The stratigraphic distribution of Pliocene molluscs from deposits of the northern Peel district in The Netherlands

Fifteen well-borings in a fault block of the Peel-horst yielded 132 samples of fossil shellbearing sediment layers. A total of 177 species was identified, of which 88 are gastropods, 86 bivalves and 3 scaphopods. Two biozones could be distinguished, an upper zone, here called the Cerastoderma edule hostiei range-zone, and a lower zone, here called the Pseudamussium gerardi range-zone. The stratigraphic distribution of the species is shown in table 2, as are the thickness and depth of the zones (table 1). An interzone of 1-2.5 m is present. Two small species, Semierycina kautskyi and Cingula inusitata, show their greatest concentration here. Table 3 proposes a correlation with the marine Pliocene of Belgium. The Kattendijkien appears to be absent in the area investigated. Glibert (1958) records a number of species from the Belgian part of this deposit and Janssen, Peeters & Van der Slik (1984) deport these from the Dutch beaches and estuaries. Only two of the species not mentioned by the above authors from more recent deposits, have been found in the Peel material, viz., Pygocardia rustica tumida and Philine quadrata, the latter still occurring in the North Sea.