Gneiss rocks are examples of the oldest continental areas in Rokua Geopark. The oldest gneiss rocks in the Lake Oulujärvi area came into being about 2,700 – 2,600 million years ago. At that time there was no oxygen in the planet’s atmosphere and life had developed to the level of primitive cyanobacteria. The long history of the gneiss rock is shown by the stripes and powerful creases in its appearance, which come from the movements of the Earth’s crust, e.g. when tectonic plates collide.
Gneiss dating back millions of years
You can see gneiss rock in several locations in Rokua Geopark. The oldest rock in Utajärvi kivipuisto, Siurua gneiss, is 3.5 billion years old and the oldest known rock in the EU. Gneiss can also be seen at Pirunkallio (the Devil’s Rock) in Säräisniemi, the source of the footings for Säräisniemi church, for example. There is also gneiss in Kilonniemi in Manamansalo and in Kivimäki and the beach at Kultahiekat in Rytölahti. The exposed gneiss rock at Kilonniemi in Manamansalo has signs with information about the fascinating forms the rock takes.