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About This GigapanToggle
- Taken by
- Jouko Vanne
- Explore score
- 1.34 Gigapixels
- Date added
- Oct 25, 2011
- Date taken
- Oct 25, 2011
Rokua Geopark – the world’s northernmost
Listed in UNESCO’s Global Geopark Network, which comprises 77 geological heritage sites of particular importance, rarity or aesthetic appeal all over the world. Rokua is Finland’s only and the world’s northernmost member of the network, which it joined in October 2010.
The geopark covers an area of 1,300 sq. kilometres stretching from Muhos along the River Oulujoki to Lake Oulujärvi. It is bounded on the north by the river and on the south by the magnificent Rokua glacial ridges.
Heritage of the Ice Age
Rokua Geopark tells the story of the genesis of Rokua, Lake Oulujärvi and the Oulujoki River Valley, the heritage that the Ice Age left. The history of the people who moved here as the ice sheet melted and the shoreline receded is combined with the story of that heritage. The geopark offers an excellent opportunity to see a unique natural setting and enjoy genuine products, experiences and tales. It promotes sustainable development, tourism and teaching of the natural sciences. The landforms, flora and fauna as well as the culture there owe their genesis to the history of the area and especially the geological events that have been profoundly shaping the land in the course of the ages.
Geology and nature
Rokuanvaara Hill was formed from strata of sand deposited by a river flowing through a tunnel underneath a glacier and into a glacial bay that formed as the ice gradually retreated 10,800 –10,500 years ago. The exceptional character of the soil is reflected in the vegetation, the characteristic feature of which are heaths carpeted by vast swathes of off-white Iceland moss lichen.
Rokua National Park offers the hiker so much to see and do. The park contains waymarked hiking trails that wind their way through ancient forests and past kettle holes filled with crystal-clear water. There are places where you can make a campfire and you have the option of staying overnight in the Pitkäjärvi campsite.
Syvyydenkaivo, the name of which means “Well of Depth”, is Finland’s deepest kettle hole. It came into being when a huge block of ice buried in the layers of sand in the estuary of a the river flowing underneath the glacier melted, creating a deep depression. The true depth of most of the kettle holes in Rokua is concealed by a pond of clear water or a bog in their deepest part.
Utajärvi Stone Park is a place where you can travel through time to witness the development of Finland’s bedrock. The first stone along the Time Trail in the park is Siurua gneiss, some 3.5 billion years old. It is also the oldest known rock in the European Union.
Isterinkoski is the name of a set of foaming rapids in the River Poikajoki as it descends from meta-greywackes two billion years old into a depression filled with claystone that is almost as ancient. All in all, the rapids fall about 30 metres.
The Lake Oulujärvi district was freed from the ice sheet some 10,500 years ago. The modern lake came into being when the land rose and cut off a bay of the vast Ancylus Lake about 9,500 years ago. Sometimes nicknamed the “Kainuu Sea” after the region in which it lies, the lake is now about twice as long as it was when it first came into being. This is due to the unevenness of the uplift, which has tilted the basin in which the lake lies towards the south-east.
Manamansalo is the name of an island in Lake Oulujärvi. It's 80-kilometre shoreline consists mainly of sandy beaches. The central part of the island is a spreading expanse of esker (glacial) ridges that were deposited on top of bedrock over 2.5 billion years old. The hiking trails there wind over gneiss rock and present also other magnificent forms of bedrock associated with the melting glacial ice (Rokua Geopark).
See also: www.maanmittauslaitos.fi/en/node/3177