Dverghamrar (Dwarf Rocks), a protected natural monument just east of Foss, are peculiar and beautiful formations of columnar basalt. On top of the columns there is cube-jointed basalt. The landscape is thought to have been moulded at the end of the Ice Age, as the sea level was higher at that time and it is believed that the waves caused the peculiar look of the rocks. Columnar basalt is formed when lava flow gets cooled and contraction forces build up. Cracks then form horizontally and the extensive fracture network that develops results in the six sided formation of the columns.