On the island of Härnön, situated 6–8 km SE by S of the town of Härnösand, boulders of Lower Ordovician red Limbata limestone have been found. The boulders all occur on the south-eastern shore of the island in shingle the parent material of which is till. The limestones are probably derived from beds resting upon the bottom of the Gulf of Bothnia E or NE of the island. They indicate the northernmost extension, so far known, of the area of Palaeozoic rocks on the bottom of the Gulf, the so-called South Bothnian District.