Distribution of Glacial Landforms in Southern Norway in Relation to the Thermal Regime of the Last Continental Ice Sheet Author(s): Johan Ludvig Sollid and Leif Sorbel Source: Geografiska Annaler. Series A, Physical Geography, Vol. 76, No. 1/2 (1994), pp. 25-35 Published by: Blackwell Publishing on behalf of the Swedish Society for Anthropology and Geography Stable URL: http://www.jstor.org/stable/521317 Accessed: 10/06/2009 09:31 Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at http://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. 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Series A, Physical Geography. http://www.jstor.org DISTRIBUTION OF GLACIAL LANDFORMS IN SOUTHERN NORWAY IN RELATION TO THE THERMAL REGIME OF THE LAST CONTINENTAL ICE SHEET BY JOHAN LUDVIG SOLLID and LEIF S0RBEL Department of Physical Geography, University of Oslo, Oslo, Norway Sollid, J. L. and S0rbel, L. 1994:Distribution of glacial land- mountains with gentler relief. While the western forms in southern Norway in relation to the thermal regime areas were situated near the margin of the Scan- of the last continentalice sheet. Geogr.Ann. 76 A (1-2): 25- 35. dinavian ice sheet during the Weichselian maxi- mum, the eastern areas, situated near the ice di- ABSTRACT.The zonation of morainesand meltwaterland- were covered thick ice. forms in southern Norway indicates that the ice sheet was vide, by cold-based during the deglaciation of the central areas. Morainic and meltwater landforms in most of Flutes, drumlins,Rogen morainesand end morainesin these Scandinavia were formed during the last part of central areas most probably predate the late Weichselian. the Weichselian glaciation. Therefore, the regional There is also a verticalzonation of landformswhich indicate distribution of these landforms can be used to ana- that the highest areas became cold-based at an early stage during the last glaciation. These higher areas are charac- lyze the extent and dynamics of the ice sheet dur- terized by blockfields and other weathering phenomena, ing this period. However, in some interior areas and no tracesof glaciationexcept meltwaterchannels and er- like the central parts of southern Norway, many ratic boulders. Later the cold-based zone of the glacier ex- morainic and meltwater landforms date pandedboth downwardsto lower partsof the terrainand out- probably wards to areas further away from the culmination zone. In from older periods (Sollid and S0rbel, 1982, 1984, these areas the glacier stayed cold-based throughoutthe de- 1988). Similiar evidence is found in central and glaciation period. Flutes, drumlinsand end moraines were northern Sweden (Lagerback, 1988a, 1988b; fossilized beneath cold-based while moraines ice, Rogen Rhode, 1988; Kleman and Kle- were formed by ice movement in warm-basedpatches with Borgstr6m, 1990; trappedwater beneath a glacier that was otherwise frozen to man et al. 1992, Kleman, 1992). the ground. In more distal areas of southern Norwaythe ice sheet was warm-based, and glacial landformstherefore di- rectly reflect the course of deglaciation. Regional distribution of glacial landforms The regional distribution of some types of glacial Introduction landforms in southern Norway is discussed below. This paper reviews the distributional pattern of These landforms include ice-marginal deposits morainic and meltwater landforms in southern (end moraines and ice-marginal deltas), drum- Norway (Fig. 1), and relates this pattern to the linoid forms (drumlins and flutes), Rogen morai- thermal regime of the Scandinavian ice sheet dur- nes, eskers, and marginal meltwater channels. ing the last part of the Weichselian glaciation. The The many ice-marginal deposits in southern Nor- following outline of the distributional pattern is way are part of large end-moraine systems that can mainly based on overview mapping of geomor- be traced more or less continuously over long dis- phology and Quaternary geology carried out by tances (Fig. 2). These moraine systems can in most the Department of Physical Geography, Univer- cases be correlated to climatic conditions that sity of Oslo (Sollid and S0rbel, 1977, 1982, 1985; existed at the time of their formation, such as the Sollid and Torp, 1984; Sollid and Kristiansen, Younger Dryas climatic deterioration. The inner- 1982, 1984; Kristiansen and Sollid, 1985, 1988; Sol- most end moraines from which it is possible to re- lid and Trollvik, 1991). construct a continuous glacier margin are found in The western part of southern Norway is charac- the Dovrefjell area and at the heads of the large terized by fjords and areas of alpine relief, while western fjords. These moraines were deposited the central and eastern parts have valleys and during the Preboreal. As to the general extent of Geografiska Annaler ? 76 A (1994) * 1-2 25 J.L. SOLLIDAND L. S0RBEL 10? 200 300 70 650 65 60< 60 55a \ /, I 55 /, Fig. 1. Key map of the investi- gated area in southern Norway. \\ 0 1~ 500 km Framed area corresponds to later figures showing the dis- tribution of different glacial 10? east 200 30? landforms. the Scandinavian ice sheet in different phases of ernmost Norway consist of exposed bedrock, and Weichsel, cf. Andersen (1981). have little surficial material available to form Some large end moraines also exist in the cen- drumlins and flutes. tral areas close to the culmination zone of the ice Rogen moraines are ridges with their long axis sheet, like on the mountain of S01n (Fig. 2). These perpendicular to the ice-movement direction; the moraines predate the deglaciation period, and ridges are usually 100-200 metres long and 10-20 they are probably not related to one singel glacial metres high, they are generally located in shallow advance. End moraines older than the last deglaci- terrain depressions, and they always occur like a ation are also reported from Sweden (Kleman, field of several individual moraine ridges at each 1992). location (Fig. 4). Their mode of formation is still a Drumlinoid forms include all kinds of stream- subject of controversy (Lundquist, 1969, 1989; lined moraine ridges formed by basal ice move- Shaw, 1979; Sollid and S0rbel, 1984; Bouchard, ment. The long axis of the ridges parallels the di- 1988; Aylsworth and Shilts, 1989; Fischer and rection of the ice movement at the time of their for- Shaw, 1991). It is clear, however, that Rogen mo- mation. raines are formed subglacially. Drumlinoid forms are common in most of south- Rogen moraine fields are found in the central ern Norway, except in regions with marked fjord parts of southern Norway, relatively close to the topography (Fig. 3). Otherwise their distribution culmination zone of the last ice sheet (Fig. 5). is not restricted to particular areas, but their den- They have not been found in coastal areas, nor in sity of distribution varies. This seems, to a certain places which have recently been uncovered by con- degree, to be related to the distribution of surficial temporary glaciers. deposits. Extensive areas of western and south- Eskers. Only a few eskers occur in or near coas- 26 Geografiska Annaler ?76 A (1994) ? 1-2 GLACIALLANDFORMS IN SOUTHERNNORWAY Fig. 2. Distribution of ice-marginaldeposits (end moraines Fig. 3. Distribution of drumlinoide forms in southern Nor- and ice-marginaldeltas) in southernNorway. D=Dovrefjell, way. 1=drumlins, 2=flutes. In addition, the mainposition of S=S0ln. the ice divide is markedon the figure. tal areas, but they are common in a broad zone Landscape zonation further inland. Relatively few, small eskers are Based upon the distributional pattern of the diffe- found in the central areas near the culmination rent landforms described above, southern Norway zone of the ice sheet (Fig. 6). can be divided into the following zones (Fig. 8): Lateral meltwater channels are most common in the central regions of southern Norway. Here they I This zone is characterized by ice-marginal de- often occur in large series, where several channels posits, with extensive end moraines deposited run more or less parallel to each other along a hill- mainly during the Younger Dryas and the Pre- side (Fig. 7). As our geomorphological overview boreal. In addition, drumlins and flutes are maps do not distinguish between different kinds of quite common, especially in the inner part of meltwater channels, the regional distribution of the zone. Most of the ice-marginal deposits lo- lateral meltwater channels is only generally cated below the marine limit consist of glacio- known. fluvial material transported to the ice margin in meltwater conduits. Some large eskers exist, but marginal meltwater channels are rare. Geografiska Annaler ?76 A (1994) * 1-2 27 J.L. SOLLIDAND L. SORBEL Fig. 4. Rogen morainesnear the lake Fullsenn,Valdres, southern Norway. Scale of air photo, 1:35000.