Main Ice Sheet Research Articles

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.

Glaciology of the Ross Sea sector: Contributions from the Scott Polar Research Institute

Abstract Data from airborne radio-sounding programmes provide extensive information on the Ross Ice Shelf. The flow of ice from Marie Byrd Land glaciers is shown clearly. Study of the basal layers indicates the location of basal freezing and melting. The latter processes are controlled by oceanic circulation beneath the ice shelfand by bottom topography, rather than by conduction of heat. Basal melting appears sufficient to have a significant effect on the mass budget of the Antarctic continent. Ice discharge from Marie Byrd Land takes place mainly through ice streams formed in shallow depressions in the continental shelf below sea level. These streams slide on basal ice at the melting point, while ice rises between the streams are frozen to bedrock. Ice from the main inland ice sheet is discharged through trunk glaciers, while that entering the Dry Valleys is of local origin. Inward-trending valleys beneath the main ice sheet indicate an early extensive mountain glaciation preceding the formation of the main sheet.

Southeastward, Northward, and Westward Ice Movement in the Asbestos Area of Southern Quebec

Evidence of three major ice movements in the Asbestos area of southern Quebec is based exclusively on crag-and-tail glacial striations that have been measured on horizontal or subhorizontal bedrock surfaces. Cross-cutting glacial striations indicate early southeastward movement that was followed, as this portion of the ice sheet thinned by melting in late-glacial time, by a northward flow of the ice down the regional topography toward the valley of the St. Lawrence River, and finally, as the ice thinned further, was followed by a more local but prominent westward ice displacement down the local slope toward the valley of the St. Francis River. The ice mass that flowed northward and then westward is believed to have been separated from the main ice sheet and was left free to flow down the northward-sloping and, more locally, westward-sloping surfaces, causing the observed glacial abrasion.

Deglaciation and Isostasy in the Sukkertoppen Ice Cap Area, West Greenland

Three groups of landforms of deglaciation are analyzed, namely those associated with (1) the disappearance of Inland ice (main Greenland ice sheet), (2) the withdrawal of local Sukkertoppen ice, and (3) the changing of relative sea level. Consideration of their interrelationships in space and time allows a reconstruction of the process of deglaciation. There was an overall westerly movement of Inland ice across the area and this persisted during the early stages of deglaciation. Later stages of deglaciation reflect progressive downwasting with ice persisting in the troughs while adjacent plateau areas became free of ice. The highest marine limit is at 123 m and this incursion of the sea took place ca. 8,800 to 9,000 radiocarbon years BP. Local Sukkertoppen ice appears to have played an insignificant role during this main phase of deglaciation. Subsequently several Sukkertoppen outlet glaciers have advanced over marine deposits. The paper concludes with consideration of some wider implications. The importance of downwasting and meltwater activity during deglaciation is stressed. Also it is noted that isostatic recovery follows the Greenlandic pattern with high initial rates of uplift, apparently ceasing ca. 3,000 to 5,000 years BP. Unlike arctic Canada and Scandinavia where uplift has continued to the present day, the continued existence of a major ice sheet in Greenland is probably responsible for this recent stabilization. Finally, it is suggested that the last Inland ice sheet accomplished little erosion in the area compared to earlier ice sheets.

An Expedition to West Greenland, 1956

There are two regions of alpine country in the central and southern parts of West Gr enland and th y have attracted numerous expeditio s. The mo t int esting and extensive group of high, jagged peaks lies between Sukkertoppen and Holsteinsborg and this group reaches its climax inland of Kangamiut on the south side of the Sukkertoppen ice cap. Three great fjords break into the gneissic massif and the central one, Eternity Fjord (Evighedsfjord), splits into two branches the highland ice cap to which the island village of Sukkertoppen gives its name. The general height of the northern lobe of the Sukkertoppen ice cap is about 5000 feet and the mass of ice is separated from the main Greenland ice sheet by a deep and partly ice-filled trench, the Sarfortak valley. Between the southern edge of the northern branch of the ice cap and Evighedsfjord is a group of heavily glaciated peaks with a series of deeply incut valleys carrying quickly moving ice streams which have their sources on the ice cap. Among the alpine peaks are a number of high snowfields, the accumu? lation areas for other glaciers, some of which are tributary to the main ice streams, and others of which take an independent course towards the waters of the fjord which they may or may not meet. The culminating massif is Mount Atter, 2190 metres, and the peak is named after Michael Atter who met his death during the first Oxford University expedition to visit this region of West Greenland in 1935.* This expedition, led by H. O'B. Hayward, approached the ice cap from the north, by way of Sondre Stromfjord; they worked along the eastern edge of the ice and crossed the ice cap and, like the second expedition in 1936 led by Peter Mott, attempted to reach what they believed to be, and later proved to be, the highest mountain in the area. The peak was then called Mount Taterat and the group of peaks in the area the Taterat Berge, but the two expeditions were unable to approach near enough to the peak to make a serious attempt to climb it. The two expeditions carried out a great deal of exploration and mapping as has been reported in the Geographical Journal,2* 3 and their work also included a detailed glaciological programme. In 1938 another Oxford expedition, led by J. C. G. Sugden and P. G. Mott, approached the ice cap and the mountain from the south, by way of Evighedsfjord. Landing near the snout of the Taterat glacier the expedition set up their main camp at the junction of Survey glacier with the main ice stream. The party found that a route up the Taterat glacier was impracticable so they ascended to the southern edge of the ice cap by a western tributary, Igdlo glacier, at the head of which they estab? lished the second of their two glaciological stations. The extensive programme of work 4? 5 occupied most of a long season; however, an attempt was made to approach the south side of Mount Atter but was eventually abandoned. In 1956 a further expedition originally planned at Oxford and organized in the geography department of Bedford College, University of London, set out for Evigheds? fjord to continue the programme of glaciological work begun by the previous expedi? tions and also to attempt the ascent of Mount Atter from the south and to try to 1 Geogr. J. 88, 2 (1936), pp. 148-64. * Ibid.

Distribution of the Wisconsin Glacier in the Delaware Valley

INTRODUCTION The area discussed in this paper is shown on the Delaware Water Gap sheet, in eastern Pennsylvania, and part of the Easton sheet adjoining the Water Gap sheet on the south (Fig. 1). The outstanding topographic feature here is Kittatinny Mountain, which extends from northeast to southwest across the northern section (Fig. 2). Parallel to, and southeast of, the mountain extends the “Great Valley” (some ten miles wide). The Delaware River cuts across mountain and valley, entering the narrow highlands near Easton. The mountain is a critical portion of the area, for it stands between two districts of Wisconsin glaciation. MAIN ICE SHEET Ordinarily the extent of any continental glacier is considered to be determined by the position of its terminal moraine. In this region, the statement is commonly made that the terminal edge crossed the Delaware just below Belvedere, extending from that place westward and then northwestward to . . .