The inselberg landscape in Finnish Lapland: a morphological study based on the LiDAR data interpretation

• Published in: Bulletin of the Geological Society of Finland Vol. 90; no. 2; pp. 239 - 256
• Main Authors: Nenonen, K., Johansson, P., Sallasmaa, O., Sarala, P., Palmu, J.-P.
• Format: Journal Article
• Language: English
• Published: Geological Society of Finland 01.01.2018
• Subjects: erosion rates; Inselbergs; LiDAR technology; pre-glacial weathering; tor formations
• ISSN: 0367-5211; 1799-4632
• DOI: 10.17741/bgsf/90.2.008

An advanced method to study geomorphology of the well-known inselberg landscape in Finnish Lapland is introduced. Conventionally topographical maps and altitude reference produced from stereographic aerial photographs has been used. Now the LiDAR data has opened a new way to study geomorphology and terrain in detail. We applied the new methods in eastern Finnish Lapland from where seven inselbergs have been identified and analysed. With an accurate elevation data and images we could identify the detailed morphology in the inselbergs and examine the processes that actively alter the terrain. LiDAR data opened a view to the preglacial history and processes. Some preliminary estimations of the rate and amount of preglacial erosion could be made. It seems that erosion rate may have been in order of 2–10 m/Myr in Lapland based on existing datings and stratigraphic observations. Weathering and erosion history in Lapland is long as the kaolinite clays of Late Cenozoic, Mesozoic or even Mesoproterozoic in age are found in the weathered bedrock. Although all disconformities older than the Mesozoic era have probably been eroded to an unidentifiable extent, there is good reason to suppose that the main characteristics of the relief, including inselbergs, originated as early as the Late Cretaceous or at least in the Palaeocene.