineral species are good tools for reconstructing sorting processes. Heavy minerals deposited by streams with a fast-changing discharge and a high accumulation rate (which is common for glaciofluvial streams) can, by combining data about the composition of the assemblages with data about the characteristics (size, rounding, colour, etc.), help in reconstructing palaeo-flow regimes and in estimating the turbulence, transport distance and mode of sediment transport in the streams. [ABSTRACT FROM PUBLISHER]

Aeolian dune fields characterized by partly vegetated bedforms undergoing active construction and with interdune depressions that lie at or close to the water table are widespread on Skeiđarársandur, Southern Iceland. The largest aeolian dune complex on the sandur covers an area of 80 km2 and is characterized by four distinct landform types: (i) spatially isolated aeolian dunes; (ii) extensive areas of damp and wet (flooded) interdune flat with small fluvial channels; (iii) small aeolian dune fields composed of assemblages of bedforms with simple morphologies and small, predominantly damp, interdune corridors; and (iv) larger aeolian dune fields composed of assemblages of complex bedforms floored by older aeolian dune deposits that are themselves raised above the level of the surrounding wet sandur plain. The morphology of each of these landform areas reflects a range of styles of interaction between aeolian dune, interdune and fluvial processes that operate coevally on the sandur surface. The geometry, scale, orientation and facies composition of sets of strata in the cores of the aeolian dunes, and their relationship to adjoining interdune strata, have been analysed to explain the temporal behaviour of the dunes in terms of their mode of initiation, construction, pattern of migration, style of accumulation and nature of preservation. Seasonal and longer-term flooding-induced changes in water table level have caused episodic expansion and contraction of the wet interdune ponds. Most of the dunes are currently undergoing active construction and migration and, although sediment availability is limited because of the high water table, substantial aeolian transport must occur, especially during winter months when the surface of the wet interdune ponds is frozen and sand can be blown across the sandur without being trapped by surface moisture. Bedforms within the larger dune fields have grown to a size whereby formerly damp interdune flats have been reduced to dry enclosed depressions and dry aeolian system accumulation via bedform climb is ongoing. Despite regional uplift of the proximal sandur surface in response to glacial retreat and unloading over the past century, sediment compaction-induced subsidence of the distal sandur is progressively placing aeolian deposits below the water table and is enabling the accumulation of wet aeolian systems and increasing the likelihood of their long-term preservation. Wet, dry and stabilizing aeolian system types all co-exist on Skeiđarársandur and the dunes are variously undergoing coeval construction, accumulation, bypass, stabilization and destruction as a result of interactions between localized factors. [ABSTRACT FROM AUTHOR]

Abstract: This paper examines the controls on the morphology and sedimentology of a valley-confined proglacial outwash plain or ‘sandur’ in West Greenland subject to glacial outburst floods (jökulhlaups). Jökulhlaup flow conditions observed during a recent (1987) flood are linked to sandur sedimentology and morphological change. Backwater effects over the distal sandur resulted in a reduction of stream power despite increasing discharge. Bar units were typically large. Bar front advance of 60 m during 1987 jökulhlaup occurred prior to waning stage bar dissection by chute channels. Channel change was confined to the distal sandur, due to the greater erodibility of the finer-grained bars. A temporary zone of sediment storage prevailed at the transition between free flowing and ponded flood waters until flood powers increased during waning flood stage as backwater effects were removed. Extension of pre-existing high-relief amplitude bars within the distal sandur records sedimentation related to at least eight jökulhlaups, whilst lower-relief amplitude, proximal sandur sediments provide a composite record of the last high stage jökulhlaup flows. Backwater conditions during jökulhlaups have increased the rapidity of spatial variation of grain sizes and fluvial facies types. Complex, within-event, sediment reworking and routing is generated by the onset and break up of backwater effects. The role of local topography is therefore crucial when interpreting the sedimentary record of former proglacial channels potentially subject to jökulhlaups. This study may prove useful in identifying the presence of flood cycles within palaeo-fluvial systems in both formerly glaciated and non glaciated areas. [Copyright &y& Elsevier]

Abstract: A coastal aeolian dune field on the distal parts of Sólheimasandur, southern Iceland is currently undergoing active construction. Ongoing sand deflation in the foreshore is demonstrated by the preservation of sand ridges in the downwind lee of obstacles, while a backshore sandsheet is characterised by actively accumulating long-wavelength wind ripples. The main region of aeolian accumulation is in the immediate backshore where sand has accumulated to a thickness of up to 8 m and is largely stabilized by vegetation. Surrounding interdune areas have undergone repeated flooding by fluvial incursions from the adjacent Jökulsá River, and are characterised by mud drapes which lap against the lower flanks of neighbouring dunes. Widespread sand adhesion structures testify to the often damp nature of the substrate. Over 1200 vegetated and stabilized dunes (nebkhas) occupy a 5 km2 area of wind-deflated gravel sandur plain downwind from the main site of aeolian accumulation. The nebkhas show strong relationships between plan form shape and height, indicating that they have attained equilibrium morphology for the prevailing climatic conditions. Within the nebkha field, dunes demonstrate a predictable downwind decrease in height, spatial concentration and degree of sand stabilization. A time series of aerial photographs documents the temporal evolution of the dune field and demonstrates that aeolian accumulation commenced about 1940 and has been ongoing to the present day. Prior to 1940, repeated outburst floods associated with catastrophic lake drainage events from the Sólheimajökull glacier 8 km inland were of sufficient magnitude to repeatedly destroy any incipient aeolian bedforms that developed. Although strong onshore winds and high rates of sediment supply promote aeolian sediment transport, dune field development is rare in humid boreal and sub-arctic climates as encountered in southern Iceland because the availability of sediment for aeolian transport is usually severely limited by damp substrate conditions. Thus, the airflow tends to be undersaturated with respect to its potential sand transporting capacity and dune construction can only occur because of the stabilizing influence of vegetation. [Copyright &y& Elsevier]

Abstract: Proglacial fluvial sedimentary systems receive water from a variety of sources and have variable discharges with a range of magnitudes and frequencies. Little attention has been paid to how these various magnitude and frequency regimes interact to produce a distinctive sedimentary record in modern and ancient proglacial environments. This paper reviews the concept of magnitude and frequency in relation to proglacial fluvial systems from a geomorphic and sedimentary perspective rather than a hydrological or statistical perspective. The nature of the meltwater inputs can be characterised as low-magnitude–high-frequency, primarily controlled by ablation inputs from the source glacier, or high-magnitude–low-frequency, primarily controlled by ‘exceptional’ inputs. The most important high-magnitude–low-frequency inputs are catastrophic outburst floods, often referred to by the term jökulhlaup (Icelandic for glacier-burst). Glacier surges are an additional form of cyclical variation impacting the proglacial environment, which briefly alter the volumes and patterns of meltwater input. The sedimentary consequences of low-magnitude–high-frequency discharges are related to frequent variations in stage, the greater directional variability that sediment will record, and the increased significance of channel confluence sedimentation. In contrast, the most significant characteristics of high-magnitude–low-frequency flooding include the presence of large flood bars and mid-channel ‘jökulhlaup’ bars, hyperconcentrated flows, large gravel dunes, and the formation of ice-block kettle hole structures and rip-up clasts. Glacier surges result in a redistribution of low-magnitude–high-frequency processes and products across the glacier margin, and small floods may occur at the surge termination. Criteria for distinguishing magnitude and frequency regimes in the proglacial environment are identified based on these major characteristics. Studies of Quaternary proglacial fluvial sediments are used to determine how the interaction of the various magnitude and frequency regimes might produce a distinctive sedimentary record. Consideration of sandur architecture and stratigraphy shows that the main controls on the sedimentary record of proglacial regions are the discharge magnitude and frequency regime, sediment supply, the pattern of glacier advance or retreat, and proglacial topography. A model of sandur development is suggested, which shows how discharge magnitude and frequency, in combination with sandur incision and aggradation (controlled by glacier advance and retreat) can control sandur stratigraphy. [Copyright &y& Elsevier]

Present-day sandurs are formed under conditions that are geologically exceptional. Consequently, they show characteristics that differ from those formed under more common conditions. We show this on the basis of Polish examples formed during the last ice age. A good understanding of sandur formation requires models that are not based on the present-day situation. [Copyright &y& Elsevier]

In subaerial volcaniclastic sequences structures formed by ice blocks can provide information about a volcano's history of lahar generation by glacier melt. At Volcán Hudson in Chile, catastrophic lahars were initiated by eruption-induced melting of glacier ice in August and October 1991. They transported large ice blocks 50 km down the Rio de los Huemules valley to the sea. Large current crescents with lee-side lenses were formed where ice blocks were deposited during waning stages of the flood. When stranded blocks of ice melted, they left cone-shaped and ring-shaped heaps of ice-rafted debris on the sediment surface. Several hundred ice blocks were completely buried within the aggrading lahar sediment, and when these melted circular collapse pits formed in the sediment. Collapse types included subsided coherent blocks of sediment bounded by an outward-dipping ring-fracture, trapdoor structures with horseshoe-shaped fractures, downsag pits with centroclinal dips locally up to 60°, pits with peripheral graben and crevasses, piecemeal (highly fragmented) collapse structures and funnel-shaped pits containing disaggregated sediment. A sequence of progressive collapse is inferred in which initial downsag and subsidence on an outward-dipping ring fracture produces a small diameter pit. This is followed by widening of the pit by progressive development of concentric ring fractures and downsag outside the early formed pit, and by collapse of overhanging pit walls to produce vertical to inward-dipping walls and aprons of collapse debris on the pit floor. The various structures have potential for preservation even in regions prone to high rainfall and flooding, and they can be used to indicate that former lahars contained abundant blocks of ice. [ABSTRACT FROM AUTHOR]