The results of a detailed magnetostratigraphic and biostratigraphic study of late Pliocene to early Pleistocene marine
marl sequences from the Monte Singa and Crotone areas in Calabria, Italy are presented.
The magnetostratigraphy from the Monte Singa sequence ranges from below the Gauss/Matuyama boundary up to and
including the lower Olduvai boundary. Normal polarities at a level corresponding to isotope stage 81 most probably
represent the R~union subchron. From the lower Olduvai boundary upward, a reliable magnetostratigraphy could not be
established due to increased weathering of the marls, resulting in mainly secondary magnetizations.
The magnetostratigraphy from the composite sequence of the Crotone area belongs to a large part of the Matuyama
Chron and includes the Olduvai subchron. The position of the lower and upper boundaries of the Olduvai subzone could be
established more precisely than from earlier results. Moreover, the upper boundary of the Olduvai subzone poses an
ambiguity: a relatively long normal polarity interval representing the main Olduvai subchron and corresponding to a
duration of 115 ka is followed by a short (30 ka) reversed subchron and the short (15 ka) normal Vrica subchron. Another
option, and more in accordance with the duration of the Olduvai subchron in literature, would be to consider the complete
N-R-N polarity succession with a total duration of 160 ka as representing the Olduvai subchron, implying that this Olduvai
subchron has a short reversed interval in its upper part.
Linear interpolation and extrapolation yield ages for the most important late Pliocene-early Pleistocene biostratigraphic
datum levels. An age of 1.69 Ma is found for the Pliocene-Pleistocene boundary, using the conventional polarity time scale
dated with radiometric results. However Hilgen [1], in correlating the sapropel groups and patterns to the precession curve
of the Earth's orbit, obtained significantly different ages for the polarity transitions of the present study. According to this
astronomically calibrated polarity time scale, the age of the Pliocene-Pleistocene boundary is 1.81 Ma
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