摘要:

ABSTRACTThe northernmost part of Scandinavia, the Va- ranger peninsula, belongs to the Subarctic zone. It is possible to observe there the occurrence of both active and inactive periglacial phenomena at the same height above sea level. The area is picked out as being transitional between the active periglaciai zone of the Arctic, and the fossilised periglacial zone of Central Europe. In comparison with Spitsbergen. Varanger only exhibits half the active, high Arctic periglacial processes.

ISSN:0435-3676    

DOI:10.1080/04353676.1979.11879976

出版商:Taylor&Francis    

年代:1979

数据来源: Taylor

摘要:

ABSTRACTMoraine systems fronting 25 glaciers in the Svartisen, Okstindan, and Saltfjell areas were studied. Samples for C14dating were obtained from 7 moraines, and lichenometric data were gathered from about 125 moraines. The earliest C14dated maxima were from 2800 C14yr B.P., but there was evidence that a few glaciers reached relatively advanced positions prior to this: early advances may have occurred about 6000 and 4500 C14yr B.P. Radiocarbon dates suggested that glaciers reached Holocene maxima around 2800, 1900. 1500–1300, 1100 and 600 C14yr. B P. The majority of the moraines dated by lichenometry were from the 14th century or later. During this interval spanning 600 years glaciers advanced frequently, but no single period was marked by an outstandingly large number of well-preserved moraines.

ISSN:0435-3676    

DOI:10.1080/04353676.1979.11879977

出版商:Taylor&Francis    

年代:1979

数据来源: Taylor

摘要:

ABSTRACTStratigraphic evidence is presented for the commencement of solifluction at a site 850 m a.s.l. during the Early Subboreal Chronozone. at ca. 5500 years B.P. It is possible that this process was initiated as the result of a climatic deterioration, in which case the site examined provides one of only two examples of14C-dated stratigraphic evidence currently available for such an event occurring at around this time in the mountains of Scandinavia.

ISSN:0435-3676    

DOI:10.1080/04353676.1979.11879978

出版商:Taylor&Francis    

年代:1979

数据来源: Taylor

摘要:

ABSTRACTMoraine ridges which have a great morphological resemblance to De Geer moraines have been found in Bunnerfjällen in south-west Jämtland. Two deglaciation models are presented which form the basis for a discussion of the environment in which the ridges were formed. The moraines are assumed to have been deposited by an ice that was damming a small, shallow, proglacial lake and may be closely related to De Geer moraines.

ISSN:0435-3676    

DOI:10.1080/04353676.1979.11879979

出版商:Taylor&Francis    

年代:1979

数据来源: Taylor

ISSN:0435-3676    

DOI:10.1080/04353676.1979.11879980

出版商:Taylor&Francis    

年代:1979

数据来源: Taylor

摘要:

ABSTRACTThe present day limits of Grubengletscher are described and related to known positions since 1934 and the supply of debris to the glacier surfaces. Retreat and downwasting of part of the glacier system in this century has apparently resulted in the formation of a spatulate or valley rock glacier as a separate entity from the main glacier. One section of the main glacier, although still actively flowing, has a considerable debris load and bears a distinct surface resemblance to a‘typical’rock glacier. The relationship of four elements of the debris- glacier system shows the way in which debris accumulation, when allied to certain types of glacier mass balance behaviour, can result in the formation of ice-cored rock glaciers. Other rock glaciers in the vicinity of Grubengletscher are also described.

ISSN:0435-3676    

DOI:10.1080/04353676.1979.11879981

出版商:Taylor&Francis    

年代:1979

数据来源: Taylor

摘要:

ABSTRACTThe spring run-off was forecast by evaluating the snow pack, the precipitation, the evaporation and the change in ground water and soil moisture during the melt season. The snow pack is the most important run-off factor. A snow map has been made up from a number of measuring points to serve as“ground truth”(key) in order to simplify the methods of assessing the snow pack, i.e. measuring the snow depth and determining the snow density along some suitable profiles. The height above sea level has to be determined for every observation point. The results obtained deviated at the most 10% from results gained by the snow map. The run-off forecasts proved between 2% too low and 20% too high for three investigation areas during two subsequent years. Aerial photographs of the investigation area have suggested a connection between the percentage of snow covered ground and the remaining run-off during two years.

ISSN:0435-3676    

DOI:10.1080/04353676.1979.11879982

出版商:Taylor&Francis    

年代:1979

数据来源: Taylor

摘要:

AbstractA small recirculating laboratory flume was used to study the transportation and deposition of coarse silt (D50= 0.045 mm) under conditions of approximate transport equilibrium. Nineteen runs were made with a range of Froude numbers between 0.07 and 1.23 and with total sediment concentrations as high as 393.000 mg/1. Depths of flow (as much as 10 cm or one half of channel width) were adjusted by means of a sidewall correction for subsequent calculations of Reynolds number, Froude number, and stream power.Ripple bed forms in the lower regime of flow developed at Froude numbers less than 0.75 approximately. Plane bed and standing wave or antidune bed forms developed at Froude numbers in excess of 1.0. Flat symmetrical ripples, irregular low ripples, and plane bed forms characterized the transition between the lower and upper regimes of flow. The transition occurred at a stream power value of approximately 2 g.cm.-1'.s-1. There was, however, some overlap in the stability fields of the several types of bed forms.Lenticular, tabular, and irregular units of crosslamination were deposited, in addition to parallel (plane) lamination, in the lower regime of flow. Parallel (plane) lamination, undulóse lamination, and thin units of cross-lamination were deposited in the transitional regime. The upper regime of flow was characterized primarily by parallel and undulose lamination. The cross-laminated units deposited by ripple migration in the lower regime of flow had an average length of about 0.7 x the ripple wave length and an average maximum thickness of 0.8 x ripple height. The silt behaved essentially as a cohesionless material.

ISSN:0435-3676    

DOI:10.1080/04353676.1979.11879983

出版商:Taylor&Francis    

年代:1979

数据来源: Taylor

摘要:

ABSTRACTStudies of the morphological changes exhibited by an Alpine proglacial valley-train over a six-year period of glacier advance have provided quantitative evidence of initial degradation and subsequent extensive aggradation, the latteraver- aging ca. 1300m3/yr. Valley-train gradients have been consistently steepened as maximum amounts of coarse debris accumulated on the proximal slope of the valley-train, while localized aggradation has caused progressive burial by outwash deposits of a former terminal moraine. Aggradation of fluviogla- cial sediments occurred as sediment loads exceeded the competence of the meltwater streams; the streams created an increasingly dense network of braided courses in order to accommodate the relative increase in sediment loads, a stream pattern that was encouraged by the series of coarse, unstable bank deposits, frequent and large variations in meltwater discharge. a sudden downstream decrease in gradient, and the absence of vegetation. Mean channel sinuosity, bar shape, and log-normal size frequency distribution of mid-channel bars remained the same from year to year, while the actual size of bars exhibited a marked decrease; the mean orientation of mid-channel bars moved systematically westwards by over 10 degrees, as deposition of proximal outwash was extended eastwards along the ice-marginal zone. A simple model is proposed to illustrate the possibility of net aggradation and degradation occurring during a glacier advance and/or retreat, according to the balance between meltwater competence and sediment loads within the proglacial zone.

ISSN:0435-3676    

DOI:10.1080/04353676.1979.11879984

出版商:Taylor&Francis    

年代:1979

数据来源: Taylor

摘要:

AbstractThe existence of groups of highly intercorrelated variables among the large number of parameters widely usedfor quantifying drainage basin morphology suggests the possibility of reducing them to fewer dimensions. Through principal axis factor analysis of 37 morphometric properties of 52 third-order basins in the Udi-Awgu cuesta of south-eastern Nigeria, six factors identified as measures of intensity of dissection, stream network size, relief, shape, link length ratio and bifurcation ratio, are found to account for 92 per cent of the variance in the data. The factor-defining variables are total drainage density, total stream length, relief ratio, lemniscate ratio, link length ratio and bifurcation ratio respectively.These findings are essentially similar to those obtained for the third-order basins of southern Uganda, western U.S.A., southern Indiana, Barbados and Tobago. These studies suggest that, irrespective of differences in climate, lithology and vegetation cover, the morphology of drainage basins may be adequately quantified by measurement and analysis of these six variables which thus constitute the parameters of the reduced rank model of the morphology of drainage basins. Explanations are offered for the orthogonality of these dimensions, and their geomorphic and hydrologic importance are briefly reviewed.The identification of these underlying dimensions will not only simplify future morphometric work but also provide criteria for an objective multi-dimensional morphological classification of drainage basins.

ISSN:0435-3676    

DOI:10.1080/04353676.1979.11879985

出版商:Taylor&Francis    

年代:1979

数据来源: Taylor