Tertiary environmental changes along the south-western African coast
Date
1980
Authors
Coetzee, J. A.
Journal Title
Journal ISSN
Volume Title
Publisher
Bernard Price Institute for Palaeontological Research
Abstract
Evidence for major vegetation and climatic changes during the Tertiary in the south-western
Cape has been obtained from a number of sites. The palynomorph assemblages indicate
in general an alternation of relatively cool temperate forests with two periods of subtropical - tropical palm-dominated vegetation from the Late Oligocene/ Early Miocene to the Pliocene
when many of the taxa became extinct. Subsequently, strong development of macchia vegetation
took place. These changes can be correlated with some palaeogeographic data and the
major temperature changes of the Southern Ocean indicated in the palaeotemperature curve
of Shackleton and Kennett (1975) which reflects the longterm progressive cooling of the earth
since the Eocene/Oligocene boundary. The two subtropical- tropical periods can probably
be related to the respective Early and Middle Miocene pan-African faunas of Arrisdrift and
Luderitz and could coincide with the two warmest periods of the Miocene at 19 My and
14 My ago. The end of the Miocene witnessed the maximum build-up of the Antarctic icesheet
and the substantial increase of the upwelling in the Benguela Current. This resulted in
the initiation of the aridification of the present Namib desert, the extermination of the palm
vegetation and the provincialism of the coastal molluscs. The important drop in temperature
which reached its maximum about 3,5 My ago in the Pliocene could have exterminated the
surviving elements of the last of the temperate Tertiary forests. The progressive aridity of the
continent resulted in the spread of savannas, the evolution of the Alcelaphini and Antelopini
and the change to regional vertebrate faunas. The increasing summer aridity in the southwestern
Cape led to the strong development of the macchia vegetation.
Description
Main article
Keywords
cimatic change; Tertiary; Africa
Citation
None