Rare forms of meltwater erosion on bedrock: polished flutes in the Åland Sea area, Sweden-Finland

Narrow, polished flutes have been formed on bedrock surfaces at a number of localities on the south-western and north-eastern sides of the Åland Sea. These were eroded by subglacial, sediment-charged meltwater. The fluted surfaces are polished, in sharp contrast to the surrounding, coarser bedrock surfaces with glacial striae. The glacial striae have been rubbed off from the fluted surfaces at most sites and replaced by comparatively deep and narrow erosion marks.