At Flintaneset by Finnåsvika, in the centre of the municipality, we find the most beautiful and best preserved igneous rocks in western Norway. We must go to Hawaii or Island to find as fine structures as at Bømlo.
Holmengrå is the only place in Hordaland where we find traces of the abrasion that is supposed to have transformed Western Norway from a Himalaya-like high mountain landscape during the earth's Paleozoic Era, to a flat lowlands terrain during the Mezosoic Era. Just 400 million years ago, large and small stones plummeted down from the high mountains. Some of these stones became incorporated into the conglomerate bedrock on Holmengrå.
On Sandviksfjellet there are old boulders that have been made into mountains. The stones have been stretched out or squeezed together between huge slabs of rock, during slow, but powerfulprocesses of transport. This conglomerate shows, in quite a special way, the enormous powers that were active during the collision between Norway and Greenland over 400 million years ago.
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.
In the region of Ulven phyllite occurs with Hordaland's youngest fossils, and a beautiful quartz conglomerate. The phyllite and conglomerate got squeezed into the bottom of an ancient oceanic crust, made of gabbro and greenstone, in the heart of the Caledonide mountain chain.
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.