Late Cenozoic Paleoclimates of the Gaap Escarpment, Kalahari margin, South Africa

Abstract

The Gaap Escarpment is a dolomite cuesta demarcating the southeast margin of the Kalahari. Since Miocene-Pliocene times, thick masses of lime tufa have repeatedly accumulated at several points along this escarpment, and four regional sequences are described. These allow discrimination of six major depositional complexes, commonly characterized by basal cryoclastic breccias or coarse conglomerates that reflect frost shattering and torrential runoff, followed by sheets and lobes of tufa generated in an environment substantially wetter than today. A chronostratigraphy for the last 30,000 yr is provided by 14C dating, with direct or indirect correlations to the Vaal River sequence. The regional stratigraphy as well as faunal dating indicate an early Pleistocene age for Australopithecus africanus at Taung. Repeated episodes of protracted cold or wetter climate or both begin in terminal Miocene times, and the last Pleistocene cold-moist interval began after 35,000 yr B.P. and ended 14,000 yr B.P. Early and late Holocene times were mainly wetter, whereas the middle Holocene was drier than today. The paleoclimatic sequence differs from that of the southern and southwestern Cape or that of East Africa, but close parallels are evident throughout the lower Vaal Basin and the southern Kalahari. The tufa cycles provide a unique, 5,000,000-yr record of climatic variation in the Kalahari summer-rainfall belt that can be related to complex anomalies of the general atmospheric circulation.

The application of a present-day climatic model to the late quaternary in southern Africa

“…Such appears to have been the case for the northern Kalahari (Street and Grove, 1976;Grey and Cooke, 1977;Heine, 1978;Cooke, 1980;Cooke and Heine, 1983;Helgren and Brooks, 1983;Helgren, 1984), the south-western Kalahari (Heine, 1981(Heine, , 1982, the central Namib (Vogel and Visser, 1981 ;Lancaster, 1983;Vogel, 1983 ;Ward et al, 1983 ;Heine and Geyh, 1984), the northern and central Transvaal (Marker, 1974), the central interior (Butzer, Stuckenrath et al, 1978;Butzer, Fock et al, 1979;Butzer, 1984aButzer, , 1984b, the Karoo (Beaumont, 1986) and the south-western Cape (Butzer, 1984a). Avery (1979), Beaumont et al (1984, Butzer (1973a, 1984a, 1984b, Butzer, Fock et al (1973, Butzer and Helgren (1972), Butzer, Stuckenrathet al (1978), Coetzee (1967), Cooke (1975Cooke ( , 1980Cooke ( , 1984, Cooke and Heine (1983), Deacon and Brooker (1976), Deacon, H. J. et aL (1984), Deacon, Scholtz and Daitz (1983), , , Grey and Cooke (1977), Heine (1978Heine ( , 1981Heine ( , 1982, …”

A critique of the chronometric evidence for hominid fossils: I. Africa and the Near East 500–50ka

“…The cave was formed in the Oxland Tufa, the youngest parts of which are dated to 230 ± 17 ka by uranium-thorium (Vogel and Partridge, 1984). Butzer et al (1978) stated that the sediments are older than a widespread manganiferous patina. This patina is older than the Blue Pool Tufa II, which has a minimum radiocarbon date of 15,980 ± 230 BP, and younger than the Blue Pool Tufa I, which has uranium-thorium ages ranging from 30 ± 3 to 103 ± 6 ka (Vogel and Partridge, 1984).…”

“…The patina is also younger than a travertine at Witkrans Cave dated by radiocarbon to a minimum of 33,150 ± 2,500 BP (Berger and Libby, 1966;Clark, 1971). Butzer et al (1978) argued that the dissolution of Equus Cave was contemporary with the formation of the Blue Pool Tufa I. The human remains are thus broadly constrained between a calibrated radiocarbon age of 17,600-16,850 BC and the formation of the Oxland Tufa at 230 ± 17 ka and most likely belong to the period between 103 ± 6 ka and 30 ± 3 ka.…”

50,000 years of vegetation and climate change in the southern Namib Desert, Pella, South Africa

“…van Zinderen Bakker, 1976), it has also been suggested that more extensive Northern Hemisphere ice sheets would have resulted in a southward displacement of the African rainbelt (cf. the Intertropical Convergence Zone (ITCZ)), bringing more tropical rain to the region during the summer (Butzer, 1984;Butzer et al, 1978;Lancaster, 1979;Lewis et al, 2010).…”