Glaciala och fluviala dalgångar i södra Norge : Ett resultat av mesozoisk sprickbildning och kenozoisk erosion
2019
Eklöv Pettersson, Anna
The dramatic landscape of Norway has a long history of different events during the Phanerozoic. During the Caledonian orogeny, the basement became fractured, and during the warm climate in the Mesozoic, the fractures became deeply weathered. These fracture systems later became eroded, forming the main structures for valleys. The landscape today is characterized by an elevated plateau with deeply incised valleys. Several theories discuss when and how the landscape became elevated. The main theory for this suggests uplift events of the plateau during the Tertiary. The uplifts resulted in a later elevated landscape with erosional plateaux in different distinct levels. This often referred to as the Palaeic relief. The uplift events also followed formation of incised fluvial valleys. During the Quaternary, glaciers partly reshaped these valleys. This study aims to investigate the shape of these valleys, and how much they have been reshaped during the glaciations. The study further aims to investigates if the identified shapes within the valleys can be connected to pre-glacial landforms. To investigate this, satellite images and topographic maps have been studied. A digital terrain model (10 m resolution) were used to create topographic cross sections across eight valleys in southern Norway. This study identifies possible pre-glacial forms and fluvial generations within five of the investigated valleys. Three of the valleys show a gradual transition from a broad, glacial, U-shape near the coast to become a narrower, V-shaped, fluvial valley further inland. The analysis also shows that the joints and fractures affect the width of the valleys which has affected the amount of glacial erosion. The results of this study clearly show that old fluvial valley remains is common, even within these major glacial valleys of southern Norway.
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