| Summary: | The Utrecht working group taking part in the I.G.C.P. project no. 1, "Accuracy in time", received its initial funds in the middle of 1975. The group hastened to collect a first series of samples with which it could begin its research. The marly clays of the selected sections Apostoli and Potamidha 1 cover the major part of the marine Middle-Upper Miocene of Crete (Freudenthal, 1969; Meulenkamp, 1969). The corresponding time span, estimated to be some five million years, was thought to be sufficiently long to permit a detailed study of the evolution of the benthonic foraminiferal lineages of Planorbulinella and Uvigerina and an evaluation of the entries of some planktonic marker species. Moreover, the facies of the deposits was considered suitable for magnetostratigraphic research. The biostratigraphers sampled both sections closely with equal spacing, each sample covering an interval of five to ten centimetres. The magnetostratigraphers had their own sampling method; the position of their cores was calibrated in the field with the sampling spots of the biostratigraphers. In some parallel sections layers with volcanic ash were sampled for radiometric dating. It soon appeared that the bentonite samples were unsuitable, at best they yielded untrustworthy results. Next, the entire Apostoli section was found to give normal polarity for all samples after demagnetization, evidently the sandy-silty character of the clays of this section had provided an opportunity for a subrecent destruction of the original magnetisation in the expected reversed polarity intervals. Since the Potamidha section appeared more suitable, efforts on the Apostoli section were stopped with the exception of the investigation of the Uvigerina lineage (Thomas, in preparation). The gathering of the faunal and floral composition data on the Potamidha samples was started and the usual Utrecht counting procedure was applied, i.e. counting up to 200 specimens for benthonic foraminifera, for planktonic foraminifera and for calcareous nannofossils. While ...
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