Salpausselkä

thumb|330px|Salpausselkä ridge system thumb|330px|Animation about the formation of Salpauselkä Salpausselkä (; "Bar Ridge") is an extensive ridge system left by the ice age in Southern Finland. It is a large terminal moraine formation that formed in front of the Baltic ice lake during the Younger Dryas period about 12,250–10,400 years ago. All together the formation is close to from end to end, and the ridges can be as tall as in some places.

It runs from Hanko hundreds of kilometers to the east. It traps the extensive river and lake systems of Central Finland known as Finnish Lakeland (, "Lake Finland") and forces the water to flow through few breaches in the ridge. The Vuoksi River flows from lake Saimaa into Lake Ladoga () in Russia. From there the water subsequently flows through river Neva into the Gulf of Finland, bypassing the Salpausselkä. The Kymi River flows from Päijänne into the Gulf of Finland. An artificial breach from the Lakeland is the Saimaa Canal, from Saimaa at Lappeenranta into the Gulf of Finland at Vyborg.