Factors determining the impact of glacial erosion on shield surfaces
2013 (English)In: 8th International Conference (AIG) on Geomorphology: Abstracts Volume, 2013, 272-272 p.Conference paper, Abstract (Refereed)
The erosional effect of ice sheets on shield bedrock surfaces has been debated for many decades. Whilst there seems to be agreement that ice sheet erosion of the bedrock landforms was generally modest, and that many preglacial landscape elements remain, we need to know which factors influence ice sheet dynamics and erosional impact on the shield. Using GIS-analysis and field observations, combined with cosmogenic exposure ages, we investigate areas with a similar ice cover history but with greatly different degrees of glacial erosional impact. On two transects with an area of ~35 000km2 each across the shield, we examine why glacially eroded areas exist adjacent to areas of negligible glacial erosion. Firstly, a E-W transect, identifies two areas of exceptional glacial preservation, the Parkajoki area in Sweden and the so-called ice shed zone in Finland, each with large tors and deep saprolite covers. Secondly a NW-SE transect, overlapping in the northern part with the first transect, includes areas of intense glacial streamlining, with bedrock areas stripped of loose material and barely any weathering remnants. For areas of negligible and advanced glacial erosion, we investigate geology, elevation, topography, hydrology and duration of ice cover in an attempt to identify factors leading to ice sheet erosion/preservation of the underlying shield landscape. We estimate the duration of ice cover from the known ice cover history. We use a single flow path and thereby use steady glaciological parameters. Our results point to glacial bedrock erosion of flat shield surfaces in the range of tens of meters. Erosion only happens in areas where the ice is forced to flow around obstacles or into basins. These preglacial landscape properties are in turn determined by bedrock geology and long-term geomorphic and tectonic evolution. Consequently, a combination of bedrock type and topography determines ice sheet properties and thereby effects of ice erosion on shield surfaces.
Place, publisher, year, edition, pages
2013. 272-272 p.
Research subject Physical Geography
IdentifiersURN: urn:nbn:se:su:diva-96042OAI: oai:DiVA.org:su-96042DiVA: diva2:662855
8th International Conference (AIG) on Geomorphology, "Geomorphology and sustainability", Paris, August 27-31, 2013