The Cradle of Humankind Site
comprises a strip of a dozen dolomitic limestone caves containing the
fossillised remains of ancient forms of animals, plants and most importantly,
hominids. The dolomite in which the caves formed, started out as coral reefs
growing in a worm shallow sea about 2.3 billion years ago.
The Cradle of Humankind site lies mainly in the Gauteng province with a small extension into the neighboring North West Province, and covers 47 000 hectares of land mostly privately owned. The Cradle of Humankind Site comprises a strip of a dozen dolomitic limestone caves containing the fossillised remains of ancient forms of animals, plants and most importantly, hominids. The dolomite in which the caves formed, started out as coral reefs growing in a worm shallow sea about 2.3 billion years ago.
As the reefs died off they were transformed into limestone which some time later was converted into dolomite. Millions of years later after the sea had receded, slightly acidic groundwater began to dissolve out calcium carbonate from the dolomite to form underground caverns. Over time the water table dropped and the underground caverns were exposed to the air. The percolation of acidic water through the dolomite also dissolved calcium carbonates out of the rock into the caverns, which formed stalactites, stalagmites and other crystalline structures. Continued erosion on the earth's surface and dissolution of the dolomite eventually resulted in shafts or avens forming between the surface of the earth and the caverns below. Bones, stones and plants washed down these shafts into the caves; and animals and hominids fell into the caves, became trapped and died. The bone and plant remains became fossilized and along with various stones and pebbles became cemented in a hard mixture called breccia.
At least seven of the twelve sites have yielded hominid remains. In fact, together these cave sites have produced over 850 hominid fossil remains, so that to date they represent one of the world's richest concentrations of fossil hominid bearing sites. The scientific value of this area lies in the fact that these sites provide us with a window into the past, to a time when our earliest ancestors were evolving and changing. Scientists have long accepted that all humans had their origins in Africa.
Through the use of biochemical evidence they have argued that the split of the human lineage (Hominidae) from that of the African apes took place around 5-6 million years ago. The study of hominid fossils from sites in Africa thus enables scientists to understand how these hominids have changed and diversified since then.
The Sterkfontein Caves are located within the
Isaac Edwin Stegmann Reserve about 10km from Krugersdorp. These caves were donated to the University of
Witwatersrand by the Stegmann family. A section of the caves is open to the
public, and there is a gravel platform from which the public can view the
excavation site. Other facilities include a tea-room and small museum in which
information about significant findings are on display.
Right from the start the caves proved rich in hominids. In 1936 the Sterkfontein caves produced the first adult australopithecine. In 1947 the almost complete skull of an adult female Australopithecus africanus was found. Initially named Plesianthropus transvaalensis ("near-man" of the Transvaal), which inspired the nickname 'Mrs. Ples'.
'Mrs. Ples' is estimated to be between 2.8 and 2.6 million years old and ranks high on the long list of australopithecine discoveries for which Sterkfontein is now famous. The world's longest sustained excavation ever carried out at an ancient hominid site was started in 1966 and continues today. A further 500 hominid specimens have been recovered, making Sterkfonteln the world's richest hominid site. The site is also renowned for studies carried out on fossilised fauna, wood and stone tools which were made, used and discarded by hominids In the past.
The fossil remains from Broom's excavations are housed In the Transvaal Museum (Northern Flagship Institution), Pretoria, while the remains from 1966 onwards are housed at the University of Witwatersrand, Johannesburg.
Swartkrans is located about 1.5km north-west of the Sterkfontein Caves and is owned by the University of the Witwatersrand. Drs. Broom and Robinson carried out the first scientific excavations at Swartkrans towards the end of 1948. To date, more than 200 hominid specimens, mostly attributable to Paranthropus (Australopithecus) robustus, numerous animal remains and stone and bone tools have been recovered from this site. Apart from these robust hominids, however, Swartkrans was also the first site In Africa to yield remains of Homo ergaster. Homo sapiens, in Africa, is thought to be responsible for the stone tools and possibly for the use of controlled fire at Swartkrans. Deposits at Swartkrans date between 1.8 and 1 million years ago. Hominid and faunal specimens from Swartkrans are housed at the Transvaal Museum (Northern Flagship Institution)
This site Is located about 1 .1 km to the north-west of the Kromdraai store on a steep hillside overlooking the BloubankspruIt. No recent excavations have been carried out, however there It is a possibility that hominid remains may be found If excavations are resumed.
Plover's Lake Is located north-east of the Sterkfonteln Caves, about 2.5km from the Kromdraai -Broederstroom road. Excavations have been carried out by Dr. Francis Thackeray of the Transvaal Museum (Northern Flagship Institution) In association with scientists from Washington University. The ancient cave roof has disintegrated as a result of erosion leaving" exposed calcified sediments rich with fossils. The site has yielded abundant faunal remains Including antelope, extinct zebra and a leopard lair.
The Wonder Cave Is located about 2.5 km from the Kromdraai. The enormous cave chamber with a volume of 46 OOOm Is believed to be 2.2 million years old. This cave has the best example in the region of a relatively young taluscone (a few thousand years old) which helps us understand how the older caves in the area were filled in. Wonder Cave contains drip stone formations as beautiful as those in the Cango Caves. It also has a resident bat population. Hourly tours are conducted by on well-lit pathways where no crawling is necessary.
The site is located 1.6 km to the west of the Wonder Cave. It is one of the most recent fossil hominid sites to be discovered, and is already the 3rd richest fossil hominid site. 75 specimens of Paranthropus (Australopithecus) robustus and 5 specimens of Homo sapiens have been unearthed together with a substantial faunal sample.
The site, Kromdraai, is situated about 1 .5 km north of the Sterkfontein caves. Kromdraai is known for the first discovery of Paranthropus robustus, a more robust line of hominid that existed between 2-1 million years ago in South Africa. Current excavations are being carried out in the open by the Transvaal Museum (Northern Flagship Institution). The University of the Witwatersrand and Harvard University.
Bolt's Farm consists of a series of lime quarries some 2.5-km south-west of Sterkfontein Caves. Fauna discovered from this site Include fossil elephant, pig, antelope, saber-toothed cat and rodents. The fossils indicate a range, of different dates. Certain fossil rodents, for example, dating to about 4.5 million years, make these the oldest deposits in the Cradle of Humankind World Heritage Site. Other species have been dated to between 3.4 -2.9 million years old.
Coopers B is situated about 1.25 km from Sterkfonteln Caves. It became the third South African cave deposit to yield a hominid fossil when a molar tooth was found. Apart from a significant sample of faunal remains the site has yielded part of the face of a Paranthropus (Austra/opithecus) robustus and some isolated teeth.
Gladysvale is located 14km north-east of Sterkfontein in the John Nash Nature Reserve and includes three underground caves and a considerable volume of breccia. Gladysvale preserves one of the most extensive time sequences of any cave in the Cradle of Humankind World Heritage Site. with sediments dating from over 3.0 million years to around 250 years ago. Apart from a few hominid specimens, including two ape-man teeth, the site has yielded the skeleton of a wolf, the skull of a giant hyena and some plant remains.
Hassgat is situated about 5 km from the Hartbeeshoek-Broederstroom road. Early lime mining removed a basal ftowstone from the cave, causing part of the roof to collapse. The collapsed blocks of breccia have yielded a significant faunal sample, although the bone concentration is not particularly high. No hominids have been found thus far. Discoveries in this site include early forest-dwelling monkeys, which indicates that the deposits may be around 1.3 million years old.
Gondolin is located 3.2 km south-west of Broederstroom village. Unlike all the above- mentioned sites, which are located in the Gauteng Province, Gondolin falls within the North West Province. Identified fossils from this site suggest an age of about 1.2- 1.3 million years ago. At present only the Sterkfontein Caves and the Wonder Cave are open to the public.