At the bottom of the Osa fjord there is a cultural landscape marked by great contrasts; the wide terraces and the river delta at the fjord contrast with the steep hillsides in the background, where Norddalen leads up to the mountain. There are two farms here. Osa and Sævartveit – the farm at the river mouth and the hollow by the sea.
Roughly 550 million years ago, what is now Finse lay at the bottom of the sea - the remains of mud and clay that were deposited in this sea have ended up on the roofs of Norway. Also the thrust sheet from the continental collision has found its way to Finse, after a several hundred kilometre-long, trek through the mountains, that took several tens of millions of years to complete.
There are coal bits hidden in the sand under Vatlestraumen. These remains from a geological layer from the Jurassic Period were discovered when the undersea Bjorøy Tunnel was built in 1994. Oil- and gas reservoirs in the Troll Field in the sea west of Hordaland are from the same time. It is, nonetheless, quite surprising to find bedrock from dinosaur time inside of the outer islands of western Norway. On the Scandinavian mainland north of Denmark, there are only a very few places where one f inds rock from this time in earth history.
There is no place in Hordaland where there are so many over-wintering song swans as in Tjeldstømarka. And there are few places in the county that have had this birdfowl as a guest for as long.