Geology of Finland subsequent uplift and erosion would have eroded all of these sediments. In Finland, Caledonian nappes overlie shield rocks of Archean age. Despite occurring in about the same area the Scandinavian Caledonides and the modern Scandinavian Mountains are unrelated. The ice sheet that covered Finland intermittently during the Quaternary grew out from the Scandinavian Mountains. By some estimates the Quaternary glaciers eroded away on average 25 m of rock in Finland, with the degree of erosion being highly variable. Some of the material eroded in Finland has ended up in Germany, Poland, Russia and the Baltic states. Ground till left by
Finland–Russia border 2020. However, Lieutenant-General Vladimir Streltsov, deputy head of the Russian border service, noted that electronic surveillance will never replace the human element. The border can be crossed only at official checkpoints, and at least one visa is required for most people. Major border checkpoints are found in Vaalimaa and Nuijamaa, where customs services on both sides inspect and levy fees on imported goods. The northern endpoint of the border between Norway, Finland, and Russia form a tripoint marked by Treriksrøysa, a stone cairn near Muotkavaara (). On the south, the boundary is on the shore of Gulf of Finland, in