Rocks and minerals

Igneous rock types have formed when molten volcanic rock or magma has cooled down over time. Igneous rock types can be divided into two subcategories depending on where they have formed. These subcategories are intrusive rocks and volcanic rocks.

Dense and sturdy intrusive rocks have formed deep within bedrock over long periods of time. The most common Finnish rock type, granite, is an example of an intrusive rock. It consists of three minerals: quartz, feldspar and mica. Granite can be easily distinguished from its red-grey colour.

Although intrusive rocks have formed deep within bedrock, the erosion of the ground layers above them has slowly brought them to the surface. This process has taken place over the course of millennia.

Due to their sturdiness, intrusive rock types such as granite are often used in buildings, roadsides, gravestones and memorial statues

The formation of volcanic rocks is connected to volcanic activity. When a volcano erupts, the magma contained within it is released to the surface of the Earth. When the magma arrives at the surface, it begins to cool down and solidify. Volcanic rock types are often porous, spongy, lightweight and matte-coloured. Although rocks of this type are rare in Finland, the bedrock of Iceland consists entirely of volcanic rock.

The most common type of lava rock is basalt. Pumice stones are lava rocks that are so spongy and light that they can float in water for a short time.

Sedimentary rock types are formed when rock material is set loose as the result of erosion and transported into the bottoms of bodies of water. Over the course of millennia, these materials are compressed into dense layers. In time, these layers form new types of rock.

Sedimentary rock types can be identified by the presence of distinctive layers and different materials. Sometimes, even the patterns caused by ancient waves can be seen in sedimentary rocks.

Sedimentary rock types include sandstone and claystone, the names of which suggest from what kinds of material the types of rocks have formed.

Limestone is formed when the lime-rich shells of dead clams and gastropods are layered and condensed into stone. Magnificent limestone banks can be seen on the shores of the islands of Gotland and Oland.

There are very few types of sedimentary rock in Finland. Sandstone can be found in the Satakunta region, claystone can be found near Oulu and limestone can be found in Parainen.

Metamorphic rock types have formed at same time as the ancient mountain ranges of planet Earth began to gain their shape. When mountain ranges formed near the borders of tectonic plates, the base rock became folded and surrounded by high temperature and pressure. The minerals contained in the bedrock began to arrange themselves in a different way, and the old types of igneous and sedimentary rock began to form new, metamorphic rock types.

The most common type of metamorphic rock found in Finland is gneiss. It has been formed from granite, which means that it contains the same minerals as the original igneous rock type. However, due to its changed structure, gneiss has more stripes than granite and is even sturdier.

The hardest rock type found in Finland is the metamorphic quartzite, which has been formed from sandstone. It can be found near the highest Finnish peaks, such as Koli.

Marble and mica schist are valuable types of metamorphic rock used in buildings. They have been formed from claystone and limestone, respectively.

Finland belongs to the same bedrock zone with the majority of Northern and Eastern Europe. Geologically speaking, it is among the oldest regions of Europe.

The majority of Finland's bedrock is estimated to have formed approximately 3 000 – 1 400 million years ago. This old, sturdy type of bedrock is found only in Fennoscandia. Elsewhere, it is covered by younger types of rock.

The region of the Baltic or Fennoscandian Shield covers an area from the Atlantic Ocean to the White Sea. Its north-eastern border can be seen on the slopes of the Saana fell in Northern Finland. Currently, the bedrock of Fennoscandia is relatively peaceful and flat. However, this was not always to case.

Some types of rock have formed when molten rock or magma has cooled down. Other types of rock, such as gneiss and mica schist, have been formed at the same time as the orogenic mountain ranges were created. When the age of such rock types can be determined, the age of different mountain ranges becomes clear.

Approximately 1 900 million years ago, Finland was located in a zone near the border of two tectonic plates. As the tectonic plates moved, they created two large mountain ranges: the Karelids and the Svecofennids. A long time ago, they were at least as tall as the Scandes are today.

The Karelids covered the area from Southwest Finland to Lapland, whereas the Svecofennids ran through Sweden and Southern Finland. Many Finnish hills and fells are the remnants of these ancient mountain ranges.

For millennia, the Finnish bedrock has been very stable. This is mainly due to the fact that the nation is located on top of a solid layer of rock that is approximately 230 kilometres thick. However, Finnish landscapes have been transformed significantly over the course of these millennia by water, snow and ice, as well as the glacial movements that have occurred during the various ice ages. These processes have worn down the Finnish bedrock and transported loose material towards the southern parts of the peninsula. It has been estimated that the last ice age alone wore down a layer approximately seven meters thick from our bedrock.

The movement of tectonic plates, the formation of mountain ranges and earthquakes can cause even the hardest bedrock to break and crack. The Kevonjoki canyon is located in the Kevo Nature reserve in Utsjoki. The canyon, which has formed as bedrock has torn apart, is the largest and most magnificent gorge valley in Finland. Finland is also home to a number of steep and often deep valleys, which have formed when blocks of rock have sunk in the ground. Some of these valleys have accumulated water over time, resulting in the formation of gorge lakes.

Some blocks of bedrock rise while other sink. This is how uplifted blocks of bedrock can form mountains and fault blocks. Although no uplifted mountain ranges can be found in Finland, there are many fault blocks, which were historically known as "giant's steps". Lake Inari and its surrounding environment has been moulded by these kinds of processes.

The Scandinavian Mountains or the Scandes are an orogenic mountain range that formed approximately 400 million years ago as the result of colliding tectonic plates.

The original Scandes were among the oldest orogenic mountain ranges in the world. They are estimated to have been almost tens of kilometres tall during their youth. Over the course of millennia, the mountain range was weathered down and flattened almost completely by erosion, before rising up once again as a young orogenic mountain range during the same time as the Central European Alps were formed.

Nowadays, the highest peaks of the Scandes are located in the Norwegian Jotunheimen region. Today, the highest peaks are only approximately 2.5 kilometres tall (Galdhöpiggen 2469 m, Glittertind 2464 m). The northernmost parts of the mountain range have been eroded into fells, which is the case with the Swedish Kebnekaise (2117 m) and the Finnish Halti (1324 m).

The Scandes are the highest mountain range in Northern Europe. The mountain range also acts as a watershed that divides the catchment areas of the Atlantic Ocean, the Arctic Ocean and the Baltic Sea. The Finnish and Bothnian Gulfs of the Baltic Sea receive water from various long and slow rivers, such as Kemijoki. Of the large Nordic rivers, only the Norwegian Glomma, the Swedish Göta and the Finnish Teno flow elsewhere.

There are no region in Europe that is as rich in lakes as Fennoscandia. The largest Fennoscandian lake is the Russian Ladoga. The largest Finnish lake is Saimaa, which is part of the Vuoksi water region. The waters of Lake Saimaa flow to Lake Ladoga via the river Vuoksi. From Ladoga, the water flows into the Baltic Sea through the river Neva.