67-406: The Vredefort impact structure is the largest verified impact structure on Earth . The crater, which has since been eroded away, has been estimated at 170–300 kilometres (110–190 mi) across when it was formed. The remaining structure, comprising the deformed underlying bedrock, is located in present-day Free State province of South Africa . It is named after the town of Vredefort , which
134-834: A continental divide , with the run-off to the north draining into the Indian Ocean via the Crocodile and Limpopo rivers, while the run-off to the south drains via the Vaal into the Orange River and ultimately into the Atlantic Ocean . Because of the extraordinary quantities of gold that have been extracted from the Witwatersrand rocks, the South African currency was named the rand in 1961 upon
201-662: A 56 km long east–west ridge over which several rivers running to the north form waterfalls, giving rise to the name Witwatersrand, which in Afrikaans means "Ridge of White Waters". There was no free oxygen in Earth's atmosphere until about 2 billion years ago, before the appearance and sufficient development of photosynthesizing cyanobacteria . The oxygen produced by these microorganisms rapidly reacted with, amongst others, Fe ions dissolved in water, precipitating insoluble red iron oxide ( hematite ). For various reasons,
268-556: A broadcasting licence was granted by ICASA to a community radio station to broadcast for the Afrikaans- and English-speaking members of the communities within the impact structure. The Afrikaans name Koepel Stereo (Dome Stereo) refers to the dome and announces its broadcast as KSFM. The station broadcasts on 94.9 MHz FM. List of impact craters on Earth#10 Ma or more Download coordinates as: This list of impact structures (including impact craters) on Earth contains
335-490: A diameter of less than one km (0.62 mi): From between ten thousand years and one million years ago, and with a diameter of one km (0.62 mi) or more. The largest in the last one million years is the 14-kilometre (8.7 mi) Zhamanshin crater in Kazakhstan and has been described as being capable of producing a nuclear-like winter . The source of the enormous Australasian strewnfield (c. 780 ka )
402-471: A shallow sea, conveniently named the "Witwatersrand Sea". The resulting 2500–4500 m thick layer of sediments is termed the "West Rand Group" of Witwatersrand rocks. The second phase, which lasted for 200 million years, followed on from the first phase, with on-land deposits, resulting from the retreat of the Witwatersrand Sea, leaving a wide almost flat coastal plain over which rivers from
469-620: Is a currently undiscovered crater probably located in Southeast Asia. From between 1 and 10 million years ago. The large but apparently craterless Eltanin impact (2.5 Ma) into the Pacific Ocean has been suggested as contributing to the glaciations and cooling during the Pliocene. Most recorded impact craters are over 10 million years old, or have widely uncertain ages. The Chicxulub impact has been widely been considered
536-451: Is also one of the largest meteor impacts to have left its imprint on present-day Earth geology. A meteor 10–15 km across created a 300 km diameter crater, distorting all the rock strata within that circle. Johannesburg is just within the outer edge of this impact crater. In the immediate vicinity of the impact all the subterranean strata were uplifted and upturned, so that Witwatersrand rocks are exposed in an arc 25 km away from
603-516: Is clear that for the next 200 million years the flood plain was repeatedly inundated, sometimes eroded, and sediments re-deposited. The result was a 2500 m thick layer of rock that is termed the "Central Rand Group", which together with the "West Rand Group", forms the "Witwatersrand Supergroup". It is the younger Central Rand Group that contains most of the gold bearing conglomerates, locally referred to as banket , that are today of great economic importance. The "Central Rand Group" of deposits
670-504: Is estimated to have been one of the largest ever to strike Earth since the Hadean Eon some four billion years ago, originally thought to have been approximately 10–15 km (6.2–9.3 mi) in diameter. As of 2022, the bolide was estimated at between 20 and 25 kilometres (12 and 16 mi) in diameter and to have impacted with a vertical velocity of 15–25 kilometres per second (34,000–56,000 mph). The original impact structure
737-422: Is estimated to have had a diameter of at least 170 km (110 mi), with the impact affecting the structure of the surrounding host rock in a circular region around 300 km (190 mi) in diameter. Other estimates have placed the original crater diameter closer to 300 km (190 mi). The landscape has since been eroded to a depth of around 7–11 km (4.3–6.8 mi) since formation, obliterating
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#1732765368529804-621: Is near its centre. The structure's central uplift is known as the Vredefort Dome . The impact structure was formed during the Paleoproterozoic Era , 2.023 billion (± 4 million) years ago. It is the second-oldest known impact structure on Earth, after Yarrabubba . In 2005, the Vredefort Dome was added to the list of UNESCO World Heritage Sites for its geologic interest. The asteroid that hit Vredefort
871-405: Is sometimes carried out at depths of 4 kilometres (2.5 mi) below the surface. The Witwatersrand Basin is a largely underground geological formation which surfaces in the Witwatersrand. It holds the world's largest known gold reserves and has produced over 40 000 tonnes (1.3 × 10 ozt), which represents about 22% of all the gold accounted for above the surface. The basin straddles
938-498: Is suggested this situation is an artifact, highlighting the importance of intensifying research in less studied areas like Antarctica , South America and elsewhere. Links in the column "Continent" will give a list of craters for that continent. Witwatersrand The Witwatersrand ( UK : / w ɪ t ˈ w ɔː t ər z r æ n d , - r ɑː n d / , US also / ˈ w ɪ t w ɔː t ər z -/ ; Afrikaans pronunciation: [ˌvətˌvɑːtəɾsˈɾant] ; locally
1005-641: Is the 4.5 km (2.8 mi) Rio Cuarto crater in Argentina . However, there is some uncertainty regarding its origins and age, with some sources giving it as < 10 ka while the EID gives a broader < 100 ka. The Kaali impacts ( c. 1500 BC ) during the Nordic Bronze Age may have influenced Estonian and Finnish mythology , the Campo del Cielo ( c. 2500 BC ) could be in
1072-522: The Earth Impact Database (EID) contains 190 confirmed impact structures. The table below is arranged by the continent's percentage of the Earth's land area, and where Asian and Russian structures are grouped together per EID convention. The global distribution of known impact structures apparently shows a surprising asymmetry, with the small but well-funded European continent having a large percentage of confirmed impact structures. It
1139-802: The Orosirian Period of the Paleoproterozoic Era. It is the second oldest universally accepted impact structure on Earth. In comparison, it is about 10% older than the Sudbury Basin impact (at 1.849 billion years) and the Yarrabubba impact structure is older than the Vredefort impact structure by about 0.2 billion years. Other purported older impact structures have either poorly constrained ages ( Dhala impact structure , India) or highly contentious impact evidence in case of
1206-592: The Witwatersrand Basin which was laid down over a period of 250 million years between 950 and 700 million years before the Vredefort impact. The overlying Ventersdorp lavas and the Transvaal Supergroup which were laid down between 700 and 80 million years before the meteorite strike, were similarly distorted by the formation of the 300-kilometre-wide (190 mi) impact structure. The rocks form partial concentric rings around
1273-508: The bed of the nearby Vaal River . This impact structure is one of the few multiple-ringed impact structures on Earth, although they are more common elsewhere in the Solar System. Perhaps the best-known example is Valhalla crater on Jupiter 's moon Callisto . Earth's Moon has some as well. Geological processes, such as erosion and plate tectonics , have destroyed most multiple-ring impact structures on Earth. The impact distorted
1340-645: The crust is derived from gold in the mantle which resulted from a meteorite bombardment some 3900 million years ago (i.e., at approximately the time that the Kaapvaal Craton formed). The gold bearing meteorite events occurred millions of years after the segregation of the Earth's core. The gold in the Witwatersrand Basin area was deposited in Archean river deltas having been washed down from surrounding gold-rich greenstone belts to
1407-494: The "West Rand Group" of sediments caused the Witwatersrand sea to retreat. The area of the craton on top of which Johannesburg is now situated, became a vast riverine plain, which extended along the entire northern and western shoreline of the shrunken sea, in an arc extending from Evander in the east, through Johannesburg, Carletonville and then southwards to Klerksdorp and Welkom in the south-west. The rivers formed braided deltas with many interlacing, slow flowing channels where all
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#17327653685291474-484: The "Witwatersrand Sea" to the south, where the earlier sediments that form the older rocks of the Witwatersrand Supergroup had been deposited. Some of these gold bearing fan deltas are now at depths of 4 km (2.5 mi) below the surface. Although many of the older mines, around Johannesburg, are now nearly exhausted, the Witwatersrand Basin still produces most of South Africa's gold and much of
1541-413: The "Witwatersrand Supergroup", consists of very hard erosion resistant quartzites , banded ironstones and some marine lava deposits, interspersed with softer, more easily eroded tillites , mudstones and conglomerates . The oldest rocks (laid down 2.97 billion years ago) form the northern scarp of the Witwatersrand plateau; the youngest (laid down 2.71 billion years ago) are those that form
1608-497: The Archean Eon, but island arcs did form. It was the coalescence of several of these island arcs that led to the formation of the Kaapvaal Craton , one of the first microcontinents to form on Earth about 3.9 billion years ago. Its size and position relative to Southern Africa today are indicated in the diagram on the left. About 3 billion years ago local cooling of the underlying asthenosphere caused subsidence of
1675-666: The Rand or, less commonly, the Reef ) is a 56-kilometre-long (35 mi), north-facing scarp in South Africa . It consists of a hard, erosion-resistant quartzite metamorphic rock, over which several north-flowing rivers form waterfalls, which account for the name Witwatersrand, meaning 'white water ridge' in Afrikaans . This east-west-running scarp can be traced with only one short gap, from Bedfordview (about 10 km [6.2 mi] west of O.R. Tambo International Airport ) in
1742-510: The Vaal River and the impact structure. The granting of prospecting rights around the edges of the impact structure has led environmental interests to express fear of destructive mining. The Vredefort Dome in the centre of the impact structure is home to four towns: Parys , Vredefort, Koppies and Venterskroon . Parys is the largest and a tourist hub; both Vredefort and Koppies mainly depend on an agricultural economy. On 19 December 2011,
1809-667: The Ventersdorp lavas at a distance of about 35 km (22 mi) from the centre, and the Transvaal Supergroup, consisting of a narrow band of the Ghaap Dolomite rocks and the Pretoria Subgroup of rocks, which together form a 25-to-30-kilometre-wide (16 to 19 mi) band beyond that. From about halfway through the Pretoria Subgroup of rocks around the impact structure's centre, the order of
1876-498: The Vredefort Dome, virtually all the other outcrops occur in an arc approximately 80–120 km from the centre of the impact crater, to the west, north-west, north and north-east. Thus, it is possible that if it had not been for the Vredefort asteroid strike 2 billion years ago, we would either have never discovered the rich gold deposits beneath the Southern African surface, or they would have been eroded away during
1943-463: The Witwatersrand, these were alluvial concentrates in contemporary rivers, or in quartz veins, in the form that gold had always been found elsewhere on earth. When George Harrison, probably accompanied by George Walker, found gold on the farm Langlaagte, 5 km (3 mi) west of what would become the city of Johannesburg, in an outcrop of conglomerate rocks, in February 1886, they assumed that this
2010-582: The basin is deeply buried under younger rocks, but outcrops occur in Gauteng , the Free State , as well as in some of the surrounding Provinces. The outcrop in Gauteng forms the Witwatersrand ridge, from which the basin and its rocks derive their name. It was on the southern portion of this ridge that gold was first discovered on the farm Langlaagte in 1886, 5 km west of Johannesburg . Since this gold
2077-463: The circa 3.023 billion year old Maniitsoq structure , West Greenland and the circa 2.4 billion year old Suavjärvi structure , Russia. Their classification as impact structures remain controversial and unsettled. The dome in the centre of the impact structure was originally thought to have been formed by a volcanic explosion, but in the mid-1990s, evidence revealed it was the site of a huge bolide impact, as telltale shatter cones were discovered in
Vredefort impact structure - Misplaced Pages Continue
2144-522: The declaration of the republic. Witwatersrand and the Rand are names for the conurbation that developed along the range , although the terms are falling into disuse and Witwatersrand was the "W" in PWV (Pretoria-Witwatersrand-Vereeniging), the initial name of Gauteng province. In this context, it has lent its name to institutions including the University of the Witwatersrand (Wits University) and
2211-501: The defunct Rand Afrikaans University (RAU, now part of the University of Johannesburg ), and to towns and regions such as the East Rand , West Rand and Randburg . The Witwatersrand plateau consists of a 5 000 -to- 7 000 -metre-thick (3.1–4.3 mi) layer of mainly sedimentary rocks laid down over a period of about 260 million years, starting approximately 2.97 billion years ago. The entire series of rocks, known as
2278-485: The east, through Johannesburg and Roodepoort , to Krugersdorp in the west (see the diagram at left below). The scarp forms the northern edge of a 7-to-10-kilometre-wide (4–6 mi) plateau (or ridge) which rises about 200 m (660 ft) above the surrounding plains of the Highveld . A number of picturesque Johannesburg suburbs, including Observatory , Linksfield Ridge and Upper Houghton are located along
2345-464: The first glaciation episodes on earth. Within 60 million years, up to 4500 m of sediment had accumulated on the granite base, to become the "West Rand Group" of rocks that contribute over 60% of the total thickness of the Witwatersrand Supergroup. Uplifting of the north of the Kaapvaal Craton, in addition to orogenesis (mountain formation), towards the end of the deposition of
2412-475: The geology of the Witwatersrand Basin and its exposure in the Johannesburg region, was a massive meteor impact 110 km to the south-west of Johannesburg 2.02 billion years ago. The impact was close to the present village of Vredefort, which has given its name to the geological remnant of this immense event: the Vredefort Dome. Not only are the remains of this impact among the oldest on Earth, but it
2479-675: The gold that is accounted for today. Not all the conglomerates contain gold, and of those that do (known as "reefs" by the miners), the gold is not uniformly distributed throughout the layer, but tends to occur in streaks, where the pebbles that make up the conglomerate are larger than elsewhere. Here the gold is associated with other minerals, especially iron pyrite and uraninite , as well as carbon rich materials such as kerogen , or bitumen , which occurs in small balls less than 1 mm (0.04 in) in size, called "flyspeck carbon", or as continuous layers about 10–20 mm (0.4–0.8 in) thick. The gold-bearing conglomerates occur chiefly in
2546-445: The heavy materials brought down from the mountains were deposited: large pebbles, and heavy minerals, such as gold , iron pyrite , and uraninite . The gold was in its free elemental form. Cyanobacteria grew in relative abundance in these mineral rich waters. The kerogen , or bitumen , that is found in association with the gold deposits almost certainly represents what remains of these Archean photosynthesizing micro-organisms. It
2613-677: The historic Witwatersrand Gold Rush . Harrison is believed to have sold his claim for less than £10 before leaving the area, and he was never heard from again. Harrison's original Zoekers' (in English: seekers', or prospectors') Claim No 19 was declared a national monument in 1944, and named Harrison's Park. The park is on the busy Main Reef Road, immediately west of Nasrec Road. In 1887 Cecil John Rhodes registered "The Gold Fields of South Africa" in London, South Africa's first mining house, with
2680-416: The impact centre. There are no gold deposits in these outcrops. The meteor impact, however, lowered the Witwatersrand basin inside the crater. This protected it from erosion later on; but, possibly more importantly, bringing it to the surface close to the crater rim, near Johannesburg. In fact, apart from the Witwatersrand outcrops (i.e. where these rocks are exposed at the surface) in the immediate vicinity of
2747-539: The impact structure's centre today, with the oldest, the Witwatersrand rocks, forming a semicircle 25 km (16 mi) from the centre. Since the Witwatersrand rocks consist of several layers of very hard, erosion-resistant sediments (e.g. quartzites and banded ironstones ), they form the prominent arc of hills that can be seen to the northwest of the impact structure's centre in the satellite picture above. The Witwatersrand rocks are followed, in succession, by
Vredefort impact structure - Misplaced Pages Continue
2814-569: The legends of some Native Argentine tribes, while Henbury ( c. 2700 BC ) has figured in Australian Aboriginal oral traditions. For the Rio Cuarto craters, 2002 research suggests they may actually be aeolian structures. The EID gives a size of about 50 m (160 ft) for Campo del Cielo, but other sources quote 100 m (330 ft). From between 10 thousand years and one million years ago, and with
2881-426: The majority of the 194+ confirmed impact structure given in the Earth Impact Database as of 2024. Alphabetical lists for different continents can be found under Impact structures by continent below. These features were caused by the collision of meteors (consisting of large fragments of asteroids ) or comets (consisting of ice, dust particles and rocky fragments) with the Earth. For eroded or buried craters,
2948-698: The most likely cause for the Cretaceous–Paleogene mass extinction , with some scholars linking other impacts like the Popigai impact in Russia and the Chesapeake Bay impact to later extinction events, though the causal relationship has been questioned. Some impact events are only known from events like layers of spherules or tektites generated by the impact recorded in contemporary rocks, and their impact structures may no longer exist. As of 2022 ,
3015-401: The north and west. Rhenium - osmium isotope studies indicate that the gold in those mineral deposits came from unusual 3 billion year old mantle -derived intrusions known as komatiite , present in the greenstone belts. Apart from the obvious hollowing out of the rocks below southern Johannesburg, causing unpredictable sinkholes, surface instabilities and earth tremors, the bringing to
3082-415: The north formed wide braided river deltas , into some of which rich deposits of gold were deposited. The resulting 2500 m thick layer of rock is termed the "Central Rand Group". The "West Rand Group" and "Central Rand Group" of rocks together form the "Witwatersrand Supergroup", the full horizontal extent of which is termed the Witwatersrand Basin. There were no continents during the early stages of
3149-463: The north-east to Theunissen in the south-west, and 150 km (93 mi) wide stretching from Steynsrus in the south-east to Coligny in the north-west, with a small subsidiary basin at Kinross . Gold occurs only along the northern and western margins of this basin, but not in a continuous band. The gold-bearing rocks are limited to six sites where Archean rivers from the north and west formed fan deltas, with many braided channels, before flowing into
3216-509: The old provinces of Transvaal and the Orange Free State , and consists of a 5000–7000 m thick layer of Archean , mainly sedimentary rocks laid down over a period of about 260 million years, starting about 3000 million years ago. The entire series of rocks, known as the "Witwatersrand Supergroup" consists of quartzites , banded ironstones , mudstones , tillites , conglomerates and some marine lava deposits. Most of
3283-406: The oldest microcontinents which formed on Earth 3.9 billion years ago. This central peak uplift, or dome, is typical of a complex impact structure, where the liquefied rocks splashed up in the wake of the meteor as it penetrated the surface. The Vredefort Dome World Heritage Site is currently subject to property development, and local owners have expressed concern regarding sewage dumping into
3350-422: The original crater. The remaining structure, the "Vredefort Dome", consists of a partial ring of hills 70 km (43 mi) in diameter, and is the remains of the central uplift created by the rebound of rock below the impact site after the collision. Estimates have placed the structure’s age to be 2.023 billion years (± 4 million years) or 2.019/2.020 billion years (± 2-3 million years) old, which places it in
3417-746: The phenomenon is called, has become a major ecological problem, because it dissolves many of the heavy elements, such as the uranium , cadmium , lead , zinc , copper , arsenic and mercury found in the mine dumps, facilitating their passage into surface water and ground water. The tailings ponds contain an average of 100 mg/kg of U 3 O 8 , and uranium levels are measureable in human hair. Sulfuric acid also erodes concrete and cement structures, resulting in structural damage to buildings and bridges. Although gold had been discovered in various locations in South Africa, such as Barberton and Pilgrim's Rest , as well as at several sites near
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#17327653685293484-482: The rocks is reversed. Moving outwards towards where the crater rim used to be, the Ghaap Dolomite group resurfaces at 60 km (37 mi) from the centre, followed by an arc of Ventersdorp lavas, beyond which, at between 80 and 120 km (50 and 75 mi) from the centre, the Witwatersrand rocks re-emerge to form an interrupted arc of outcrops today. The Johannesburg group is the most famous one because it
3551-505: The scarp, overlooking the rest of northern Johannesburg with views up to the Magaliesburg (although locals refer to segments of the scarp using area-specific names, such as Linksfield Ridge , Parktown Ridge or Observatory Ridge ). The entire plateau-like structure is also often called the Witwatersrand. The plateau's elevation above sea-level is between 1,700 and 1,800 metres (5,600–5,900 ft). The Witwatersrand plateau forms
3618-535: The sedimentation of the fine grain mud was affected by cyclic episodes with more or less precipitation of iron oxides. The result was alternating red and beige layers of mud which, when consolidated, became banded ironstones . As the sea deepened, finer grained and muddy sediments accumulated. Changing geographical conditions resulted in the accumulation of a wide variety of sediments, ranging from mud, to sand, to gravel, and banded ironstones . Tillite deposits, dating from 2.95 billion years ago, are indicative of
3685-647: The south eastern portion of this microcontinent below sea level. The floor of this newly formed "Witwatersrand sea" consisted of smoothly eroded granites . Sandy sediments brought in by rivers from the north started being deposited on the granite about 2.97 billion years ago. This sandy layer eventually became compressed to form the Orange Grove Quartzite, the lowermost layer of the Witwatersrand Supergroup. This quartzite layer can be seen lying on its granite base in Johannesburg , where it forms
3752-468: The southern edge of the plateau. Gold is found in the conglomerate strata of the younger members of the Supergroup, locally referred to as banket . The abundance of this gold is without a natural equal anywhere else in the world. Over 40,000 tonnes (44,000 short tons) have been mined from these rocks since this precious metal was first discovered here in 1886. This accounts for approximately 22% of all
3819-409: The stated diameter typically refers to the best available estimate of the original rim diameter, and may not correspond to present surface features. Time units are either in ka (thousands) or Ma (millions) of years. Less than ten thousand years old, and with a diameter of 100 m (330 ft) or more. The EID lists fewer than ten such craters, and the largest in the last 100,000 years (100 ka)
3886-421: The surface of rocks that had been laid down in oxygen-free conditions had unforeseen effects. Iron pyrite (FeS 2 ), which is relatively plentiful in the gold ores of the Witwatersrand, oxidises to insoluble ferric oxide (Fe 2 O 3 ) and sulfuric acid (H 2 SO 4 ). Thus, when mine waste comes into contact with oxygenated rainwater, sulfuric acid is released into the ground water. Acid mine drainage , as
3953-441: The total world output. Silver , uranium , and iridium are recovered as gold-refining by-products. The Witwatersrand basin was created during the Archean Eon, and is therefore amongst the oldest geological structures on Earth. It was laid down in two stages, over the course of 260 million years starting just short of 3 billion years ago. The first phase, lasting 60 million years, consisted of sedimentary deposits in
4020-510: The uninterrupted removal of a several kilometres thick layer of deposits from the surface of the Southern African Plateau in the relatively recent geological past: i.e. the past 150 million years, but especially during the last 20 million years. The vast majority of the Earth's gold and other heavy metals are locked up in the earth's core . Evidence from tungsten isotope studies indicates that most gold in
4087-426: The upper, younger layers of the Witwatersrand Supergroup of rocks, on the southern side of the Witwatersrand plateau. The Witwatersrand Supergroup strata which reach the surface in Johannesburg dip downwards to the south at an angle of about 30°. From there on they are almost everywhere, with very few exceptions (see below), covered by younger rocks. Gold mining in these buried portions of the Witwatersrand Supergroup
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#17327653685294154-534: Was alluvial gold in an old riverbed, that had been tilted as a result of earth movements. However, when it was found that, traced downdip, the conglomerate was not merely developed for the narrow width of a river, but continued in depth, there came the realisation that this conglomeratic zone was part of a sedimentary succession. Harrison had stumbled on the Main Reef conglomerate (part of the "Johannesburg Subgroup" of rocks — see illustration above). The conglomerate
4221-472: Was brought to an abrupt end by massive outpourings of lava, which form the Ventersdorp lavas which erupted 2.715 billion years ago. The cause of these lava outpourings is a matter of speculation. It might be related to the collision of the Kaapvaal Craton with the Zimbabwe Craton , eventually to become knitted together to form a single continental unit. A final event that had a major impact on
4288-419: Was embedded in a conglomerate, it was first assumed that this was alluvial gold in an old riverbed, that had been tilted as a result of earth movements. However, when it was found that, traced downdip , the conglomerate was not merely developed for the narrow width of a river, but continued in depth, there came the realisation that this conglomeratic zone was part of a sedimentary succession . The conglomerate
4355-527: Was here that gold was discovered in 1886. It is thus possible that if it had not been for the Vredefort impact this gold would never have been discovered. The 40-kilometre-diameter (25 mi) centre of the Vredefort impact structure consists of a granite dome (where it is not covered by much younger rocks belonging to the Karoo Supergroup ) which is an exposed part of the Kaapvaal craton , one of
4422-548: Was quickly traced east and westward for a total continuous distance of 50 km (31 mi) to define what became known as the "Central Rand Gold Field". Harrison declared his claim with the then-government of the Zuid Afrikaanse Republiek (ZAR), and in September 1886 President Paul Kruger issued a proclamation declaring nine farms public mining diggings, starting on 20 September 1886. This heralded
4489-497: Was quickly traced east and westward for a total continuous distance of 50 km (31 mi) to define what became known as the "Central Rand Gold Field". It has since been established that the rocks that make up the Witwatersrand Ridge dip downwards and southwards to form the largely underground "Witwatersrand Basin" which covers an elliptical area with a 300 km (190 mi) long major axis from Evander in
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