Ostrobothnia (historical Province) - Geography

Geography

Ostrobothnia can be roughly said to be divided from Southern parts of Finland by the watershed Suomenselkä, a glacial formation on the Northern part of which the waters flow to Merenkurkku or Perämeri and on the Southern part to Gulf of Finland or to Selkämeri. In the East, the historical Ostrobothnia is bordered by Russian Karelia on Maanselkä watershed, which divides the estuaries of Oulujoki and Iijoki from the estuaries of rivers flowing to White Sea. In the North, the historical borders of Ostrobothnia towards Västerbotten and Laponia are somewhat undefined, partly because the permanently fixed inhabitation was a relatively new phenomenon at the time of the introduction of county system, which replaced the older provincial divisions. On the coast, the historical border ran somewhere between the Torniojoki and Iijoki, without any formal definition in the inland. However, the watershed between Kemijoki, Iijoki and Olhavajoki estuaries may serve as a definition of the border between Laponia and Ostrobothnia.

The stereotypical topographic feature of Ostrbothnia is the coastal plain North of Suomenselkä, in the nowaday regions of Ostrobothnia, Southern Ostrobothnia and Central Ostrobothnia. It is glacial (Weichsel glaciation) seabed, its topography flat with few hills, and characterized by South-East to North-West running rivers, which were formed by waters at the end of the glaciation. Due to the depression caused by the ice masses which lay on the top of the ground, the ground level is still rising, at a rate of circa 9 mm per annum. Due to the very flat topography, this causes the Gulf of Bothnia to withdraw several kilometers per century and has historically caused great problems to navigation and to the harbours of the coastal cities of the region.

As another result of the glaciation, all the numerous rivers of the region run from South East towards North West. The bedrock in the area, where exposed, features SE-NW oriented lines carved by rocks which were pushed South-East by the advancing ice mass during the glaciation. To the end of the ice age, the ice mass melted away, leaving its marks all over the country: huge boulders (glacial erratics), carved lines on the bedrock, sand pits etc.

On the coast of Northern Ostrobothnia, the topography remains flat, but instead of fields of Central and Southern Ostrobothnia, the land is largely covered with marsh. Towards inland, the terrain becomes more varied. Here, the taiga and hills dominate the landscape, with an occasional village or small town. The most important terrain feature in inland Ostrobothnia is the large Oulujärvi, a lake of 887 km2. Most of the activity in the region of Kainuu, is centered to the municipalities around this lake, which is connected to sea via Oulujoki. North of Kainuu, Koillismaa forms one of the most rural and poorest sub-regions in Finland.