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.
Tronåsen (Duration: 1-3 hours)
About 1000 million years ago, all the land masses on Earth were joined together as a “supercontinent” called Rodinia. The area that became southern Norway was dominated by an ancient mountain chain. Mountain chains form when continents collide and become squashed together. Rocks near the surface are pushed up to form mountains while deeper rocks are pushed down to form the roots of the mountain chain. The rocks in the Tronåsen area are the roots of a long-gone mountain chain. The roots of the Himalayas look like this – but are still tens of kilometers below snow-covered mountain peaks and eight times hotter than boiling water. The rocks here are not only very old, they have also travelled a long way. When they were part of Rodinia, 1000 million years ago, southern Norway was located close to the equator.
Tronåsen was opened in 1844 and served as the main road from Stavanger to Kristiansand for 100 years until 1945. It was known to be the most difficult part of the road along the south coast with a gradient of 1:3 and 11 sharp turns. It was not unusual to push cars and buses up the hill. In 1931 Tronåsen was considered to be one of the most dangerous parts of the Monte Carlo Rally.
The road is closed during the winter months. During recent years more effort has been made to maintain the historical road, and it is open for summer traffic with smaller cars. The road is closed for large vehicles and for cars with caravans or trailers. You can access the Tronåsen historic road from the road E39, 4 km south of Moi.