Introduction to the periglacial environment in Finland

Abstract

An overview is presented of the periglacial characteristics of climate and landforms in Finland. Mean annual air temperature (MAAT) in Finland ranges from +5.5 to -3°C, and frost sums in most parts of the country are large enough for active seasonal frost. Local conditions are more important in the formation of frost features than the overly general mean values of air temperature, however. Snow depth is the critical factor for most frost features, and permafrost is observed only in northern parts of the country, where thin snow cover supports frost activity. A brief description of features indicating frost activity is presented. Palsas, pounus, and string mires are peat landforms designed by frost. Fell slopes exhibit additional features of talus, slush flows and gelifluction lobes and terraces. Frost heave and contraction cracking are characteristic features occuring even in fields in southern Finland. Active frost-sorted patterned grounds are common in northern Finland, especially at the bottoms of shallow, seasonally dry ponds. Ground water close to the surface is essential for the formation of most frost features. Special forms of both aeolian and fluvial activity are part of the periglacial environment in Finland. Snow drift and deflation of sand surfaces formed by glaciofluvial processes during deglaciation are part of the periglacial environment in Lapland. Drastic spring floods with ice dams formed in river channels are typical for northern rivers. Proposals for further studies are made at the end of the paper.

Keywords

• eatures
• palsas
• frost heaving
• patterned ground
• eolian features
• Holocene
• Lapland
• Finland