摘要:

AbstractA microstructural model of thermorheological processes during the freezing of fine‐grained soils is described. Using electron microscopy and X‐ray diffractometry, the changes due to freezing in the microstructures of kaolin, bentonite and askangel were experimentally studied. Curves of aggregate distribution and pore size for different freezing periods are presented. It is shown that there is good agreement between experimental results and theoretical hypothe

ISSN:1045-6740    

DOI:10.1002/ppp.3430030102

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractA solifluction meter that measures soil movements at eight levels in the active layer is described. Anchored in permafrost, the meter transforms mechanical movement of wooden blocks attached to flexible racks into changes in the electrical resistance of potentiometers. Solifluction can be monitored continuously with a data‐logger or manually at intervals when visiting field sites. Preliminary results from meters installed on the Fosheim Peninsula, Ellesmere Island, illustrate frost creep, with heave continuing at ground temperatures between −25°C and −30°C, and summer movements of the active layer in response to thaw consolidation and precip

ISSN:1045-6740    

DOI:10.1002/ppp.3430030103

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstractδ18O and δD values (% SMOW) were measured on 159 samples from the active layer and permafrost on peat plateaus and from the adjacent fen at sites about 50 km north of Tuchitua along the Robert Campbell Highway in southeastern Yukon Territory. The regression lines for the samples from the active layer and the permafrost were very similar, which suggests that they both contained mainly water from meteoric sources. The water samples from the fen produced results which gave a noticeably different regression line, so that it appears that the icy core of the peat plateaus is the result of downward penetration of precipitation into permafrost rather than freezing water migrating from the surrounding fen. These relationships appear to be constant throughout the study area, and there is no evidence of the ice being from an earlier, colder period. The precipitation in this area of the Yukon Territory shows a δD versus δ18O behaviour somewhat like that reported for Whitehorse in the literat

ISSN:1045-6740    

DOI:10.1002/ppp.3430030104

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractOver 1500 active rock glaciers have been identified in the Northern Tien Shan and the Djungar Ala Tau, Kazakhstan. Studies of the dynamics of six near‐glacier rock glaciers for 15–60 years show rates of movement in the main body of the rock glacier of 0.16–14.0 m/y. These also vary with time. Factors involved include climatic change, changes in ice content in the source area, flow of glacial meltwater through the rock glacier, changes in gradient of the underlying surface and changes in width of the valley through which it

ISSN:1045-6740    

DOI:10.1002/ppp.3430030105

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe micro‐relief on the surface of a rock glacier in the Dalton Range of the southwest Yukon provides evidence of processes occurring during and after development of the rock glacier. Ridges, mounds and flow lobes are interpreted as indicators of either the continuing deformation or reactivation of an ice‐core, solifluction of the surface deposits or changes in the internal hydrological system of the rock glacier. A glacial rather than periglacial origin for the ice core is prefer

ISSN:1045-6740    

DOI:10.1002/ppp.3430030106

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractL'enregistrement de la température et les mesures de l'humidité de la roche dans la glacière de Monlési ont révélé les conditions microclimatiques très particulières dans lesquelles s'effectue la gélivation de cette cavité souterraine. La très grande efficacité du gel est en apparente contradiction avec les quelques cycles de gels‐dégels annuels enregistrés. Cette intense gélivation des parois et du plafond de la glacière s'explique par le fait, que le gel agit dans une roche imbibée, voire saturée d'eau.Vu la rareté des glacières, leur impact sur l'évolution morphologique jurassienne est insignifinate. Cependant, au cours du Quaternaire, au début et à la fin des époques glaciaires, il n'est pas exclu que la plupart des cavités karstiques di Jura aient abrité une lentille de glcae. Si l'intensité de la gélivation fur celle que nous constatons aujourd'hui, ces dépressions karstiques s'avèrent ětre des formes mixtes, dues à la diss

ISSN:1045-6740    

DOI:10.1002/ppp.3430030107

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractPeriglacial phenomena and palaeobotany evidence of environmental changes are present in the Daqingshan area, northern China. This arid‐semiarid area is sensitive to climatic change. There were four climatic periods during the Holocene. During the Hypsithermal, the annual mean temperature was 1–2 °C higher than today. On the other hand, the annual mean temperature was 2.0–2.5 °C lower during recent glaciation and about 7 °C lower at the end of the Late Pleistocene. The fluctuation of vertical vegetation belts was about 200–600 m during the Holocene.Des phénomènes périglaciaires et des observations paléobotaniques démontrent l'existence de changements de l'environnement dans la région de Daqingshan, au nord de la Chine. Cette région aride ou semi‐aride est très sensible aux changements climatiques. Quatre périodes climatiques ont été reconnues pendant l'Holocène. Pendant l'Hypsithermal, la température moyenne annuelle était 1 á 2 °C plus élevée qu'aujourd'hui. D'autre part, la température moyenne annuelle était 2,0 a 2,5 °C plus basse pendant la glaciation récente et environ 7 °C plus élevée à la fin du Pléistocène. Les modifications des limites verticales de la végétation pendant l'Holocène ont été c

ISSN:1045-6740    

DOI:10.1002/ppp.3430030108

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractSmall‐scale, active patterned ground features (stripes and nets) are described for the first time from Ireland. Present‐day frost‐related processes are thought to be responsible for much of the surface morphology displayed by the pat

ISSN:1045-6740    

DOI:10.1002/ppp.3430030109

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

ISSN:1045-6740    

DOI:10.1002/ppp.3430030101

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY