Drumlins in the Gulf of Bothnia

Abstract

Drumlins are relatively small, elongate hills aligned with ice-flow direction (Menzies 1979). The name drumlin originates from the Irish word druim, which means rounded hill. They are among the most widespread glacial landforms. Drumlins are often likened to half-buried eggs or inverted spoons, with one slope blunter than the other. They belong to the group of ice-flow-parallel glacial landforms that includes glacial striae, flutes, crag-and-tails and mega-scale glacial lineations. Drumlins are very common in the landscape of central and northern Scandinavia (Hattestrand 1998), but their identification in the Baltic Sea and Gulf of Bothnia has been hindered by a lack of seafloor data. Here we show a drumlin field from the southern Gulf of Bothnia. The drumlin field shown in Figure 1 stretches for >85 km and probably continues northwards beyond the coverage of the high-resolution bathymetric data available for this study. The outlines of the drumlins are generally easy to distinguish (Fig. 1c), although their surfaces are frequently scarred by iceberg ploughmarks and pits (Fig. 1e, f). The drumlins are aligned NNW–SSE (169°) and their morphology changes progressively along the mapped section. The northern part is characterized by shorter, wider drumlins, whereas …