LIDAR-analys av flygsanddyner i Västerbottens inland : Har dynmorfologi bildad under tidigare interstadialer bevarats i landskapet?

• Main Author: Bogren, Fredrik
• Format: Bachelor Thesis
• Language: Swedish
• Published: Umeå universitet, Institutionen för ekologi, miljö och geovetenskap 2015
• Subjects: LIDAR; digital elevation model (dem); aeolian sand dunes; till-covered; preserved morphology; digital höjdmodell (dem); flygsanddyner; moräntäckt; bevarad morfologi; Geology; Geologi; Physical Geography; Naturgeografi; Northern Sweden
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-104812

The aim of this study was to map the prevalence of aeolian sand dunes in Västerbotten, northern Sweden to find dunes formed during earlier deglaciation phases, which was then preserved in cold-based conditions during the youngest stadial of the Weichselian glaciation. These preserved dunes were expected to be covered by a layer of till and have a rather faint morphology compared to dunes formed during the Holocene. Consequently, high resolution LIDAR-derived images from the Swedish mapping, cadastral and land registration authority (Lantmäteriet) was used to detect the dunes throughout an area covering most of Västerbotten, above the highest coastline and below the mountain range. The analysis resulted in several new findings of aeolian dunes compared to the findings in the quaternary soil map created by the Geological Survey of Sweden. Despite the fact some of the dunes at the LIDAR-derived image had a strange faint appearance, it was quickly evident during the fieldwork that the aeolian sand was not covered by till on any of the dunes visited. The common view during the last decades has been that cold-based ice will not erode or alter the morphology of the landscape beneath the ice. However, this study suggests that hypothesis may not be entirely correct, and therefore it can be hard to use geomorphological implications to reconstruct past glacial environments. Thus, it can be concluded that even under cold-based conditions, preservation of aeolian sand dunes in Västerbotten is probably not very common.