Permafrost and patterned grounds in Finland - periglacial or something else

Abstract

Northernmost Finnish Lapland is periglacial. This area belongs to the zone of sporadic and alpine permafrost. Microclimatic permafrost can be found in eskers, caves and artifacts like mines everywhere in Finland. Periglacial permafrost occured in Southern Lapland and Ostrobothnia during some early Weichselian interstadial and at Salpausselkä zone and in the supra-aquatic parts of North Karelia during Yonger Dryas. Nowadays the Southern and Central Finland are no more periglacial. Patterned grounds occur in all parts of Finland. Their number and species vary in different parts of Finland. In Northern Lapland the variety of patterned grounds is most polymorphous and sorted and nonsorted patterns are equally common. In Southern and Central Finland the big, sorted types like boulder depressions and sorted nets account for over 90 % of patterned grounds. The processes forming patterned grounds are very active in Northernmost Lapland, but less active or fully fossilised in Southern Finland. The significance of local circumstances increases on the forming of patterned grounds in the south.

Keywords

• periglacial features
• permafrost
• patterned ground
• ice wedges
• boulder depressions
• genesis
• Quaternary
• Finland