NJG85-3-06
2005
Large-scale patterns of glacial streaming flow deduced from satellite imagery over Sør-Trøndelag, Norway
85
3
pp. 225-232
82-92394-21-4

Streamlining features such as drumlinoid forms and glacial striations, deduced from satellite imagery and maps over the Oppdal area, show distinct streamlining patterns that indicate the passage of a marked northeasterly-directed ice-stream across the area. This ice- flow had its origin in an icedome/ice-shed in the high plateaus of west central Norway. In the southern parts of the Oppdal area cold-bridges formed in the mountains of Skrymtheimen during an early phase of this glaciation/deglaciation and here the inland ice froze to the ground surface. Wet-bedded conduction appears to have existed in the lower plateau areas. The ice-flow divided into a western and an eastern branch, moving on both sides of the Skrymtheimen mountains. The westerly branch of this flow moved in a northeasterly direction traversing the deep valleys of Sunndalen and Gjevilvatnet. The relief amplitudes are here 800-1000 meters, and the ice flow must have been more than 1600 meters thick to overcome the prevailing relief. Throughout the phase of deglaciation in Scandinavia the thickness of the inland ice decreased and the influence of the topography (terrain amplitude) increased towards the end of glaciation, first in the western parts of the Oppdal area where deep valleys dominate and later in plateau areas in its eastern parts. Lateral moraines formed in some of the valleys, and were used to reconstruct a glacial surface extending in a westward direction. Tentatively this surface is correlated with an earlier described glacier surface in the Oppdal area formed during the YD (Younger Dryas) Chronozone. In the eastern parts of the Oppdal area this northeasterly ice-flow seems to have continued in the YD Chronozone. Deviations in the marked northeasterly directed streamlining features towards Drivdalen valley occur. This is to be expected as the remaining inland ice in the eastern parts of the Oppdal area served as source areas for ice-flows emanating from this plateau area into the valleys where valley glaciers formed and flowed in a westward direction. Streamlining features with a westerly trend were later developed in the most easterly parts of the Oppdal area and together with lateral moraines belong to a late phase of the YD Chronozone.

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