Pattern of dead-ice deglaciation forms in western Kemijärvi, Northern Finland

Abstract

A few kilometres to the west of the Kemijärvi church there is a ridge‑and­-mound field. The ridges and mounds are grouped in chains, which cross each other at right angles to form a network‑like pattern. The chains can be divided into formations parallel to the last glacial flow (radial, longitudinal) and formations parallel to the ice edge (transversal). Both radial and transversal formations consist of material like kalix till. To judge from the material, structure and morphology, all these forms can be explained as supraglacial or glacial karst dead‑ice accumulations. They developed under deglaciation conditions similar to those now prevailing at the ice edge in Spitsbergen. Melting of the inactive ice edge buried under a thick mantle of melt‑out material took place in shallow water. The general orientation of the visible ice front during the deglaciation phase was from the south‑west to the north‑east, although in fact big inactive ice bodies existed under the mantle of various supraglacial ac­cumulations long after this phase. The dead‑ice features so characteristic for the deglaciation forms of the study area were caused by the slow melting in the final deglaciption phase.