There is evidence that the drainage divide between the Norwegian Sea and the south-east flowing rivers were once further west. Glacial erosion is thought to have contributed to the shift of the divide, which in some cases ought to have been in excess of 50 km. Much of the Scandinavian Mountains has been sculpted by glacal erosion. The mountain chain is dotted with glacial cirques usually separated from each other by pre-glacial paleosurfaces. Glacier erosion has been limited in these paleosurfaces which form usually plateaus between valleys. As such the paleosurfaces were subject of diverging and slow ice flow during the glaciations. In contrast valleys concentrated ice flow forming fast glaciers or ice streams. At some locations coalesced cirques form arêtes and pyramidal peaks. Glacial reshaping of valleys is more marked in the western part of the mountain chain where drowned glacier-shaped valleys constitute the fjords of Norway. In the eastern part of the mountain chain, glacial reshaping of valleys is weaker. Many mountain tops contain blockfields which escaped glacial erosion either by having been nunataks in the glacial periods or by being protected from erosion under cold-based glacier ice. Karst systems, with their characteristic caves and sinkholes, occur at various places in the Scandinavian Mountains, but are more common in the northern parts. Present-day karst systems might have long histories dating back to the Pleistocene or even earlier.