Ancylus Lake

Ancylus Lake is a name given by geologists to the body of fresh water that replaced the Yoldia Sea after the latter had been severed from its saline intake across central Sweden (with the eastern end of the channel near present Stockholm) by the isostatic rise of south Scandinavian landforms. The dates are approximately 9500–8000 BP calibrated, during the full Boreal period. The lake became the Littorina Sea when rising oceanic levels broke through the Great Belt.

The lake was named by Gerard de Geer after Ancylus fluviatilis, a gastropod found in its sediments.

Description

The elevation of southern Sweden did not entirely block the flow across central Sweden. Some egress continued from the lake through the Göta and Steinselva rivers, which exit Vänern to the Kattegat. Salt water did not enter the lake, however, which became entirely fresh as the lake rose above sea level. The date at which the flow was certainly blocked is about 8000 BP, when nearby Lake Vättern (part of the waterway system) became severed from Ancylus Lake.