Rekonstruksjon av innlandsisen i Geiranger i yngre dryas og kvartærgeologisk kartlegging av Grinddalen

• Main Author: Horten, Trond
• Format: Master Thesis
• Language: Nynorsk
• Published: The University of Bergen 2018
• Subjects: anvendt kvartærgeologi; avsmelting; geologisk datering; innlandsis; kvartærgeologi; norge; https://data.ub.uio.no/realfagstermer/c030753; https://data.ub.uio.no/realfagstermer/c004887; https://data.ub.uio.no/realfagstermer/c009985; https://data.ub.uio.no/realfagstermer/c005935; https://data.ub.uio.no/realfagstermer/c001290; https://data.ub.uio.no/realfagstermer/c004255; 756199; Moraine Ridge; Ice Sheet
• Online Access: https://hdl.handle.net/1956/18114

The coastal areas of Sunnmøre has been subject to several previous studies, and they show that these areas were ice-free early in the deglaciation after LGM (last glacial maximum). Less research has been done on the deglaciation of the inner parts of Sunnmøre. The purpose of this thesis will be to contribute to a better understanding of the Late-Weichselian deglaciation in this area. The maximum extent of the Younger Dryas ice-sheet in Geiranger has been reconstructed based on lateral moraines. In addition to the mapping of the lateral moraines, a quaternary geological mapping of the valley Grinddalen, a valley situated south-east of the centre of Geiranger, has been made. Six prominent moraine ridges are found, and five of these are interpreted to be deposited by the inland ice during the maximum extent of the Younger Dryas ice. On one of these ridges, M3 at Møllsætrane, two 10Be exposure dates give an average age of 12,3 ± 0,5 ka, placing it to Younger Dryas. The sixth moraine ridge, M6 situated near Flydalssætra, is deposited during the deglaciation after Younger Dryas maximum, indicating that after the ice-margin rapidly calved back in the Geiranger fjord, the ice made a readvance to adjust to its new profile. During the Quaternary geological mapping of Grinddalen several interesting findings has been made. Two deposits from rock glaciers existing there in the time right after the ice disappeared from the valley and became inactive sometime around 14,6 ± 0,6 ka. The 10Be exposure dates from Hesjedalshaugen (1012 m.a.s.l.) and Grandehaugen (877 m.a.s.l.) give an average of 17,6 ± 0,7 ka for the time they were ice free, which implies that the higher areas in the region started to be ice free at this time, and the rock glaciers of Grinddalen must have formed sometime after this. In Grinddalen there is a moraine ridge 400 meters further into the valley from the Younger Dryas lateral moraine M3. This is deposited from the glacier in the main valley at an earlier stage than Younger Dryas, and can be correlated to ...