siida


Aksujärvi's summer home. Photographer Erkki Mikkola 1931. Museovirasto.
Ympäristö

 
 

 

The area of Lake Inari is a bit over 1000 square kilometers which makes it the third largest lake in Finland after Lake Saimaa and Lake Päijäne. Lake Inari is characterized by a vast archipelago made up of over 3000 islands and islets on the one hand, and on the other by large open tracts of water. The horizon line formed between water and sky is in many places unmarred by any trace of either island or land.

Geographically the bedrock of the bottom of the lake is composed of 2 to 3 billion year old schists. On the eastern side of Inari they are mostly bedrock gneiss and in the west slightly younger granites. A noteworthy factor in the surface formations of the Lake Inari area has been the folding of the earth‘s crust in eastern Europe that began about 70 million years ago. These led especially to the recent birth of the Alps, but this geological activity also affected the distant north through different kinds of plate movement. For example, the Köli mountain range arose in Norway then as did also Saariselkä and Hammastunturi areas as well as the fells of Lemmenjoki near Inari. On the other hand, Lake Inari and the nearby Sompio region sunk. Thus the depression in which the present Inari lowland is located was formed. The movement of the crust formed many great rivers like Ivalojoki that empties into Lake Inari.

The Ice Age and the Lake

The Ice Ages that began about a million years ago powerfully affected the formation of Lake Inari. The melting of the last ice occurred around Lake Inari about 9500 -10200 years ago. During the melting phase there was a large lake of ice at the location of the northern part of the present lake which poured its waters via the Näätämö waterway to the Arctic Ocean. Only when the ice dam at the location of Virtaniemi melted was the connection to the Arctic Ocean via Paatsjoki formed. It is nowadays the river the drains Lake Inari into the Arctic Ocean.

During the Ice Age, ice moved at Lake Inari in its glacial phase towards the northeast and retreated in its melting phase back towards the southwest. This movement is nowadays visible in various southwest-northeast directed formations in the landscape. The whole lake and especially the northeastern inlets are unidirectional with the flow of the ice sheet. As the ice advanced moraine ridges or drumlins and furrowed glaciated rock were formed. Melting waters dispersed gravel moraines which can be seen in the Lake Inari landscape such as in Partakko, Vatsari and Keväjärvi. The ice transported rocks and boulders as well. The amount of rocks that were left in the Vatsari area is amazingly abundant.

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A Lake of Great Natural Variety

A great diversity can be seen in the irregularity of the shoreline, its rockiness and the variable depth of the bottom as well as in the many islands and adjoining lakes. They are connected to Lake Inari either by rivers or larger channels. Examples of such lakes are Ukonjarvi, Nitsijarvi and the northeastern fjord-like lakes Kyyneljarvi and Suolisjarvi. The surrounding environment of Lake Inari is somewhat low but by no means flat. The average depth of the lake is just under 15 meters but the deepest spots are over 90 meters. There are no fells in the immediate vicinity but there are still several striking ridges. The nearest real fell is Otsamo, a few kilometers distant from the lake to the northwest.

The northern latitude of Inari is evident in the one and a half month long “Kaamos”, the dark season, which begins at the end of November or at the same times as the stretches of open lake normally freeze. An equally long summer day without night lasts a couple of months from May until the end of July. After a warm summer and autumn the large lakes may take a surprisingly long time to freeze. Lake Inari has a few narrow channels that never freeze.

Favorable Natural Conditions

The centre of Lake Inari is intersected by the 69th parallel. This makes Inari the northernmost large lake in Europe and it is situated further north than the northernmost part of Sweden and the whole Kola Peninsula. It is therefore quite special and noteworthy that Inari is located in the pine forest belt. These favorable natural circumstances are influenced by, among other things, the rather low altitude in relation to the sea level, the dominant southwest weather currents and proximity to the Arctic Ocean which is unfrozen even in winter.

The great open waters and the winds blowing off the northern part of Lake Inari have contributed to the development of a region of birch forests to the north. These birch woods fringe the shores in an irregular, thin band and cover some islands.

Treeless and tundra islands caused by the climate do not exist in Inari. The few barren islands are due to bedrock exposure, too much moisture or human activity. Pine trees shaped by wind and the scarcity of soil types such as are found for example, on seashores, are also found in Inari. There are spruces found in the utter southwest corner of the lake at the mouth of Ivalojoki. The lushest parts of Inari are all river mouths which formed broad lowlands and yearly brought abundant nutrients for the use of populations there.

Barrenness and Lake Regulation Characterize the Nature of the Lake

The water and shores of Lake Inari are otherwise low in nutrients. Along with this, the coldness of the water and the long duration of ice cover all contribute to the scarcity of water vegetation. This is seen in the small amounts of animals. The shore areas are narrow and rocky; sandy beaches are rare and they are narrow.

Another thing affecting the animal populations is regulation of the lake level. The Petsamo power stations drain the water reserves of Lake Inari to the point that in the spring the level of the water is usually at its lowest.  The level of the water begins to rise in the summer and it is at its highest before freezing. While the lake is unregulated the melting of snow and ice causes the greatest flooding in the spring which rapidly recedes in the beginning of the summer. This regulation of Lake Inari which departs from natural cycles has an effect on many organisms. Perhaps the clearest affect is on the waterfowl which try to nest in the spring on the shore near the waterline. During incubation the rising water interferes with the success of the nesting.

However, water birds nest on high shores, on lakes near Inari and by ponds on the large islands of Lake Inari which can be seen on the wild lake especially in the estuaries and shallow shores. Mergansers, red-throated divers (loons), divers and rarer common scoters are typical water birds of Lake Inari. This big lake also attracts straying and vagrant species from the Ocean. Sea eagles and cormorants are annual visitors and especially after storms certain bird cliff species like guillemots, puffins and kittiwakes have been encountered. Also the spawning of species of fish that have adapted to natural variations of water levels is disturbed by this regulation even though it is only at the most a couple of meters per year. The most important fish are many salmon-related varieties such as different species of whitefish, trout, arctic charr and occasionally also vendace. A considerable amount of fish fry are stocked in Inari to compensate for the harm caused by regulation.


Matti Mela



Photo: Martti Rikkonen
The unique character of Lake Inari is due not only to its large size but also its northern latitude and wildness, making it quite exceptional compared to other large, Finnish lakes.

 

 

 

 

 

 

Kove: Matti Mela
The ice normally breaks up at the transition between May and June, but the large open bodies of water do not melt until midsummer and, after hard winters, even later.

 

 

 

 

 

 

 

Kove: Martti Rikkonen
The large reservoir of water of the lake sheds warmth for a long time in the autumn and evens out differences of temperature between the days in the summer.

 

 

 

 

 

 

 

Photo: Martti Rikkonen

 

 

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