Natural stone circle
Natural stone circles (also known as rock gardens) cover the ground in parts of Alaska , in the high Alps and on the Norwegian islands of Spitsbergen . Elsewhere, stones form islands, mazes, polygons, and stripes on the ground.
Some of the circles or polygons have a diameter of more than one meter. The soil within the “stone walls” consists almost exclusively of sand or fine rubble. The patterns often cover several hundred square meters, with the boundaries of the surfaces rarely being sharply defined. The regular forms often end without a clearly recognizable cause in the landscape.
According to scientists who have studied the phenomenon, cyclical freezing and thawing of the soil leads to simple feedback mechanisms that create these remarkable patterns.