2010:34 The understanding of the formation of valleys and its implication on site characterization: Moredalen and Pukedalen, south-eastern Sweden

This report concerns a study which was initially conducted for the Swedish Nuclear Power Inspectorate (SKI), which is now merged into the Swedish Radiation Safety Authority (SSM). The conclusions and viewpoints presented in the report are those of the authors and do not necessarily coincide with those of the SSM.

In south-eastern Sweden, there are a number of over-deepened narrow valleys, more than 20 m deep, formed in Precambrian bedrock located above the highest post-glacial shoreline. Canyon-like valleys, called ”kursu” or kursu-valleys, are generally interpreted to be formed by glaciofluvial erosion.

An example of such a valley is Moredalen, which is a marked, approximately 7 km long, E-W striking valley that cuts through a plateau (c.140 m a.s.l.), an elevated block of the sub-Cambrian peneplain. There are also more open over-deepened valleys along which sub-glacial flow has occurred, e.g. Pukedalen which is a northwest-southeast trending valley incised in massive granite. Geomorphological features of this kind indicate certain characteristics of the bedrock that need to be considered in a performance assessment for a future nuclear waste repository.