摘要:

AbstractThe present distribution of permafrost in the northern part of Fennoscandia is as yet very little known. The possible existence of perennial frozen ground may be estimated from climatic data, but meteorological stations are few and scattered. As, furthermore, large areas are marginal in respect of perennial frozen ground, local conditions of topography, material, and climate may influence the formation and preservation of permafrost. Therefore it would be of great value, if the existence of permafrost might be assessed directly from surface features, especially when detectable in aerial photographs. In the paper the periglacial form group of Scandinavia will be elucidated and its potential use as indicator of permafrost be discussed.From engineering-, land survey- and planning aspects there is a growing demand for a more exact knowledge of the regional and local distribution of permafrost in northern Scandinavia. To get as many relevant data as possible in this field, a joint research program by permafrost scientists of the Norden countries would be of great value.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880165

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractField studies in the Jotunheimen, Rondane and Kebnekaise areas provide evidence that vast permafrost occurrences exist in the high mountain areas of Scandinavia. This is also supported by theoretical conclusions. A threefold vertical subdivision for high altitude permafrost is suggested: continuous, discontinuous and sporadic. The mean annual air temperature is a good indicator for the altitudinal limits of these permafrost belts in non-investigated areas, at least for the more continental mountain regions. Among others, ice-cored moraines and rock glaciers are discussed as typical sites where the occurrence of high altitude permafrost is favoured.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880166

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractA brief summary is made of various field studies from Fennoscandia concerned with the origin of palsas, which are peat hummocks with a permafrost core rising above the mire surface. An insulating peat layer is important for preserving the frozen core of the palsa during the summer. Palsa formation needs low winter temperatures to form thick layers of frost, together with water-saturated peat and a thin snow cover. Factors limiting the size of palsas are discussed. Sharp, steep edges, which collect drifting snow, stop the areal growth of palsas. A model for cyclic palsa development is presented.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880167

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractThe results of drillings in dome-shaped palsas are presented. A comparison of the internal structures of these palsas and of previously investigated pingos in northernmost Sweden indicates that the processes of formation may have been similar. Drillings have also shown, that today the ground surrounding the pingos is unfrozen. However, as there are indications of former more common permafrost within the pingo area, as well as in northern Scandinavia in general, it is not unlikely that the pingos date from a period when permafrost was more widespread.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880168

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractIn the area around Abisko and Björkliden some new observations of different types of permafrost mounds have been made. The features include forms which resemble palsas, pingos and frost blisters. The observations are made in an area where several“fossil pingos”have been reported. This paper gives a preliminary description of the observed features, their possible genetic background, terminology and their possible relations to other permafrost features, both recent and fossil, of the region.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880169

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractDeformed structures occurring in terrace deposits of the Bernard River, central Banks Island, are interpreted as soft-sediment deformations, the result of rapid sedimentation and entrapment of excess pore water. Other deformed structures described from terrace deposits of the Kellett River, southern Banks Island, are thought to have resulted from liquifaction and density re-adjustments in the active layer. Since permafrost conditions were involved in the latter, these structures can reasonably be termed periglacial involutions.The presence of both soft-sediment deformations and periglacial involutions in a present periglacial environment emphasises the difficulty of interpreting involutions in Pleistocene sediments of mid-latitudes.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880170

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractSoil moisture, soil temperature, and frost depth have been monitored for two winters in cultivated soil, and, on monoliths, in the laboratory at temperatures well below the freezing point. Time Domain Reflectometry, being a non-destructive technique, has proved successful in showing the progress of frost and thaw fronts, of the considerable portion of water remaining unfrozen throughout the winter, and, of the redistribution of soil water that occurs between growing seasons.Results emphazise the role of the diffuse electric double layer, partly in its relationships to hydraulic conductivity which, although lowered by factor of 10 to 100, never reaches zero in so called frozen soils. At temperatures of Scandinavian winters, in particular under a snowcover, it is shown that an un-broken liquid pathway exists all through the winter soil profile. The importance to frost heave is well-known; the present study emphazises also its importance to creep where it offers a deeper understanding of the slope movements of soil.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880171

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractThis study indicates that vegetation on frost heaved soils is controlled by two main factors: (1) disruptive effects on the belowground parts of the plants when the soil heaves; (2) an increase of nutrient availability, pH, and base saturation following this disturbance. The vegetation changes from a dominance of rhizomatous (mostly graminoids) and woody plants (shrubs and dwarf shrubs) on stable soils, via dominance of dwarf shrubs alone on soils of low disturbance, to dominance of fibrous rooted perennials at the strongest disturbance. I suggest that rhizomatous plants are adapted to grow at sites with a continuous humus cover where they easily can penetrate and exploit the organic matter. They are excluded, however, from frost heaved ground because no continuous humus layer is formed, due to the disturbance. Woody plants are favoured by lack of competition from rhizomatous perennials on soils of low disturbance but they are not able to withstand the disruptive forces of strong frost heaving. The fibrous-rooted plants are not severely damaged even by intense frost heaving since their belowground systems die to a great extent before the onset of freeze-thaw cycles in late autumn. Instead they are problably favoured by the disturbance because competition is reduced, and because they are adapted to high nutrient availability as evidenced by the short lifespan of their root system.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880172

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractAn ongoing geomorphological research project on nivation and local glaciation is testing the following working hypothesis.After the main Weichselian deglaciation in south Sweden, periods of cold tundra conditions returned, e.g. in the Younger Dryas period. Fossil ice-wedge casts and rocks with wind-polished facets and flute marks indicate permafrost climate and strong winds with snow-drifting from easterly and westerly directions. Large masses of drifting snow were trapped in the canyon valleys of Söderäsen and other horst ridges, where nivation hollows and small glacial cirques were slightly rejuvenated. Niveo-eolian sand was deposited in some hollows and also incorporated in some moraine-like deposits. The bedrock hollows and cirques were mainly excavated during the much longer tundra periods before the advances of the Quaternary main ice sheets over Scania. But the hollows survived the erosional impact of the ice sheets.The work to test the hypothesis is making progress, by analysis of the Late-Glacial forms and material in south Sweden, by comparisons with landforms, material and processes in the actual mountain tundra of Abisko in the north, and by comparisons with similar work by scientists in western Norway, northwest England/Scotland and Middle Europe. The studies will also be of general interest in arctic and alpine geomorphology, as they throw light on the genesis of critical types of debris deposits such as small cirque moraine ridges, protalus ramparts, rock-glacier lobes, gelifluction and debris-flow deposits.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880173

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractWithin a study of nivation processes and landforms, the freeze-thaw activity is being measured at two sites in northern and southern Sweden. The aim is to test the hypothesis of active nivation occurring in the periglacial environment of northern Sweden, as opposed to the temperate south, in the present climate. Attempts will be made to relate the freeze-thaw activity to the operation of mass wasting processes at snowpatch sites. The report describes the study sites and the instrumentation used and concludes with some brief comments on initiated measurements.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880174

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor