1887

oa Annals of the Natal Museum - A review of Wilson's theory that the Last Interglacial ended with an ice-surge, and the South African evidence therefor

Volume 24, Issue 2
  • ISSN : 0304-0798

 

Abstract

A. T. Wilson proposed that the Last Interglacial ended with an ice-surge in Antarctica which would have raised ocean-level to about 15 m above present, and J. T. Hollin has collected evidence for a transgression higher than the peak of the interglacial under cold conditions, especially indicated by pollen, between Latitude 40° and 55° N. The surge was at first thought to have occurred at the end of Eem I about 120000 B.P., but Hollin now proposes the end of Eem II about 95000 B.P. This paper first discusses the sequence and chronology of the Last Interglacial, and then investigates geological and biological evidence for a marine transgression in the later part of the Eemian Interglacial in the South Cape, which faces Antarctica and so should be noticeably affected by ice-movements there. Around Port Elizabeth there was a transgression to + 18 m, leaving gravels which contain Late Acheulian artefacts, which according to recent evidence must be older than the Last Interglacial. After a regression, there was a second transgression to about +9 m, which has left estuarine beds with abundant warm-water and tropical molluscs, now extinct so far south; in places there are Middle Stone Age artefacts. Two sites have yielded specimens of this fauna at more than + 12 m. Racemisation-tests on molluscs from the +6-9 and the 12+ m beds show that the latter were considerably younger than the former, though it is not at present possible to obtain absolute dates by this method. The geological evidence is then reviewed for a transgression to + 12-+ 15 m around South Africa; molluscs are not indicative elsewhere. There is no sign of this transgression elsewhere in the South Cape and in Natal, little evidence at Langebaan Lagoon, a few doubtful sites in South West Africa (Namibia) and rather better evidence in Zululand. In general, the indications of such a transgression are poor; but it is not easy to explain the racemisation-figures from Port Elizabeth, and detailed investigation may reveal further sites where a short transgression took place, followed by a regression as expanding ice-sheets increased the albedo of the earth.

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/content/annals/24/2/AJA03040798_540
1981-10-01
2019-08-21

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