The universal geography : earth and its inhabitants

22 THE NORTH-EAST ATLANTIC.water-line is often displaced several hundred yards according to the direction ofthe wind-;.Like all land-locked hasins, the Baltic is much influenced by atmosphericchanges, producing the so-called seiches, analogous to those of Lakes Neuchateland Geneva. Schulten was the first to explain these phenomena, showing theircoincidence with the movements of the barometer. The waters rise in proportionto the depression of the air, often attaining an elevation of 3 to 6 feet.This happens most frequently in spring and autumn, but the phenomenon takesplace also in winter beneath the frozen surface, which is then upheaved and evenburst asunder with a terrific report by the force of the rising waters. Otherand not yet explained movements also occur, though at long intervals, in theBaltic. "We read that at times the sea roars in fine weather, rises, and floods theshores, as in 1779, when it deluged the town of Leba, in East Pomerania, rising1G feet above its usual level. These phenomena are called " sea-bears," notperhaps so much on account of the accompanying noises as of their analogy tothe " bores " of marine estuaries. Formerly the process was reversed, the seareceding without any apparent cause to a great distance along the flat shores ofthe Baltic *It is certain that during recent geological epochs the Baltic has greatlychanged in form, and observations now being made show that it is still changing.It roughly occupies a long valley parallel to the Scandinavian table-land, but itsoutlet towards the ocean has been shifted. The channels of the Sound and theBelts have been opened through rocks which at one time formed continuous land.At various points along these straits the opposite sides are seen to correspond,showing that they have been forced open by the action of the water. Themarine deposits left in the interior of Sweden also prove that the Baltic communicateddirectly with the Kattegat through the great Lakes Wenern andWettern, at present connected by the Goteborg Canal. At considerable depthsin these lakes the naturalist Loven has fished up various species of arctic marinecrustacea belonging, some to the Polar Sea, others to the Gulf of Bothnia.!presence of these animals shows that in the glacial period the Swedish lakescommunicated with the Baltic, and were not sweet, but vast salt straits windingfrom sea to sea. Owing to the upheaval of the Scandinavian peninsula which isstill going on, they were transferred to land-locked basins, and their waters, continuallyfed by rain and river, lost all their saline character. Most of theirfauna perished, but some became acclimatized, and it is these that are now discoveredat the lowest depths of the Swedish lakes.?In animal species the Baltic is one of the poorest seas, the mingling ofsweet and salt waters and the great variability of the yearly temperature beingunfavourable to the development of life.TheAccording to Nilsson there are not thirtyspecies of salt-water fishes, and the only cetacea are the seal and dolphin. All* Globus, No. 22, 1S72.t M&moires