Swartkrans Cave
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Swartkrans is a fossil hominin-bearinig cave situated approximately 1km to the west-northwest of the well known fossil site of Sterkfontein in the Cradle of Humankind World Heritage Site.
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History of Investigations
The earliest palaeontological work at Swartkrans dates to 1948 when Robert Broom began collecting fossils at the request of the University of California African Expedition.[1] Broom worked at the site until his death in 1951, and he, and later John Robinson, recovered a large amount of hominin material. This material included the first recorded occurrence of more than one hominin species in a single deposit: Paranthropus robustus alongside a type of early Homo [1]. Robinson continued his work at Swartkrans until 1953, when the site was abandoned [2]. In 1965, C.K. Brain of the Transvaal Museum resumed work at the site, work that continued for the next 21 years[2]. Brain’s excavations involved sampling mining displaced breccia blocks, as well as the first in situ excavations at the site[3]. . The meticulous nature of the provenience data that he recorded (a level far beyond what was generally accepted as the norm at the time) allowed a workable Geographical Information System (GIS) based 3-D map of in situ deposits to be reconstructed [4]. The faunal assemblage that Brain was able to extract from this site was instrumental in his re-interpretation of the way bones accumulate in the fossil caves, detailed in his (1981) book, titled The Hunters or the Hunted? [3]. Other notable discoveries at Swartkrans included evidence of the earliest controlled use of fire [5], as well as a number of bone tools that are thought to be termite mound digging implements [6].
Geology of the site
Brain (1958) provided the first comprehensive geological study and developed the first model for the stratigraphy of the site[7]. Work continued at Swartkrans for the following two decades and in the mid 1970s Butzer advanced on Brain’s earlier work and formally defined the Swartkrans Formation, with two component members[3]. It was not, however, until 1979, when Brain began in situ excavations of the sedimentary strata of Members 1, 2 and 3, that meaningful geological data was generated[4]. His efforts provided a number of insights into the complexity and nature of the fill, and led to the development of a five-member stratigraphy for the site, with each member separated from its older counterpart by an erosional discontinuity (an period of time between the deposition events) [8].
Geological Members
There have been five geological “Members” identified at Swartkrans. Member 1 represents the early stage of fill. Member 2 is believed to be separated from Member 1 by a period of erosion. It is believed to have been deposited down a shaft near the center of the cave which then led to the infilling by reddish brown sand and clasts of dolomite and speleothems. The Member 2 sediments are highly fossiliferous, and yield a diverse mammalian fauna including hominins. This unit has also yielded artifacts of a Developed Oldowan or Early Acheulean industry, as well as bone tools.[3] [7] [8] Member 3 was excavated between 1982 and 1986. This infill was formed in a deep gully eroded into Member 1 and 2 deposits. It is mostly noted for the fact that it contains burnt bone, the spatial and temporal distribution of which is suggestive of the controlled use of fire in the cave entrance[8] [9]. This discovery therefore marks the earliest evidence of the controlled use of fire yet identified [2] Member 4 is a largely un-calcified deposit that occupies the northeast corner of the cave, and was deposited under an overhanging roof remnant [10]. It contains abundant Middle Stone Age artifacts but has not yet been excavated[10]. Member 5 is much younger than Member 4, from which it is separated by an erosional disconformity. It forms a 4m thick, lightly calcified deposit on the northwest side of the cave, and has yielded abundant remains of the extinct springbok Antidorcas bondi, from which a radiocarbon age of 11 thousand years (Kya) has been obtained [8].
Age of the deposits
It is difficult to absolutely date the age of South African cave sites nevertheless numerous studies have suggested an age range of between approximately 1 million and 1.5 million years for Members 1 through 3 [2].
Fossil hominin species from Swartkrans
- Paranthropus robustus
- Homo ergaster
Important fossil specimens discovered at Swartkrans
- Sk 48 - P. robustus skull
- Sk 847 – H. ergaster face
References
- ↑ 1.0 1.1 R. Broom and J.T. Robinson. (1952). Swartkrans ape-man Paranthropus crassidens. Transvaal Museum Memoir No. 6..
- ↑ 2.0 2.1 2.2 2.3 Hilton Barber, B. and Berger, L.R. (2001). Field Guide to the Cradle of Humankind. Struik.
- ↑ 3.0 3.1 3.2 3.3 C.K. Brain (1981). The Hunters or the Hunted?. University of Chicago Press.
- ↑ 4.0 4.1 Nigro et al. (2003). Developing a Geographic Information System (GIS) for Mapping and Analyzing Fossil Deposits at Swartkrans, Gauteng Province, South Africa. J Arch Sci.
- ↑ L.R. Berger (2005). Working and Guiding in the Cradle of Humankind. Prime Origins.
- ↑ L. Backwell and F. D’Errico (2001). Evidence of termite foraging by Swartkrans early hominids.. Proc Nat Acad Sci (USA).
- ↑ 7.0 7.1 C.K. Brain (1958). The Transvaal Ape-man – bearing cave deposits. Transvaal Museum Memoir No. 11..
- ↑ 8.0 8.1 8.2 8.3 C.K. Brain (1993). . Structure and stratigraphy of the Swartkrans cave in the light of new excavations. In Brain CK editor. Swartkrans: a cave’s chronicle of early man. Transvaal Museum Monograph No. 8..
- ↑
- ↑ 10.0 10.1 T. Partridge (2000). . Hominid-bearing cave and tufa deposits. In: Partridge TC, Maud RR editors. The Cenozoic of southern Africa.. Oxford Monographs on Geology and Geophysics.
