Granite cliffs of Pyhäkoski

The ocean was closed due to a collision of tectonic plates. As a result, a mountain range was formed. Deep under the mountains some of the marine sediments crystallised to schists, or melted and re-crystallised into granites. The Lemmenpolku Nature Trail by River Oulujoki features reddish granite cliffs crystallised from molten rock. The bedrock in Isterinkoski Rapids by River Poikajoki represents deformed marine sediments.