Geology

Finland became a country with an extraordinary amount of water in it because of geological conditions that pre-date the creation of the country by many thousands of years. Although there are no glaciers in Finland now (despite a large amount of the country being located in the Arctic Circle) the effects of glacial erosion can be seen in the geography and lake formation in Finland in the present day. During the last major period of climate change continental glaciers covered a vast majority of what is now considered to be the country of Finland.

Already about 1920 million years ago, the present area of Eastern Finland was an ancient continental landmass covered by sedimentary rocks, with an ocean to the west of it. As a result of movements of the tectonic plates, a number of arcs of volcanic islands arose that were thrust eastwards by flows taking place within the earth, colliding with each other and eventually with the old Archean basement. By the time this collision phase had come to an end around 1870 million years ago, the area of Finland was occupied by a range of high mountains. The processes of folding that gave rise to these mountains had caused the volcanic islands, and their related sedimentary rocks to be piled up against the ancient continental mass in the east. This meant that some of the sedimentary rocks were thrust down deep into the earth’s crust, where they melted and then slowly crystallized to form various Igneous rocks.