Plant microfossil samples from drillholes near Frankton, through some 700 ft of pumiceous and non-pumiceous sand, silt, clay and lignitic beds, range in age from Waitotaran (Upper Pliocene) to Upper Pleistocene or younger. The Plio-Pleistocene (Waitotaran-Nukumaruan) boundary is clearly shown where a sub-tropical Waitotaran vegetation is replaced by a Lower Nukumaruan vegetation, indicating a climate cooler than that of the present day. A brief comparison is made with similar Plio-Pleistocene sequences elsewhere in New Zealand.