Ritlandskrateret is an impact crater formed by a meteorite impact at a time sometime ca. 500 million years ago. It is about two and a half kilometres across and is believed to be the work of a meteorite about 100 metres in size.
The whole area was a geological mystery until quite recently, as the site is marked not only by a meteorite impact, but also by the meeting of lithospheric plates that formed the Norwegian mountain ranges, and the area was part of its history as a seabed. A complete geological nut for scientists.