The bedrock is made up of Småland granite. In the loose deposits, moraine with an abundance of boulders prevails.
The upper layers in particular often have large boulders. Along the eastern boundary of the area, a small amount of ice river material is present. Today rock is exposed only on Idhöjden and in the north-western section. The entire area lies above the highest coastline, which in this part of Sweden is about 135 metres above sea level. The moraine, therefore, has not been surged by the action of the sea.