摘要:

AbstractMiddle and Late Devensian thermal contraction networks and cracks are described from the southern Fenland, Cambridgeshire. They are associated with gravel aggradations of low terraces of the River Great Ouse. Two networks are described, one set younger than the other. Three types of contraction crack are described. Type 1 occurs within the gravel aggradation of ac. 3 m OD terrace; type 2 penetrates this gravel and is filled with a complex of sediments, including primary, secondary and trough fillings; type 3 penetrates younger lacustrine sediments and gravels associated with Lake Sparks, the lake formed by the damming of Fenland by Late Devensian ice at the Wash. The networks are related to type 2 and type 3 cracks. The relation of permafrost periods to the stratigraphy and landscape development is described, together with the chronology. Periods of sand‐loess and cover sand deposition are identified. A period of permafrost degradation may be associated with change of climate and/or the development and proximity of Lake Sparks. A major period of permafrost in the area is correlated with the Weichselian Late Pleniglacial major permafrost event in the Netherlands (24 ka to 17 ka BP) and a similar major event in Poland (22 ka to 19/20 ka BP). This appears to be, broadly, the period leading up to and associated with the advance of the Late Devensian (Weichselian) ice in Britain and on the continen

ISSN:1045-6740    

DOI:10.1002/ppp.3430040402

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA rare observation of a slushflow that released on a low‐angle slope was made on 16 May 1992 in the West Karakol Valley, southern Kirgiz Range, Kirgizstan. The slushflow released on a short slope of 6° and travelled a distance of 140 m over a slope with a mean angle of 3° with a mean channel width of about 4 m. Total volume of snow and slush transported by the slide was more than 200 m3with an estimated mass of 200,000 kg. Estimated velocity of the flow was 5 ms−1. Meteorological conditions preceding the event included heavy cloud cover and clear skies with warm temperatures. Rain fell for about six hours during the day before the event. Mixed rain and snow precipitation continued through the preceding night accompanied by steady high winds. The day of the release was warm with overcast skies and light rain. The snowpack was generally saturated to the surface at the time of the release, and water was flowing over the snow surface in the path of the slus

ISSN:1045-6740    

DOI:10.1002/ppp.3430040403

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractNous présentons l'analyse des résultats d'une étude expérimentale réalisée à l'aide des méthodes de spectroscopie diélectrique et de conversion électroacoustique. Ces expériences ont été effectuées sur des modèles de sable de quartz poreux saturé de solutions de concentration différente, à contenu ionique différent et gelé. Ces expériences ont permis d'établir les particularitées communes à la cinétique de congélation de sols salins. Il s'est avéré que la concentration limite des solutions saturantes dans les pores est d'environ 10−2mole 1−1. Cette limite correspond à la concentration a partir de laquelle la cinétique de congélation de sols salins diffère substantiellement de celle de sols non‐salins. Pour des concentrations de solutions dans les pores qui sont>10−2mole 1−1, le sable gelé conserve sa perméabilité (dans les pores et capillaires) jusqu'à des temperatures très basses. On démontre que lors du processus de congélation, le changement du contenu de la phase liquide s'effectue en měme temps que le degré de discrétisation (ségrégation et fractionation) volumique et la mobilité des ions augmentent. La modification d'un sol gelé fortement salin (>10−1mole 1−1) en un sol gelé non‐salin s'effectue à des températures environ 10 K plus basses que l

ISSN:1045-6740    

DOI:10.1002/ppp.3430040404

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractAnalysis of open‐system pingo ice in Adventdalen, Spitsbergen, reveals its growth process. Ice and water sampled from edge to centre and from top to bottom of open‐system pingos are analysed. The results suggest that, after the underground water supply stopped, pingo ice extended downward. This downward extension seems to lower the level of underground water. The growth of open‐system pingo ice is supported by injecting and/or segregating ice originated from underground water. Sea level and climate changes probably influence the underground water level. This is especially the case for pingos formed on the coastal

ISSN:1045-6740    

DOI:10.1002/ppp.3430040405

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractPerennially frozen lacustrine deposits in the Bolivian Altiplano are discussed. They are situated between 21°38′S and 23°13′S at an elevation of 4117–4730 m ASL. It is hypothesized that these ice‐rich lacustrine deposits formed as the result of subaquatic freezing of sediments in the Late Pleistocene to Early Holocene. The permafrost bodies are represented today by flat‐topped ridges and mounds which are the remnants of the original lake plains destroyed by thermokars

ISSN:1045-6740    

DOI:10.1002/ppp.3430040406

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:1045-6740    

DOI:10.1002/ppp.3430040401

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY