m near the northern Gulf of Bothnia. Research history Discovery In 1887 Henrik Munthe was the first geologist to draw the conclusion that the Baltic Sea must once have been a freshwater lake. Munthe did so after finding fossils of the freshwater snail Ancylus fluviatilis in sediments. While these fossils were also found slightly before him by other geologists they thought they belonged to rivers, small former lakes or brackish water, failing thus to realize the existence of the lake. Geologists had until then subscribed to a simple scheme for the evolution of the Baltic Sea where small local ice-lakes were succeeded by the Yoldia Sea that then evolved directly to the Littorina Sea. The lake was named by Gerard De Geer in 1890 after the fossils. Controversy The lack of an obvious outlet of the lake led to intermittent debates involving not only Munthe and De Geer but also Ernst Antevs, Arvid Högbom, Axel Gavelin, N.O. Holst and H. Hedström. As the outlet was lacking there were doubts on whether Lake Vänern had been part of the lake or not, and on the position of its outlet or whether an outlet actually existed considering the lake could have been at sea level. Lennart von Post discovered by accident a small canyon near Degerfors in 1923 which he thought could be the elusive outlet. This came with time to be known as Svea River. Von Post collaborated initially with Munthe to study Svea River but their collaboration fell apart by 1927 over personal issues. The idea that the Svea River canyon was the outlet of the Ancylus Lake gradually lost ground by the works of Sten Florin, Astrid Cleve and Curt Fredén. In 1927 Cleve who was already "an outcast of the geological community" commented in an opinion piece in Svenska Dagbladet on a proposal of making Svea River a national monument. She supported the idea of protecting the area but criticized the established interpretation of Munthe and von Post. Munthe replied in Dagens Nyheter and the debate went over to a personal quarrel in two more newspaper letters in January 1928. Cleve outlined her ideas for Svea River and Ancylus Lake in detail in 1930 making an alternative and intricate theory involving tectonic movements. By 1946 she had changed mind as she then proposed an altogether different theory claiming the Svea River canyons and potholes formed by subglacial drainage