Abstract Periglacial and paraglacial (cold-climate) environments, located outside the margins of past and present ice sheets but responding to similar climate forcings, are key to identifying climate change effects upon the Earth system ( Warburton 2007 ). These environments are relicts of cold Earth processes and thus are most sensitive to climate change that took place during the last glacial–interglacial transition, and at the present time under enhanced global climate warming. These effects include changes in humidity/aridity and radiation balance, which are most significant in the higher latitudes and at high elevations where periglacial and paraglacial environments are most common and where these environments occur near their climatic limits ( Harris 1994 ; Matsuoka 2001 ). Variations in humidity and radiation balance have implications for heat budgets, water balance, land surface stability, downslope sediment supply, biodiversity and biogeochemical cycling (e.g. Schneider et al. 1999 ; Scott et al. 2008 ). The dynamics of cold-climate environments are, therefore, strongly controlled by external climatic forcing; and hence periglacial and paraglacial processes (and the landforms and sediments that result from them) can be considered as a transient response to the landscape disturbance and land surface instability that accompanies climatic change ( Hewitt et al. 2002 ). This view of a transient landscape responding to environmental disturbance is significant because it underpins influential deterministic and steady-state models in cold-climate science ( Church & Slaymaker 1989 ; André 2003 ; Warburton 2007 ).These models predict a rapid increase in sediment yield (which results from land surface disturbance) associated with initial climate forcing, followed by exponential decay of sediment yield towards background rates which are achieved as land surfaces are stabilized ( Church & Ryder 1972 ; Ballantyne 2002 ).

Abstract Periglacial geomorphology developed in the 1940s–1960s as a branch of climatic geomorphology, focusing first on Quaternary studies and palaeoenvironmental reconstructions, then on current geomorphic activity in cold regions. The ‘periglacial fever’ of the 1960s–1970s was dominated by the ‘freeze–thaw dogma’: periglacial areas were regarded as necessarily submitted to efficient frost-driven processes ruling over the geomorphic activity. Such a view was severely criticized in the 1980s–1990s based both on monitoring studies and on time–space multiscale approaches that pointed to the need to cross the ‘smokescreen of the periglacial scenery’ to search for the real past and present processes responsible for the landform geometry. The role of non-cold-related processes in the making of ‘periglacial’ landcapes was re-evaluated, and the necessity to better take into account the rock properties and the pre-Quaternary history of slope systems was emphasized. Whereas the part of the cold-related processes was being minimized, the interest of genuine periglacial landforms as geoindicators of climate change was growing, providing a new legitimacy to periglacial geomorphology. Polar and Alpine regions are nowadays considered as key observatories of ongoing climate change, and periglacial geomorphologists are involved in the detection, monitoring and prediction of environmental changes. Finally, the evolution of ‘periglacial geomorphology’ over the past six decades is in accordance with the development of the whole geomorphology. Based on the quantitative and technological revolution, it tends to find a balance between the functional and historical approaches.

Abstract Post-glacial weathering of ice-eroded metamorphic bedrock was investigated in the Røldal area (60°N) of the Hardangervidda Plateau in southern Norway. Quartz veins were used as reference surfaces to determine a mean post-glacial surface lowering rate of 0.55 mm ka −1 . Chemical characteristics of late-season runoff were determined for one catchment (Snøskar) and a chemical erosion rate of 4.9 t km −2 a −1 was obtained. A mean in situ fracture enlargement due to microweathering of 0.12 mm ka −1 was also determined. These rates are low, although comparable with similar environments in cold regions, and suggest that microweathering has had relatively little impact on Holocene landscape evolution. Weathering rind thickness was found to be less on fracture walls than on exposed bedrock surfaces, suggesting fractures have not played a significant role in microweathering. Observations of weathering morphology reveal a range of forms including shallow spalling, tafoni and pseudokarren, indicating locally intense weathering activity. Analysis of interrelationships between multiple weathering indices points to the importance of bedrock microweathering as a precursor to macro-breakdown and landform evolution. The research reasserts the importance of chemical activity in cold environments and the importance of moisture supply for effective microweathering.

Abstract The formation of a palsa is based on the thermal properties of peat. Frozen wet peat has a high thermal conductivity, and therefore cold can penetrate deep into peat layers if the snow cover is thin; while the dry peat in summer insulates the frozen core of a palsa, so that the permafrost core is preserved. The volumetric growth of the palsa is based on the buoyancy effect of the frozen core, which lifts it, causing some water to accumulate under the core, where it freezes during the next winter and forms thin ice layers. Only when the frozen peat core touches the frost-susceptible silt or silty till layer at the bottom of the mire does ice segregation start to play an important role in the formation of the palsa.

Abstract Whilst glaciologists and permafrost researchers investigate ice bodies using similar techniques, there has been surprisingly little collaboration between the two communities. This paper examines the potential benefits of interdisciplinary research into the formation of basal ice beneath glaciers and the origin of massive ice in glaciated permafrost regions. Active collaboration in these areas has already improved our understanding of the formation of basal ice beneath cold-based glaciers, the critical role played by basal freezing in controlling the dynamic behaviour of stagnating ice streams and the significance of glacier–permafrost interactions at the margins of Pleistocene ice sheets. However, in order to promote future collaboration certain obstacles need to be overcome. The contrasting ice-classification schemes employed by glaciologists and permafrost scientists, for example, need to be unified in order to allow detailed comparisons of ice-rich sequences in both environments. This could, in turn, enable exciting research advances, most notably by facilitating the identification of preserved remnants of Pleistocene ice sheets within permafrost regions that provide a potentially invaluable and currently largely untapped source of palaeoglaciological information.

Abstract The terms proglacial and periglacial are well-understood descriptors of contemporary and past environments, but the paraglacial concept is more controversial and has prompted vigorous debate. Definitions are reviewed and the paraglacial concept is considered critically. It is argued that the term ‘paraglacial’ defined as ‘non-glacial processes conditioned by glaciation’ describes landscapes that are adjusted neither to Last Glacial Maximum nor to contemporary geomorphic processes. Where a landscape is paraglacial it can be characterized in terms of rate of change and trajectory of that change. It cannot be defined in relation to glaciers (as in proglacial) or by cold-climate processes (as in periglacial). Almost all paraglacial landforms and all paraglacial landscapes are transient and transitional. An interesting challenge of paraglacial landscapes is then to determine their rates of change; how far they have advanced along the trajectory from glacial to non-glacial; and how to recognize empirically the temporal and spatial relationships between proglacial, periglacial, paraglacial and fluvial landscapes. Implications of this approach to paraglacial landscapes are discussed in relation to historical and dynamic geomorphology.

Abstract A selection of glacial deposits with distinct morphological or stratigraphic forms associated with glaciers is considered with respect to climatic signals and debris inputs at the time of formation. The relationships are by no means simple and consideration is given, in general terms, to the range of conditions that might apply to a range of depositional features now found ‘relict’ in the British Isles. These factors are spatial (including continentality) and altitudinal, as well as climate and climatic variability. Examples, mainly from present-day marginally glacierized environments, are given to illustrate the complexity of these interrelationships. Features included are: plateau glaciers and their outlets, where moraines of the outlet glaciers may not be representative of the overall behaviour; plateau glaciers and remnant blockfields related to time of formation; the formation of moraines and rock glaciers; and protalus ramparts and protalus lobes as functions of ice and debris input, as well as thermal regime. It is suggested that the relative amounts of ice and rock debris are important in the formation of certain features. Understanding these relationships is an on-going process and is required for effectively mapping an interpretation of past local- and medium-scale environmental conditions.

Abstract Rock slope failure (RSF) generates the largest single erosional events in the glacial–paraglacial land system, leaving numerous obvious cavities and less obviously weakened valley walls. Its contribution to trough widening in a mountain range has not previously been systematically quantified. Map-based measures of RSF ‘depth of bite’ are applied to five sample areas in the Scottish Highlands, and a comparator area in north Norway, all in metasediments structurally conducive to mass deformation and block sliding. Problems in applying map-based measures include bedrock cavities remaining partially occupied by failed debris or subsequent infill, and multiple planes of reference. The most practical measure is of maximum recess depth on any single contour ( D MAX ). This is a standardizable single-point indicator of visible impact, not a measure of actual cavity depth, nor an average applying to the whole RSF. In four of the five areas, average D MAX is consistent at 40–45 m. RSF breadth averages 270–600 m over the five areas. RSF affects 9% and 14% of total valley wall length in the two densest RSF areas, rising to 47% and 52% on two specific valley sides. The depth:breadth ratio in areas dominated by slope deformation can be twice that in areas of translational sliding. An evolutionary model of glacial–paraglacial cycling proposes a ‘zone of paraglacial relaxation’ in which RSF is intense in early cycles as fluvial profiles adjust to ice discharge, diminishing with maturity as trough walls become stress-hardened, and reviving in response to neotectonic and glaciological perturbations, notably ice piracy via transfluent breaching. However, a major unknown is the efficacy of glacial exploitation of RSFs: if it takes several cycles to evacuate debris and pare back cavity angles, cumulative RSF impact is lessened. Glacial–paraglacial cycling is a classic positive feedback loop, promoting valley widening beyond the parabolic norm. Preferential exploitation of structure by RSF promotes asymmetrical trough profiles. RSF acts both as a scarp retreat process, and as a slope reduction counterpoint to glacial slope steepening. In landscape evolution, it is a powerful agent in destruction of paleic relief, notably around watersheds that are undergoing breaching by transfluent ice, where trough development and widening is still vigorous.