Fljótsdalur, the valley district between the rivers Hrafnsgerðisá on the west and Gilsá on the east. The lower part of valley near the Lagarfljót river is broad with meadows, and about 10 km from Lagarfljót it divides into the narrow valleys Norðurdalur and Suðurdalur, between which is the mountain spur Múli (642 m).