Evolution of eolian relief of the Kaamasjoki–Kiellajoki river basin in Finnish Lapland

Abstract

The aim of this study is to explain the dunes and deflation relief formed from sediments accumulated in an ice‑dammed lake during the deglaciation in the Kaamasjoki‑Kiellajoki river basin (69°15’‑69°25'N, 26°30'‑27°05'E). At present the dunes are parabolic fossil dunes formed in periglacial conditions having been deposited by winds blowing from directions lying between WNW and NW. In the subarctic conditions prevailing today eolian activity resulting from the fact that effective wind directions are between W and SW is principally one of deflation.

The rise in the level of the ground water during the Atlantic period caused deflation lakes to be formed in the spaces between the dunes. Two bathymetric maps of these lakes were made.

In granulometric composition and sorting the eolian material is normal blown sand. x(Md) = 0.20 mm. Ø, x(S₀) = 1.32, x(Sk) = 0.99, and x(K) = 0.27. The sand contains considerable quantities of heavy minerals (x = 34.6 % by weight) of which the most important are hornblende, garnet, pyroxenes and magnetite. The quartz grains are very slightly rounded. The degree of roundness was measured using a Krygowski mechanical graniformameter.

Five radiocarbon datings were carried out on specimens taken from the area: 2 from a palsa bog, 1 from a peat bog formed in a deflation lake, 1 from a bog situated between dunes and 1 from a layer of coal buried in sand between podsol horizons. Three of the datings were combined with pollen, spore, seed and diatom analyses of samples taken from the bogs.

The results of the investigation into the evolution stages of eolian relief are presented in a chronological table in which are also given the periods of vegetation history, the types of vegetation, the climatic conditions and the estimated average July temperatures.

Presented as an appendix is a detailed geomorphological map of the area.