The Siljan Ring (Swedish: Siljansringen) is a prehistoric impact crater in Dalarna, central Sweden. It is one of the 18 largest known impact craters on Earth and the largest in Europe, with a diameter of about 52 km (32 mi). The impact that created the Siljan Ring occurred when a meteorite collided with the Earth's surface during the Devonian period, about 377 million years ago.[2] The effects of the impact can clearly be seen in the bedrock in the area. The Cambrian, Ordovician and Silurian sedimentary rocks deformed by the impact are rich in fossils.