Tuesday, April 28, 2015
The grooves on the island of Gotland in the Baltic Sea: a neolithic lunar calendar
Astronomical Observatory, Uppsala University, Sweden
On the island of Gotland, in the middle of the Baltic Sea, there exist about 3,600 groove cut in the bedrock or on big stones. They can be found on the ancient shores of lakes and in connection and in connection with the coastal settlements and finds of the Neolithic Pitted Ware Culture. The grooves have a typical length of 50-110cm, width of 5-10cm, and depth of 1-10cm. They follow closely a circular arc in both the length and width cross-sections (Fig. 1; 2). The surface is very smooth and they must have been cut by a stable machine using quartz sand and water (Fig. 3).