used as sightlines in this suggested manner. Certain late 1st-millennium picture stones on Gotland carry grooves that have been made after the relief of the stones was carved, which show the grooves to be late. Likewise with the level above current sea surface of the lowest grooved outcrops on the island, that shows them to be no older than AD 1000 judging from post-glacial shoreline displacement. It has been suggested that on one picture stone, part of the Late Iron Age decoration is carved into the bottom of a groove, meaning that this groove must be older than the picture. References External links Archaeology of Sweden Archaeoastronomy Neolithic