Ancylus Lake
The Ancylus Lake was a lake in north-eastern Europe which existed approximately at the site of today's Baltic Sea about 9500-8000 years ago. It is named after the index fossil Ancylus fluviatilis, a freshwater snail.
Baltic Ice Lake
About 14,000 years ago, the two or three kilometers thick Scandinavian ice sheet began to melt off the Weichsel ice age slowly. At this time a lake, the Baltic Ice Lake developed behind the Ice Barrier from the meltwater.
About 10,000 years ago the defrost ice barrier between the ocean and Ice Lake released the Swedish Central Valley, which brought the Baltic Ice Lake to sail.
Yoldia sea
Due to the eustatic sea-level rise caused by the melting of glaciers, was for about 300 years, a connection to the North Sea and it penetrated salt water in the Baltic Sea area a. Through this exchange of water mussel Yoldia arctica ( Portlandia arctica now ) came into that now brackish to salty waters, which earned him the name Yoldia sea.
Ancylus Lake
The Relief of the Scandinavian mainland by the weight of the ice led to an isostatic land uplift of up to nine millimeters / year, which is still ongoing today. Through this land uplift, the Central Swedish connection to the sea closed again about 9500 years ago. It developed in the area of today's Baltic Sea a second time an inland lake, the Ancylus Lake. It is named after the river cap screw ( Ancylus fluviatilis), which spread in the freshwater lake. The Ancylus Lake dewatered over a river in the area of the Great Belt.
Littorinameer
As rising temperatures melt the ice could be continued, the water level of the ocean to rise. Only a small isthmus finally severed the mainly existing at -30 meters NN North Sea from which melt water Ancylus Lake.
In conjunction with movements of the earth's surface flooded the North Sea and Denmark interrupted about 8500-8000 years ago the land bridge Denmark Scandinavia. Water from the North Sea flowed into the Ancylus Lake, so that initially increased in the western part, and later also in the eastern part of the salt content. It formed the Littorinameer, named after the snail Littorina littorea beach.