Siljan Ring Siljan Ring The Siljan Ring () is a prehistoric impact crater in Dalarna, central Sweden. It is one of the 15 largest known impact craters on Earth and the largest in Europe, with a diameter of about . The impact that created the Siljan Ring occurred when a meteorite collided with the Earth's surface during the Devonian period, about 376.8 ± 1.7 Ma. This coincides around the first Devonian extinction, the Kellwasser Event or Late Frasnian extinction at 376.1 Ma ± 1.6 Ma. The effects of the impact can clearly be seen in the bedrock in the area. The Cambrian,
Aero Country Airport period ending December 31, 2015, the airport had 9,000 aircraft operations, an average of 25 per day: 100% general aviation. At that time there were 244 aircraft based at this airport: 90% single-engine, 7% multi-engine, 0% jets, 2% helicopters, and 1% gliders. Aero Country Airport Aero Country Airport is a privately owned public airport in McKinney, Collin County, Texas, United States, located approximately west of the central business district. The airport has no IATA or ICAO designation. The airport is used solely for general aviation purposes. Aero Country previously used the FAA LID of TX05 until at least July 1997.