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.
Deep down between the stone polished phyllite bedrock in Bordalsgjelet canyon, there is a cascading river. In close cooperation with hard polishing stones, the water has carved into the bedrock for thousands of years - and is still doing so today.