The physical contours of northern Europe, including the 338,145 sq.km. of land and water that constitute the present-day republic of Finland, were essentially shaped in the aftermath of the great Ice Age. The retreating mass of ice scoured the crystalline bedrock of the Fenno-Scandian shield, leaving in its wake thousands of shallow lakes, eskers and drumlins, and a deeply indented coastline that is still emerging from the sea as the land recovers from the tremendous compression of the glaciers. Only in the far north of Finland does the land rise above a thousand metres. To the east, the Maanselka ridge is a watershed for the rivers that run westwards into the Gulf of Bothnia and eastwards into the White Sea. The great lake systems of central and eastern Finland are separated from the coastal regions by a further series of ridges running in a south-eastward direction towards the south coast. Almost a quarter of the surface area of this inland region is covered by water, and a further 20 per cent is classified as wetland, mostly bogs and morasses. With all but a tiny tip of land lying north of the sixtieth parallel (Oslo and the Shetland Islands lie on this latitude, Stockholm slightly further south), Finland can claim to be the most northerly of all the countries of mainland Europe, stretching over a thousand kilometres from the northern shores of the Baltic towards the Arctic Sea.