Finland

Relief

Finland is heavily forested and contains some 56,000 lakes, numerous rivers, and extensive areas of marshland; viewed from the air, Finland looks like an intricate blue and green jigsaw puzzle. Except in the northwest, relief features do not vary greatly, and travelers on the ground or on the water can rarely see beyond the trees in their immediate vicinity. The landscape nevertheless possesses a striking—if sometimes bleak—beauty.

Finland’s underlying structure is a huge worn-down shield composed of ancient rock, mainly granite, dating from Precambrian time (from about 4 billion to 540 million years ago). The land is low-lying in the southern part of the country and higher in the centre and the northeast, while the few mountainous regions are in the extreme northwest, adjacent to Finland’s borders with Sweden and Norway. In this area there are several high peaks, including Mount Halti, which is, at 4,357 feet (1,328 metres), Finland’s highest mountain.

The coastline of Finland, some 2,760 miles (4,600 km) in length, is extremely indented and dotted with thousands of islands. The greatest number of these are to be found in the southwest, in the Turun (Turku; Åbo) archipelago, which merges with the Åland (Ahvenanmaa) Islands in the west. The southern islands in the Gulf of Finland are mainly of low elevation, while those lying along the southwest coastline may rise to heights of more than 400 feet (120 metres).

The relief of Finland was greatly affected by Ice Age glaciation.The retreating continental glacier left the bedrock littered with morainic deposits in formations of eskers, remarkable winding ridges of stratified gravel and sand, running northwest to southeast. One of the biggest formations is the Salpausselkä ridges, three parallel ridges running across southern Finland in an arc pattern. The weight of the glaciers, sometimes miles thick, depressed the Earth’s crust by many hundreds of feet. As a consequence, areas that have been released from the weight of the ice sheets have risen and continue to rise, and Finland is still emerging from the sea. Indeed, land rise of some 0.4 inch (10 mm) annually in the narrow part of the Gulf of Bothnia is gradually turning the old sea bottom into dry land.

Drainage and soils

Finland’s inland waters occupy almost one-tenth of the country’s total area; there are 10 lakes of more than 100 square miles (250 square km) in area and tens of thousands of smaller ones. The largest lake, Saimaa, in the southeast, covers about 1,700 square miles (4,400 square km). There are many other large lakes near it, including Päijänne and Pielinen, while Oulu is near Kajaani in central Finland, and Inari is in the extreme north. Away from coastal regions, many of Finland’s rivers flow into the lakes, which are generally shallow—only three lakes are deeper than about 300 feet (90 metres). Saimaa itself drains into the much larger Lake Ladoga in Russian territory via the Vuoksi (Vuoksa) River. Drainage from Finland’s eastern uplands is through the lake system of Russian Karelia to the White Sea.

In the extreme north the Paats River and its tributaries drain large areas into the Arctic. On Finland’s western coast a series of rivers flow into the Gulf of Bothnia. These include the Tornio, which forms part of Finland’s border with Sweden, and the Kemi, which, at 343 miles (550 km), is Finland’s longest river. In the southwest the Kokemäen, one of Finland’s largest rivers, flows out past the city of Pori (Björneborg). Other rivers flow southward into the Gulf of Finland.

Soils include those of the gravelly type found in the eskers, as well as extensive marine and lake postglacial deposits in the form of clays and silts, which provide the country’s most fertile soils. Almost one-third of Finland was once covered by bogs, fens, peatlands, and other swamplands, but many of these have been drained and are now forested. The northern third of Finland still has thick layers of peat, the humus soil of which continues to be reclaimed. In the Åland Islands the soils are mainly clay and sand.

Climate

The part of Finland north of the Arctic Circle suffers extremely severe and prolonged winters. Temperatures can fall as low as −22 °F (−30 °C). In these latitudes the snow never melts from the north-facing mountain slopes, but in the short summer (Lapland has about two months of the midnight sun), from May to July, temperatures can reach as high as 80 °F (27 °C). Farther south the temperature extremes are slightly less marked, as the Baltic Sea- and Gulf Stream-warmed airflow from the Atlantic keeps temperatures as much as 10 degrees higher than at similar latitudes in Siberia and Greenland. Winter is the longest season in Finland. North of the Arctic Circle the polar night lasts for more than 50 days; in southern Finland the shortest day lasts about six hours. Annual precipitation, about one-third of which falls as sleet or snow, is about 25 inches (600 mm) in the south and a little less in the north. All Finnish waters are subject to some surface freezing during the winter.