Aerial LiDAR analysis in geomorphological mapping and geochronological determination of surficial deposits in the Sodankylä region, northern Finland

Abstract

Geomorphological mapping based on an aerial light detection and ranging (LiDAR)-derived digital elevation model, field observations, ground penetrating radar measurements and test pit surveys was carried out in a glaciogenic environment in Sodankylä, central Finnish Lapland. The mapping area covered about 370 km2, with the LiDAR data having a pixel size of 2 m × 2 m and vertical resolution 0.3 m. The geomorphology of the area consists of large till-covered hills, ground moraine plains, glaciofluvial sand and gravel deposits composed of esker systems and related delta and outwash formations of the Weichselian cold stages, followed by pro-glacial glaciolacustric and post-glacial lacustric and fluvial sand/silt deposits. Furthermore, large areas in topographical depressions are covered by Holocene mires. The benefits of LiDAR data compared to traditional aerial-photo-based interpretation were in more detailed identification of surface deposits and more precise edging of the morphologies. This reflected more accurately the true ground surface in areas of dense vegetation. As an example, based on the LiDAR mapping it was possible to distinguish several till-covered delta and sandur deposits which based on OSL dating date back to the Early Weichselian stadial (74–89 ka). The results of the mapping project have been collated and published in a Quaternary geological map of the Sodankylä region.