Iso Kaivoneva is a raised bog that has formed on the side of the Karhukangas glacial river formation. It is located on top of thick layers of gravel and sand. The waters of the bog cannot soak into the gravel layers, because the surface of Karhukangas has a thin layer of dense till. This layer, known as hill clay, covers large areas around Lauhanvuori, and enables ponds and swamps to form in places where water would not otherwise remain. The water accumulated on the surface compacted by the till is perched ground water, which is separate from the actual groundwater.