Nival Processes Research Articles

Observations on nivation and its geomorphological effects in mountains at high latitude (with Mt. Njulla Massif in Northern Sweden as example)

This paper presents the geomorphological role of snow patches In the remodeling of mountain slopes in the periglacial zone based on the results of morphological mapping of Mt. Njulla region, Northern Sweden. Effectiveness of nivation is strongly controlled by geological structure. On the Eastern slope, at the foot of the hillside, nivation processes play a critical role in the creation of numerous transverse nival hollows and cryoplanation terraces. On the western slope, meltwater, originating from snow patches, facilitates weathering and transportation of wastes downslope. Vegetation of the studied region is influenced by nivation. Effects of nivation are limited to reshaping of the relief.

NIVATION EVIDENCE FROM A NORTH-FACING SLOPE? GOLDEN GATE, EASTERN ORANGE FREE STATE

ABSTRACT Landforms most easily explained by recourse to nivation processes have been reported from the eastern Orange Free State and adjacent Lesotho. These landforms are usually associated with south-facing slopes above 1800 m altitude. A pair of landforms on a north-facing slope occur between 2100 and 2300 m. These are attributed to nivation action. The features consist of three ridges transverse to the slope whose components have undergone considerable disintegration in situ and rearrangement downslope. Blocks are absent from the upper third of the slope. The feature is attributed to frost shattering from a cliff, transport across a snow patch and accumulation as a series of three protalus ramparts. Nivation activity was therefore not confined to south-facing slopes.

Mass movements, nivation processes and climatic fluctuations in northern Scandinavian mountains

Climatic fluctuations during the twentieth century in northern Scandinavia and Spitsbergen may have influenced the frequency of rainfall-triggered mass movements such as debris flows, with a shorter recurrence interval during colder periods before c. 1920 and after c. 1960, and less frequent occurrence during the intervening warm period. However, precipitation data are contradictory regarding contrasts between warm and cold periods, and the recorded high number of debris flow events during later decades may also be a result of improved observations. Studies of nivation processes and snow cover distribution may provide additional information on climatic fluctuations. Examples are given of the use of nivation landforms as climatic indicators.

Freeze-Thaw Activity at Snowpatch Sites. A Progress Report of Studies in N. and S. Sweden

Within a study of nivation processes and landforms, the freeze-thaw activity is being measured at two sites in northern and southern Sweden. The aim is to test the hypothesis of active nivation occurring in the periglacial environment of northern Sweden, as opposed to the temperate south, in the present climate. Attempts will be made to relate the freeze-thaw activity to the operation of mass wasting processes at snowpatch sites. The report describes the study sites and the instrumentation used and concludes with some brief comments on initiated measurements.

A Comparative Study on Nivation Processes in Northern Swedish Lappland

A Comparative Study on Nivation Processes in Northern Swedish Lappland

A pioneer theory of nivation and glacigenic processes from 18th century

Thobias Gruber (*1744, +1806), a member of the expedition of the Czech Science Society to the Krkonoše range, two centuries ago, should be considered the founder of the physico-geographical research in the Sudeten Mountains, and a pioneer in geomorphological studies, mainly with respect to nivation and glacigenic modelling.

Freeze-Thaw Activity at Snowpatch Sites. A Progress Report of Studies in N. and S. Sweden

Within a study of nivation processes and landforms, the freeze-thaw activity is being measured at two sites in northern and southern Sweden. The aim is to test the hypothesis of active nivation occurring in the periglacial environment of northern Sweden, as opposed to the temperate south, in the present climate. Attempts will be made to relate the freeze-thaw activity to the operation of mass wasting processes at snowpatch sites. The report describes the study sites and the instrumentation used and concludes with some brief comments on initiated measurements.

Nivation landforms and snowpatch erosion on two massifs in the Northern Highlands of Scotland

Abstract On the An Teallach massif, nivation hollows have developed in Holocene deposits of niveo‐aeolian sand. During the spring melt, considerable quantities of reworked windblown sand and sediment eroded from the lateral scarps are transported by nival meltwater across the gentle (1–5°) treads of the hollows and deposited in small cones downslope. Other processes associated with nivation (accelerated chemical weathering and solifluction, intensive freeze‐thaw activity and snow‐creep transport) are unimportant under present conditions at this site. On Ben Wyvis, nivation landforms take the form of benches developed on frost‐weathered regolith. These benches are relict features; vegetation cover inhibits erosion by nival meltwater and other nivation processes appear to be inoperative. In sum, these observations suggest that present snowpatch erosion at the sites investigated is largely restricted to redistribution of cohesionless sediments by wash, and that even this process is of only local significance.

Nivation Hollows and Glacial Cirques in Söderåsen, Scania, South Sweden

The author leads a research project to test his theory of nival erosion and glacial protection of cirque forms in Scania (Rapp 1982 a and b), with comparative studies in Lappland and in middle and south Europe. The project will test the following postulates.The tundra periods in Scania, e.g. the Older and Younger Dryas had permafrost climate with strong effects of snow drifting by easterly and westerly winter storms. This is likely from observations of fossil ice-wedge casts on sandy plains in Scania, and from wind-polished bedrock and blocks with fluting marks, from easterly and westerly directions (G. Johnsson, Å. Mattson, H. Svensson). Large masses of snow were then trapped in the valleys of Söderåsen, forming nivation hollows and glacial cirques. This was also the case during the much longer tundra periods before the advances of the Quaternary main ice sheets over Scania. Small local glaciers and many nivation hollows were formed and grew, before the major ice advances. The canyons, cirques and nivation hollows were protected from destructive ice-sheet scour as their own, local ice-fill, made the large glacier slide over without much erosion (Rapp 1982). Our research program in Lappland will include winter and summer studies of contemporary nivation processes and resulting land forms at selected sites in the mountains of Abisko.

Are Terra rossa soils in Europe eolian deposits from Africa?

Abstract Recent studies of dust storms from drylands in Sahara and surroundings have shown that African soil dust in quantities of more than 100 million tons is blown westwards each summer over the Atlantic. The transport of eolian dust northwards across the Mediterranean is more irregular and smaller in amount than the Afro-atlantic dust plumes. Increasing evidence from studies of contemporary African eolian dust fallout in Israel and Italy, combined with observations in satellite images is the basis of the hypothesis that Terra rossa soils of south Europe may be the result of long-time eolian deposition of dust from Africa, and not created by residual weathering of the underlying bedrock. Possible locations to check the hypothesis of eolian origin are Terra rossa deposits in karst pockets of hard limestone in mountains of south Europe, particularly at elevations affected by Pleistocene nivation processes. A locality of this type in south Spain is described.

Nivation Hollows on the Southeast Slope of Mt. Onishi, Iide Mountains, Northeast Japan

Many well-developed nivation hollows, 100-200 meters in diameter, are found in two large hollows (glacial cirques?) on the southeast slope of Mt. Onishi, central part of the Iide Mountains. In this paper the writer observed geomorphological characteristics and soil profiles of the nivation hollows, monthly distributions of snow patches and zonations of plant communities in and around the hollows (cf. Fig. 3-7). He also attempted to explain nivation processes forming the hollows from the above-mentioned observations and the result of an experiment.Within a nivation hollow silt, sand and small gravel are transported mostly by rill-wash of rain water and snow meltwater. Average annual transport distances of gravel (∅1-5cm) have been known to range between 1.3 and 7.8cm from deformations of four experimental lines of painted gravel. Movements by solifluction and/or frost creep have not been observed from deformation patterns of these lines. Partial creeping of snow due to formation of crevasse in snow patch drags coarse materials, and it breaks down and shaves basement rocks. Both removal of sediment by rill-wash and denudation by creeping snow are relatively active on the core area of the hollow where lack of vegetation increases mobility of debris, while peripheral areas are protected against erosion by vegetation.However, weathered granitic bedrock under thin debris in the hollow suggests that mechanical denudation working is slight at present. Nivation hollows are thought to have been formed in the past when nivation was much more vigorous. Many relict nivation hollows covered with vegetation and those dissected by gullies are scattered in the Tide Mountains.