In order to enhance the reliability and precision of the ecostratigraphy of the Quaternary of the Oslo Fjord area, an analysis of selected faunas has been made, for the purpose of determining their relationship to Thorson's Arctic-animal communities and their trophic structure, and especially of reconstructing the original biocoenosis from the observed taphocoenosis. The “noise” due to ice-rafted fossils has been estimated, and it is concluded that epifaunas may appear “warmer” than infaunas from the same environment, when interpreted by conventional methods. Discrepancies in the distribution of some species are attributed partly to the comparatively low latitude of the Oslo Fjord area, and partly to our incomplete knowledge of parts of the Recent faunas. The tentative, preliminary model indicates that the hydrological conditions changed from those of an open, ice-margin shelf-up to and during the Younger Dryas time-to those of an Arctic fjord, after the ice had retreated from the Ra line.