The Kalajoki dune field on the west coast of Finland

Abstract

The Kalajoki dune field, located on the coast of the Gulf of Bothnia in the area of most rapid land uplift in Finland, is one of the largest active blown sand areas in the country. The morphology of the area and the material composition, inter­nal structure and genetic relations of its deposits are studied here from maps, air photographs, field observations and grain size analyses. Radiocarbon dating and dendrochronology are used to trace the history of' the area and determine the nature of' the aeolian processes.

The dune field, about 300–400 m wide and 2.5 km long, is located in con­junction with an esker which terminates at the coast. A well-developed podzol soil horizon containing some charcoal is found beneath the main transversal shore dune in many places. This suggests that most of the present dune area gained a permanent vegetation cover soon after its emergence from the sea and retained this for at least 500 years. Destruction of the forests in the area began only when a dune which had accumulated beyond the littoral zone started to migrate inland once again at the beginning of the 19th century, evidently prompted by a forest fire. It has now advanced some 200 m, at an average speed over the last hundred years of almost 1 m/yr. Aeolian activity in the area has decreased markedly in recent times, however, especially since the cessation of sheep grazing in the 1940's, and the shifting of the main dune has practically come to a standstill.