Kieksi conglomerate outcrop

In the Muhos region, a block of bedrock started to sink and became a shallow bay. At first, gravel, sand and silt were deposited in the deltas of ancient rivers discharging into the depression. As the sea deepened, clay was also deposited on its bottom. The deposits crystallised to sediment rocks of Muhos formation. You can see an outcrop of gravel stone in a cliff by River Oulujoki, close to Montta. Sediment rocks of Muhos formation contain fossils of primitive unicellular organisms.