摘要:

AbstractSeven bogs adjacent to Puolejokk in Padjelanta, Swedish Lappland, contain palsas either in groups as low winding ridges, or as large isolated oval-shaped hummocks well above the surface of the bogs. In midsummer 1963, trenches 2 m long, 30 cm wide, were excavated down to the tjäle across several palsas in each of the four largest bogs. The thawed dark brown to dark reddish brown peat of each palsa rested on a frozen core of gray sand or of till. By mid-summer 1967, the previously trenched palsas had caved in, collapsed, or sunk beneath the water of the bogs.Permanently frozen ground exists under better drained nonsorted polygon areas nearby, indicating a climate conducive for palsa maintenance, although the larger palsas may have reached a growth stage such that any slight disturbance might produce deterioration. Alternatively, larger undisturbed palsas may be collapsing in the wetter bogs due to water level changes.

ISSN:0435-3676    

DOI:10.1080/04353676.1969.11879793

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractSandy Glacier, occupying the head of a 3 km by 1 km cirque valley, is composed of a unique alternation of ice layers and sand layers. The sand was apparently brought by occasional very strong winds from Onyx River outwash 5 km away and 1,200 m lower. Pits dug in the accumulation zone revealed 115–210 cm of firn and sand layers directly overlying glacier ice that also contains sand layers. It is believed that not long ago there was no cover of firn on any part of this glacier. Accumulation appears to have recommenced perhaps 2–3 decades before the present.

ISSN:0435-3676    

DOI:10.1080/04353676.1969.11879794

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

ISSN:0435-3676    

DOI:10.1080/04353676.1969.11879795

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractTemperature data from two snowpatches in the Canadian Rocky Mountains are presented and discussed with respect to their geomorphological significance. While the data represent the summer period only, they show that the presence of snowpatches influences mountain wall temperature conditions to the extent that diurnal freezing and thawing occurs occasionally. Shattered bedrock on the mountain walls indicates that active physical weathering has occurred. An under-cutting or notch at the break in slope between the mountain wall and a talus accumulation indicates that the weathering is most concentrated in this location. This break in slope is often the site of late-lying snowpatches. The shattered bedrock, the notch and the temperature data suggest that the presence of snowpatches is of considerable geomorphic significance in the high mountain environment.

ISSN:0435-3676    

DOI:10.1080/04353676.1969.11879796

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractStriped ground, terraced slopes, gliding blocks and stone banked lobes, the latter formed from material of an old wall constructed prior to 1815, are described from between 670 and 750 m altitude in the Rhinog Mountains, North Wales. It is suggested that the formation of these features may be attributed to gelifluction and cryoturbation processes in the“Little Ice Age”which occurred between about 1550 and 1750 A.D. and that other patterned ground features of similar scale on British mountains may owe their origin to the same period.

ISSN:0435-3676    

DOI:10.1080/04353676.1969.11879797

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractIn order to evaluate the importance of differential transport velocities as a factor in sediment sorting by size and shape, transport velocities of individual size fractions in heterogeneous size mixtures of spherical glass beads and natural material were determined for different transport rates.Particle transport velocities in material of mixed sizes are shown to be significantly influenced by size and shape of the constituent particles. Maximum velocities occur in the intermediate size fractions for spherical glass beads and are displaced toward coarser fractions for natural material. Relative difference in transport velocities between size fractions may increase with increase in transport rate. The effect of particle shape on transport velocity decreases with increase in rate of transport. The results are tentatively projected to natural conditions, and novel solutions to some problems of sediment sorting are suggested. Particle settling velocity is found to be a well defined function of geometric particle shape, while transport velocity in bed contact motion correlates only poorly with the same shape index.

ISSN:0435-3676    

DOI:10.1080/04353676.1969.11879798

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractThe Peak District of Derbyshire, England, is a moorland region of high and increasing soil-erosion potential. Samples from a variety of soils developed in the area were tested under simulated rainfall to assess their relative erodibility. Results of tests permitted estimates of annual soil-loss under specified conditions, which ranged from near zero to 160 tons/acre year. Using a threshold value of 11 tons/acre year, 58% of the soils were deemed liable to serious erosion. Behaviour of samples under simulated rainfall is described, and largely explained by variations in aggregation characteristics. Results of tests indicate that podzolic soils are more erodible than brown earths, woodland soils more erodible than grassland soils,“gritstone”soils more erodible than“limestone”soils, and B horizon soils more erodible than A horizon soils. On the basis of test results a general hypothesis explaining patterns of soil erodibility in the region is advanced.

ISSN:0435-3676    

DOI:10.1080/04353676.1969.11879799

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractCalculations of direct beam radiation are combined with diffuse radiation measurements to produce maps of the global radiation for all slope facets of a forested hill at latitude 45°. Net radiation is derived from the global radiation calculations to give the radiant heat energy available for evapotranspiration and the sensible heating of air and soil on north and south slopes. Measurements of weekly evapotranspiration, the seasonal regimes of soil moisture, snow accumulation and melt, and air and soil temperatures are presented for north-and south-facing slopes.The greatest slope differences in global radiation occur in the fall and winter, whereas in summer, variations due to exposure are minimal. Accumulative evapotranspiration over the growing season shows little difference between north and south slopes although substantial differences were noted before leaf development. Differential snow melt leads to complete snow removal from south slopes which is three weeks in advance of those facing north. As a result, north slope soils have stored 50% more water than their southern counterparts by early spring. Trend surface analysis shows that the spatial distribution of surface soil moisture is correlated with the cubic shape of the hill in early spring and that this pattern persists for at least three months. The greater consumption of available heat for evapotranspiration from north-facing sites results in lower air and soil temperatures than on south-facing ones.

ISSN:0435-3676    

DOI:10.1080/04353676.1969.11879800

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractThe diurnal variation of precipitation in Sweden is studied with the aid of (a) records from 39 stations which have performed measurements in the morning and evening, (b) records from three pluviograph stations. Mainly the“classical”types of the diurnal variation occur, viz. in summer most of the precipitation falls during the day over land and during the night over the sea and in winter the difference between day and night precipitation is less, often with a night excess over the land. An important exception is the north-western mountain range, where a marked day maximum occurs during winter. This may be due to the proximity to the Atlantic.

ISSN:0435-3676    

DOI:10.1080/04353676.1969.11879801

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor