Natural Features of Kolvananuuro Nature Reserve

Birth of the Kolvananuuro Gorge  
Kolvananuuro Vegetation and Animal Species

A Beautiful Gorge

Kolvananuuro is a long, steep-sided and fascinatingly beautiful gorge. The gorge's unique vegetation types attract many nature loving visitors. Kolvananuuro, which means Kolvana Gorge is part of a steep-sided fracture valley which is tens of kilometres long. Kolvananuuro Nature Reserve is about 4 km long and 400 m wide. Outside of the nature reserve the gorge continues to the south covered by a dry forest on a sand bed and after this as several river valleys. The fracture valley which runs from northwest to southeast was formed millions of years ago as the rock bed shifted.

The gorge is surrounded by rugged cliffs. The cliff walls rise to 70 - 80 m from the gorge floor. On the west side of the nature reserve Verkkovaara Hill rises up to 100 m. There are practically sheer cliff walls south of Lake Pieni Koiralampi and at Pahakallio Rock at the north end of the gorge. The cliff wall at Pahakallio is bare of vegetation, but other steep cliff walls are covered by old spruce forest. There are also spruce growing at the top of cliffs. The area's old-growth forest, which is untouched by forestry, is one of the nature reserve's greatest sources of pride. The slopes within the nature reserve are also in their natural state. They are alternately covered by lush herb-rich forests, shrubs or coniferous forests or are barren and rocky or sheer cliffs.

The bottom of the gorge is covered by narrow boggy spots, barren small lakes, brooks and rocks. The source of the brook, which winds through the rocky terrain, is in the middle of mires at Lake Pieni Koiralampi. There are magnificent fern forests along the banks of the brook. Northern and southern species meet up in Kolvananuuro Gorge.

The gorge begins behind Lake Koiralampi. Photo: Tarja Martin

Birth of the Kolvananuuro Gorge

Kolvananuuro kanjon. Photo: Matti PihlatieApproximately 2 billion (milliard) years ago the area was moulded by the formation of a chain of mountains. The tension in the rock bed became so strong that it caused plates to shift and mountains to fold. This is how the Karelid Mountains, which were much like the present Alps, formed between Lake Pielinen and where the town of Kuopio is now. They reached south to north from Lake Ladoga to Lapland. About 1.8 billion (milliard) years ago when the folding was coming to an end Kolvananuuro fault formed as the rock bed cracked and shifted in chunks. The fault is still visible from the top edge of the canyon.

During a period of hundreds of millions of years ice ages and erosion have levelled the mountains to fells. Today only the roots of the ancient kilometre high mountain chain are left. In the Kyykkä area, which is next to Kolvananuuro, the very roots are visible or are under a very thin layer of earth. A sample dating 2,3 billion (milliard) years has been taken from Kyykkä and studied. The research helped scientists understand how the oxygen levels in the Earth's atmosphere evolved to their present level.

The gorges which are now at Kolvananuuro and Kalliojärvi were formed during the last Ice Age, when flowing ice carved them deep into the rock bed. When the ice melted the waters washed away sand from the gorge walls and exposed them. The sand flowed into the Yoldia Sea and formed a sand delta there over 9000 years ago. Kolvananuuro is the only place in Finland, where it can be definitely stated that the rock layers were formed during the Ice Age. The different phases of the rock beds history can be seen clearly on the gorge's western wall by the many different layers there.

At present the gorge walls are eroding little by little. As a result boulders of stone roll to the bottom of the gorge.

Rock Types at Kolvananuuro Gorge

The rock types in Kolvananuuro tell a lot about the area's geological development. The most typical rock types in the gorge are metaconglomerate, mica schist, quartz sericite schist and metadiabase. Metaconglomerate, which has a dotted pattern, and mica schist, which glitters, were formed by glaciers during the Ice Age 2.5 billion (milliard) years ago and are the area's oldest rock types.

Gray quartz sericite schist was formed as the earth's crust eroded because the Earth's climate warmed dramatically. All the area's minerals, other than quartz, eroded into clay were washed away. The area had great changes in altitude and flowing water transported loose material (quartz) from slopes to flat ground, where it has become layered (quartz schist).

The metadiabase grooves were formed 2,2 - 2,1 billion (milliard) years ago. They are a result of volcanic activity: melted rock forced its way to the Earth's surface. The dark grooves are visible between light coloured quartzite dikes. 

Kolvananuuro Vegetation and Animal Species 

The Fascinating Diversity of Northern and Southern Species

The unique vegetation of the gorge is a result of the soil's and microclimate's diversity and of how vegetation spread during the end of the Ice Age, which ended 11 400 years ago. Kolvananuuro Gorge was an ancient route along which vegetation species spread between Lake Ladoga and Kuusamo region, when the land of what today is southern Finland was still buried under ice. The temperature and humidity of the gorge's slopes changes constantly and for this reason species from both the north and south can survive side by side. The gorge is very deep and growth conditions differ considerably at different altitudes. Part of the reason for this is the amount of direct sunlight or how much shade certain parts get. Summer arrives late in the shady areas of the gorge.

Given time these ferns will grow into a jungle. Photo: Markus Sirkka

The Orpine (Sedum telephium) and the Angular Solomon's Seal (Polygonatum odoratum) are demanding southern species which grow at the bottom of cliff walls. Other demanding southern species are the Hedge Woundwort (Stachys sylvatica) and the Sweet Woodruff (Galium odoratum), which grow in herb-rich forests on hillsides. As well as the shrub-like Small-leaved Lime (Tilia cordata) the Fly Honeysuckle (Lonicera xylosteum) and Mezereon (Daphne mezereum) are also very common in the area. Northern species can be found on the cool cliff walls. Some northern species growing there are the Green Spleenwort (Asplenium viride), the Alpine Saxifrage (Saxifraga nivalis), the Alpine Mouse-ear (Cerastium alpinum), the Alpine Woodsia (Woodsia alpina). The Diplazium sibiricum, which is rare in Finland, grows lushly in fern groves by the brook. At the bottom of the gorge and on its western slope there are several lush fern groves in a narrow region. The Ostrich Fern (Matteuccia struthiopteris), which can grow to be the height of an adult person, forms fern jungles on the brook bank. The feather-shaped Ostrich Fern is at its grandest during June.

Life Around the Lakes and Brook

There are two small wilderness lakes in the nature reserve; Lakes Suuri Koiralampi and Pieni Koiralampi. The smaller of the lakes, Pieni Koiralampi, is slowly overgrowing. The shoots of Bogbeans (Menyanthes trifoliata) and Marsh Cinquefoils (Comarum palustre) reach from the shores across open water. The shoots support a layer of spaghnum moss, which is the surface bog vegetation grows on. Paludification improves conditions for butterflies and moths and their populations grow. The Swallowtail (Papilio machaon) for example lays its eggs on Milk-parsley (Peucedanum palustre) or Wild Angelica (Angelica sylvestris). There is a narrow sedge area between the two lakes.

Lake Pieni Koiralampi narrows at its southern end and becomes a brook, which at times disappears from sight. On sunny summer days much activity can be seen on the surface of the brook. The minnow (Phoxinus phoxinus), which is the length of a human finger, swims in small groups searching for insects, small shellfish and worms to eat. A canal which was dug at the beginning of the 20th Century, flows to Lake Iso Koiralampi from Lake Matolampi, situated west of Kolvananuuro Gorge. At the mouth of this canal there is a dam built by a beaver which has inhabited the area for decades.

Songsters in the Groves

Many different bird species thrive in the gorge much better than they do in the forests surrounding it. The walls and slopes of the gorge offer many sheltered nesting spots and varied vegetation. There is a large Wren (Troglodytes troglodytes) population in the shady forests on the slopes. The Wren and the Wood Warbler (Phylloscopus sibilatrix) are the loudest songsters in the gorge. Other birds often heard there are the Chaffinch (Fringilla coelebs), various warblers, the European Robin (Erithacus rubecula), the Goldcrest (Regulus regulus) and the Eurasian Siskin (Carduelis spinus). Some rare species, such as the Arctic Warbler (Phylloscopus borealis) and the Red-breasted Flycatcher (Ficedula parva), which are old-growth forest species, can also be spotted in the area. The most common birds of prey are the Northern Goshawk (Accipiter gentilis), the Eurasian Sparrow Hawk (Accipiter nisus), the Eurasian Buzzard (Buteo buteo) and the European Honey Buzzard (Pernis apivorus).

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