Mapping of Quaternary Geomorphology in Southern Dalarna: a LiDAR Study

Abstract

The Quaternary has been a period that has seen a fluctuation in glaciation, in Sweden, for 2.5 million years, with the last glaciation vanishing around 9.6 cal kyr BP. Left behind are glacial landforms that can help us understand the behavior of the ice and the processes which shape our landscape. Earlier works has set out to map these landforms and to determine the history of the ice. Since the advent of LiDAR, mapping these features has become easier and more precise, and they can be used to make detailed maps. Since it is a relatively new tool, the extent of mapped features is limited. The purpose of this study is to map glacial landforms in southern Dalarna, central Sweden, where no LiDAR mapping has been done before, and to further connect what is found to earlier works. What glacial landforms are prominent in the area and what are their extent? To find out, mapping was undertaken in QGIS using LiDAR data; where shapefiles (lines and polygons) came to represent the mapped landforms. Lineations, meltwater channels, eskers and murtoos fields became the four feature categories which were mapped. The extent of the mapped features, is used to draw conclusions regarding their quantity and extent and to further connect them to earlier works, such as an ice-margin map over the deglaciation of Fennoscandia. Meltwater channels are abundant but their spread was limited to a few areas. Eskers have a high spread but were few in number, while sometimes being very large in regards to their length. Murtoos fields are few in number but are prone to cover large areas in the few places where they appear. The most mapped feature is glacial lineations, which were spread out in almost every part of the study area and were high in quantity. Using the general orientation of the lineations, a comparison could be drawn between the lineations and the ice-margin map over the deglaciation of Fennoscandia. The comparison showed that the ice-margin map agreed with the mapped lineations. The landforms found also tells of a rapid deglaciation and the ice being warm bottomed.