A brief historical review of the stratigraphy is given. Indicated is what was understood as “Hemmoor Stufe” and “Reinbek Stufe”, of the latter the subdivision in “Unterstufen” is given. The basal strata of the Upper Miocene may have been deposited on a very shallow flat, causing the strandings of many whales. At the base of the miocene deposits in the region studied always a layer with rounded phosphorites and worn shark-teeth is found. Arguments for regarding Hemmoor and Reinbek Stufe as different facies of the same transgression are given by Boekschoten (1969b). A survey is given of the research of the Miocene in the Achterhoek and adjacent parts. A recent research of the differences between biocoenosis and thanatocoenosis of the Ria de Arosa (Spain) is dealt with; transport of dead material is mentioned. In addition the mistakes caused by the drilling — methods used are given. An analysis is given of the several proposed methods for counting molluscs. The method used for this research is given with arguments concerning the deviations. Indicated is the accuracy of the counting. The apex of a gastropod shell counts for one specimen, the umbo of a bivalve shell for half a specimen. Species for which another part is regarded as characteristic are mentioned, complete with the reasons. A counting-table is given for possible later statistic treatment.