摘要:

ABSTRACTA mathematical wave erosional model was used to investigate the effects of seven late Holocene sea level fluctuations, on the development of rock coasts. Each run was repeated for different combinations of sea level, tidal range, wave intensity and rock resistance. The results suggest that on a uniform Earth, wide and gently sloping intertidal shore platforms would develop in high latitudes which were formerly ice covered. Narrow and steep platforms would form in areas which were peripheral to the ice, and in the collapsed forebulge regions. Much further from the ice, the intertidal platforms would tend to range from moderately gentle and wide, to very gentle and wide. Some of the model predictions were found to be broadly consistent with the limited field evidence presently available. In many cases, however, platform morphology can be at least partly explained by climate, tidal range, wave intensity, and rock resistance, without recourse to Holocene changes of sea level.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880154

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

ABSTRACTBeach forms associated with the retreat of Cook Glacier, between 1975 and 1982 are compared with those found on polar beaches. The presence of certain characteristics but the absence of many others diagnostic of polar beaches distinguishes Cook beach as a sub-polar feature. Evidence from Neoglacial moraines and raised beach deposits indicates that former positions of Cook Glacier have controlled beach location but that the preservation of Neoglacial beaches depends on isostatic recovery outpacing beach reworking. At Cook beach the occurrence of glacial till overlying beach deposits adjacent to beach deposits overlying glacial till indicates the type of complex stratigraphy that may be present in Quaternary deposits from tidewater glacier environments.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880155

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

ABSTRACTBecause boulder beaches and rubble coastal-protection structures have environmental and compositional similarities, beach-boulder movement is examined in the light of engineering studies of protection-structure stability. On a studied boulder beach, sediment transport occurred during 11 storms over a period of 2 years. Wave conditions from these 11 storms are used in two no-damage design formulae in an attempt to mathematically predict boulder movement. The design formulae over-predict the movement threshold of smaller sized beach sediment and under-predict the movement threshold of the larger sediment, however the Hedar formula (developed for low-angle protection structures) yielded the more realistic prediction.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880156

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

ABSTRACTAeolian transport rates from the shores of the Black Sea, the Baltic, and the Sea of Okhotsk are reported. At the Black Sea, the prevailing wind direction is towards the sea and causes transportation of sediments from the shore to the sea. The sandy shores of the Baltic and the Sea of Okhotsk are dominated by onshore winds, therefore sand is mostly transported there from the beaches inland. Transportation volume depends on the velocities and duration of the winds, the sand humidity, the density of vegetation and the unevenness of the relief of the beach.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880157

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

ABSTRACTMy work in the team on Prins Oscars Land was to study the present-day geomorphological processes and their effects, in an area of crystalline rocks and rolling landforms, with glacial forms located mainly along the fiords. Most of the work was done on the eastern side of Rijpfjorden. The various processes are discussed in separate sections. Particular interest is given to frost weathering, which is slow at present, but has probably been more important in some past period, to judge from well-developed block fields and from sequences of raised beaches produced from solid rock by frost weathering combined with marine processes. In a special section patterned ground and mass movement, mainly of tundra polygons and rock glaciers, are presented.Main attention is devoted to the marine processes, the most efficient processes in recent time, producing erosion forms in solid rock and wide fields of raised beaches. Forms related to marine processes are much better developed in the outer parts of the fiords, while the inner parts have almost unchanged glacial forms, particularly in solid rock. The strong morphological differences between north and south may indicate a clear difference in the time of deglaciation. On the peninsulas of the area there is a series of talus cones eroded by the sea. As this may indicate a present transgression, an appendix is added in which similar forms from all Svalbard are examined. The frequency of these is high and well-distributed, and most probably indicates a present land depression. Some archaeological data give a similar picture.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880158

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

ABSTRACTA first attempt at applying lichenometry to a geomorphological study of slopes on Spitsbergen is presented. Use of this method reveals evidence for the influence of the“Little Ice Age”(the 70 B.P. and probably 500–300 B.P. stages) on construction of debris cones and rockfall talus. Rock glaciers originated during an earlier Neoglacial period (most likely 3500–2000 B.P.). Lichenometry connected with estimates of rock debris volumes calculated according to Rapp's method allow tentative evaluations of the rates of late Holocene rock wall retreat amounting to 0.0 to 0.7 mm/yr. The main factors governing rates of retreat are the pattern of glacial dynamics and secondarily the rock type and the joint spacing. However, because there are insufficient control points to establish a growth curve forRhizocarpon geographicums.l. in Svalbard, chronological control is rather crude presently. Nevertheless, these results are significant in so far as they cross-check estimates proposed by Rapp utilizing other methods in central Spitsbergen and northern Scandinavia.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880159

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

ABSTRACTThe paper describes a catastrophic landslide (rock avalanche or sturzstrom) of Holocene age in Verkilsdalen, Rondane, southern Norway. The feature with a rock debris volume of about 20×106m3, represents one of the largest landslides in northern Europe. The process of debris movement appears to have been related to an initial phase of sliding followed by a phase of rapid flowage. Flowage seems to have been induced by the impact of the rapidly sliding mass against the lower valley-side slopes. This also resulted in the production of a complex network of bedrock fissures and in the displacement of several sections of hillside. During flow, the fastest moving material was propelled in front of the leading edge of the moving mass and was deposited as a relatively fine-grained debris apron. It is proposed that the Verkilsdalen sturzstrom took place principally by momentum transfer through block collision (cohensionless grain flow). This process of formation contrasts with those suggested for many other catastrophic landslides where air layer lubrication and fluidisation due to air entrapment have often been invoked as agencies of rapid debris movement.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880160

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

ABSTRACTThe intensity of frost shattering and the amount and type of debris produced from quartzite, granulite andrapakivigranite samples were studied with laboratory experiments. The experiments were run for 1103 temperature cycles from +15°C to -8°C. The amounts of debris ranged from 0.01 to 0.8 percentages of debris relative to dry weight of the original samples. Grain size of frost weathered material was mainly in sand and gravel fraction classes. Surface texture of quartz grains was studied with SEM. Shape of the grains was irregular and their edges were sharp. Many of the surfaces were rather smooth. Irregular conchoidal fractures are also characteristic. Very often the surfaces were covered by very small, flat fragments of quartz. Some opened microfissures were also found in the grains. The Finnish rocks seem to be very resistant to frost weathering and postglacial frost shattering has had rather limited importance in landform formation in Finland.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880161

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

ABSTRACTNearest-neighbour analysis can be applied to polygonal ground patterns to give a quantitative evaluation of the pattern. The nearest-neighbour statistic (R) indicates the degree to which an observation departs from an expected random pattern. The R-statistic is particularly useful in comparing patterns by highlighting differences that are not subjectively obvious. Because the nearest-neighbour technique eliminates the effect of scale, it can be used to compare a variety of patterns, including ice-wedge and desiccation polygons, lava cooling cracks, and tectonic tractures. Nearest-neighbour analysis can also be applied to the large-scale polygonal ground on Mars and other planetary bodies.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880162

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

ABSTRACTSalt weathering is now regarded as an important agent of rock disaggregation in deserts. This paper assesses the relative importance of two potential sources of stress associated with salt weathering, namely crystallisation pressure and volumetric expansion upon hydration, by comparing their ability to cause particle size changes in prepared aggregates of a shale. Two sets of replicate samples in the 2 to 16 mm size range were subjected to 200 24 hour cycles involving respectively conditions favourable to salt crystallisation alone, and to crystallisation followed by salt hydration. An additional set was exposed to 200 cycles of low and high relative humidity respectively but without salt. Crystallisation and salt hydration operating together were no more effective in the production of fines (material>2 mm) than crystallisation acting alone. However, a comparison of the pre- and post-test grain size distributions showed a greater internal transfer among existing grades for the crystallisation-hydration combination. Here hydration augmented crystallisation following the penetration of salt solutions along bedding planes. However, the overall contribution of hydration to salt weathering appears to be minor.

ISSN:0435-3676    

DOI:10.1080/04353676.1986.11880163

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor