New Zealand pPiocene and Pleistocene climates; evidence from fossil floras
This paper (to be published in full in N Z.J. Sci.Tech) discusses plant fossils from Upper Tertiary and Pleistocene beds and shows that paleobotanical evidence supports Fleming's (1953) suggestion that the Nukumaruan and Castlecliffian stages, at present considered to be Pliocene, should be included in the Pleistocene. The significant points are, that Nukumaruan and younger floras lack many species that are important in underlying Tertiary beds, and that some Nukumaruan floras indicate markedly cooler climates.
Microfloras of six Upper Miocene and six Pliocene beds, covering a wide geographic range, show a reasonably constant assemblage of spores and pollen grains attributable to forest species. Particularly important is Nothofagus cranwellae Couper, which first appears in the Eocene in New Zealand; the only living species of Nothofagus with similar pollen grains are those large-leaved ones recently discovered in New Guinea and New Caledonia. Another species which occurs first in Eocene beds is important here also, namely Triorites harrisii Couper, belonging to either Betulaceae or Casuarinaceae; neither of these families has reccnt representatives in New Zealand. Conifers, treeferns, and beeches with pollen grains like those of N. fusca (a group including all present-day New Zealand Nothofagus except N. menziesii) are comparatively minor elements in all these floras. Plant macrofossils from the upper Miocene (Great Barrier Island and Kaikorai Valley, Dunedin) and from the lower Pliocene (Upper Rangitikei Valley) include many extinct species, and, in particular, are characterized by large Nothofagus leaves.