The parabolic blowout dune of Kangasjärvi in Saarijärvi, central Finland

Abstract

This study describes the morphology, internal structure, sediment and origin of a parabolic blowout dune located at Kangasjärvi in Central Finland. The U-shaped dune is an isolated feature situated on a sand plain close to an esker ridge. It is from 350 to 650 m long, from 30 to 40 m wide and from 2 to 4 m high. The sand in the dune originates from a large deflation basin situated west from the dune. The dune sediment is composed of well sorted fine grained sand. The grain size, the mineral composition and the roundness of the mineral grains of the dune sand do not differ from those of the source sediment. The formation of the dune began when the underlying sand plain rose above the level of Ancylus Lake at the end of the Preboreal chron around 9400...9350 years BP. The location of the deflation basin to the west of the dune, the parabolic form of the dune, the asymmetry of the dune head and the internal structure of the dune suggest that the dune was formed under periglacial climate by winds blowing from the west and northwest. Because the dune has retained its parabolic shape, it was probably gradually vegetated during its formation. It is believed that dune formation lasted for only a short time. The dune is now densely vegetated.

Keywords

• eolian features
• dunes
• geomorphology
• sand
• genesis
• Holocene
• Saarijärvi
• Finland