Some of the oldest rocks in Magma Geopark and in southern Norway are found near Tronåsen. Some of the gneisses in this area were originally formed more than 1.600 million years ago on an ancient sea floor. The historical road over Tronåsen is part of the first road for wheeled vehicles between Stavanger via Kristiansand to Oslo. This road is one of Norway’s best-known roads since it was used during the Monte Carlo Rally in the 1930´s.