Sedimentation and late Quaternary evolution. Geologian tutkimuskeskus, Tutkimusraportti - Geological Survey of Finland, Report of Investigation 143.
Diatoms represent gradual oligotrofication of water.
Changes in climate and vegetation, e.g. paludification of the environment, caused minor changes in the properties of gyttja. The sediments in depressions underwent anaerobic decomposition under oligotrophic conditions, resulting in the formation of sulphide-bearing bands.