Bays that are shallow far out into the sea, with fine sand and clay, are rare in Hordaland. Where they are found, the reason is usually that the edge of the glacier made smaller advances or stopovers when it calved back at the end of the last Ice Age. This is what happened at Vinnesleira.
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.
When the lush beach area innermost in Ulvikapollen was protected, the bird life was instrumental to the decision. The plant diversity is just as impressive. In Hordaland sea meadows such as this are rare small in size - they are more common in coastal environments.
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.
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.