Base of Pleistocene Series and top of Pliocene Series is defined in stratotype section at Vrica, Calabria, southern Italy. Vrica section is located 4 km south of Crotone in Marchesato Peninsula. Pliocene-Pleistocene boundary placed at base of marine claystones conformably overlying sapropelic marker bed "e" in Vrica section. Several paleontologic events occur closely above and below boundary including last occurrence of calcareous nannoplankton DISCOASTER BROUWERI (below), last occurrences of foraminifer GLOBIGERINOIDES OBLIQUUS and nannoplankton CALCIDISCUS MACINTYREI (above), and first appearance of nannoplankton GEPHYROCAPSA OCEANICA (above). Normal polarity zone below marker bed "e" corresponds to Olduvai subchron. Bed "e" can be traced throughout outcrop and distinguished from overlying and underlying clay strata. Small geologic map of Vrica area (fig. 2). Figure 3 is measured section showing distribution of fossils. Age of boundary is about 1.64 Ma based on 1.67 Ma age for top of Olduvai subchron and sedimentation rate of 310 mm per thousand years for interval between top of Olduvai and top of bed "e."

Source: GNU records (USGS DDS-6; Denver GNULEX).

Pliocene-Pleistocene boundary placed at 1,650,000 yrs. This age was assigned provisionally at Vrica, Italy. However, "no stratigraphic boundary of regional extent of that age... has been identified in the U.S.A."

Source: GNU records (USGS DDS-6; Denver GNULEX).