The role of weathering and pedological processes for the development of sorted circles on Kvadehuksletta, Svalbard - a short report

The presence of silt-rich, fine-grained material at the center of the well-developed sorted circles on Kvadehuksletta, Svalbard, is a precondition for their development. Field work, laboratory work, and data from published studies indicate that the fine-grained material is a dissolution product of the dolomitic bedrock. The silt is accumulated in situ and by slope wash in terrain depressions. Chemical weathering and other pedogenetic processes, such as the translocation of silt, are of great importance in Arctic regions and can create the sedimentological prerequisites for cryogenetic processes, such as frost sorting and cryoturbation. Therefore, the bedrock composition and the composition of surficial material are considered to be important control factors for these processes

Coastal cliff temperatures related to the potential for cryogenic weathering processes, western Spitsbergen, Svalbard

The main purpose of this research was to measure the near surface ground temperatures and describe the main characteristics of the thermal regime of a sheltered arctic coastal cliff. Measurements were made near Ny-Alesund, western Spitsbergen, Svalbard (79°N, 12°E), in a transect across sediments on top of a coastal cliff, in a 8 m high coastal cliff and across the beach below the cliff. Temperatures were logged hourly from August 1987 to August 1988. A local snow cover of 1–4 m on the beach had a strong influence on surface heat exchange, and hence the dynamics of the ground thermal regime. Late winter temperatures in the cliff and backshore sediments were stable and ranged from -5°C to -9°C. At the first snow melt events in spring there was a large heat flux into the ground due to the release of latent heat from refreezing of meltwater. The interpretation of the temperature records leads to a discussion on some aspects of cryogenic weathering. The snow-melt period in spring and summer may be a period of rock fracturing, based on the model of segregation ice growth at subzero temperatures. Steep temperature gradients and available meltwater at the surface favor water migration in the heavily fractured dolomitic limestone even at the low hydraulic conductivities expected at below zero temperatures

Measuring coastal cliff retreat in the Kongsfjorden area, Svalbard, using terrestrial photogrammetry

As part of the international project Arctic Coastal Dynamics, results from two sites for measuring coastal cliff retreat in the Kongsfjorden area in Svalbard (79 ° N, 13 ° E) are presented. The two sites were established in August 2002 and revisited in August 2004. Photographs with stereo coverage were taken at distances of 7 and 15 m from the cliff walls with a 60-mm Hasselblad camera mounted on a theodolite. Fixed points were established by drilling bolts into the cliff wall and were then surveyed. These fixed points were used as control points for orientation of the photogrammetric models. Digital photogrammetry applied to scanned photographs of the sites resulted in a detailed digital terrain model (DTM) for each site and year. The coastal cliff retreat rates were found by differencing the DTMs of 2002 and 2004. As a result of the short distance between camera and cliff, the DTM differencing was accurate down to 10 mm at least. The results show a yearly retreat of 2.7 and 3.1 mm. These rates are taken to be significant as most of the retreat takes place within small areas with rates well above the accuracy limits of the technique. The results are analysed and discussed in light of earlier rock-wall retreat studies in the same area

Mass balance and changes of surface slope, crevasse and flow pattern of Erikbreen, northern Spitsbergen: an application of a geographical information system (GIS)

The polythcrmal valley glacier Erikbreen (79°40?N 12°30?E), northern Spitsbergen, was investigated in 1970 and 1990 using digital photogrammetry and digital elevation model (DEM) techniques. The bottom topography was derived from radio-echo soundings. Based on the DEM, mass balance and changes of surface slope, crevasse and flow pattern were evaluated, and internal ice deformation velocities were calculated. Calculations of the total mass balance show that Erikbreen has not been in equilibrium for the last 20 years. The average surface lowering was 0.38 m/a and the volume had decreased by 5% to 6% from 1970 to 1990 or on the average by 3.5 × 10?1 water. The glacier surface subsided over the whole glacier area except in minor areas with northfacing slopes in the accumulation area. The surface slope and the crevasse pattern, however, did not change significantly during the 20-year-period, except in areas below 100 ma.s.l

Thermal regime of a valley glacier, Erikbreen, northern Spitsbergen

The thermal regime of the valley glacier, Erikbreen, northern Spitsbergen (79°40?N, 12°30?E) was studied using radio-echo sounding and temperature measurements from eight boreholes ranging from 13.5 to 24 m. Radar images indicate a glacier with a two-layered thermal structure. A surface layer of cold ice, 20 to 60 m thick along the centre flow line, extends from an altitude above equilibrium line to the glacier front. This layer represents 20 to 35% of the glacier thickness, except at the floating front, where the cold layer is about 50%. The ice beneath the cold surface layer is interpreted to be temperate. Cold-based areas exist near the glacier margin and in some locations in the accumulation area; the ice is interpreted to be entirely temperate in central parts of the accumulation area at high altitude. Freezing of temperate ice at the base of the cold surface layer is probably the main mechanism of cold ice formation in the frontal parts of Erikbreen. Calculated heat fluxes based on the borehole measurements show that a steady state cold layer 25 to 30 m thick is likely, assuming a surface melting of 1.7 m/y and a maximum water content of 3%. In the frontal parts the calculated mean annual upward heat flux at 10 to 15 m depth is roughly 0.6 W/m2

Mapping and modelling the occurrence and distribution of mountain permafrost

This paper reviews the principles related to the mapping and modelling of the occurrence and distribution of mountain permafrost. It gives a state-of-the art report about this topic and defines future research needs