The gneisses of the Lake Oulujärvi belong to the oldest bedrock area of the EU. They have crystallised deep under an ancient mountain range. The mountains formed in a collision of Earth´s early continents. At that time the Earth´s atmosphere was lacking oxygen, and primitive cyanobacteria living in oceans were the most developed form of life. You can explore gneisses for example in Kilonniemi on Manamansalo island.