ABSTRACT
Pollen bearing deposits of the southwestern Cape have been studied. In the oldest sections of the cores different types of Tertiary vegetation are represented since the Late Oligocene or Early Miocene until their ultimate extinction. The sporomorphae of the younger parts of the deposits are typical of the type of vegetation which exists in these regions at present and are considered to be of Quaternary age. Correlations with recent oceanographic data (Siesser, this volume) suggest that the Tertiary vegetation was probably eliminated in early Late Miocene times. The cold Benguela Current then originated together with the new climatic system for the sub-continent which is characterised by winter rainfall and dry summers. Data on the evolution of the Antarctic ice sheet (Mercer, this volume) could however point to a later extermination of this Tertiary vegetation during the Late Miocene to Early Pliocene.
Palm-dominated sub-tropical to tropical vegetation alternated with conifer forests during the Tertiary at the Cape which may be of significance with regard to the marked temperature oscillations of the Miocene (Mercer, this volume). Some of the Tertiary pollen types are of considerable botanical interest as they shed light on distribution patterns which could have existed before the separation of Africa from Antarctica between the Upper Jurassic and Lower Cretaceous.
Some evidence exists for the progressive aridification of the whole continent from Pliocene times onward and in particular the development of extreme aridity along the southwest coast. The results of research in different disciplines strongly indicate that the evolution of the Antarctic ice sheet and the subsequent Quaternary glaciations had a profound influence on these changes in climate and biogeography.
