High-resolution LiDAR mapping of glacial landforms and ice stream lobes in Finland

Newly available high resolution airborne LiDAR (Light Detection And Ranging) technology is generating unprecedented next-generation imagery of Earth surface features. LiDAR datasets are being employed by the Geological Survey of Finland (GTK) as part of a new national geological initiative (Glacier Dynamic database: GDdatabase) to rapidly and cost-effectively map glacial landforms and sediments left by the last (Late Weichselian) Fennoscandian Ice Sheet (FIS). There is a high demand for such data in hydrogeological, geoengineering and mineral exploration projects and also for the identification of glacial landforms that provide key information regarding ice sheet rheology, growth and decay. An important step forward with this new technique is the recognition of paleoice stream corridors with fast flowing ice (> 3 km yr-1 based on modern ice sheets), surrounded by stagnant or sluggish-flowing ice. Precise geomorphic criteria are now available for recognition of paleo-ice streams, based on the elongation of subglacial streamlined bedforms and the presence of megascale glacial lineations. Flow sets of drumlins and megascale glacial lineations can now be mapped in high resolution using LiDAR and are now seen as genetically related forms in a continuum that records increasing ice flow velocity and the creation of a low friction bed. This paper briefly outlines the nature of the GDdatabase and the methodology behind its construction and provides examples of principal bedform types that record the dynamic interplay of paleo-ice stream lobes in the Finnish sector of the last FIS.