A one day pre-congress field trip across the central Witwatersrand plateau was designed to give the eight participants an introductory overview of the outcrop of the world’s greatest goldfield from which the city of Johannesburg developed.

A number of key exposures were examined including the lowermost Orange Groove quartzite layer of the Witwatersrand succession which directly overlies Archaean granite-greenstone Basement and forms the northern scarp face of the plateau. The magnetic banded iron formation marker layer known as the Contorted Bed within the lower Witwatersrand strata was examined and its importance with respect to the discovery of hidden extensions to the Witwatersrand basin and auriferous reefs was discussed. The lowermost of the gold-bearing conglomerate layers, the Main Reef and Main Reef Leader conglomerates were examined at the Langlaagte discovery site and at the earliest mining site in Johannesburg (Ferreiras stope). The uppermost of the conglomerates forming the southern edge of the Wits plateau were also visited. From this locality on excellent view of the overlying Ventersdorp lava forming the Klipriversberg range south of Johannesburg was obtained.

A number of historical buildings were seen in downtown Johannesburg and we visited the mansion (Northward house) of one of the Randlords, entrepreneurs who pioneered the huge gold mining industry that has played such on important role in the development of South Africa.

The trip was eventfull with one of our group having a bad fall and having to receive stitches. At Langlaagte we encountered a number of Zama Zama’s (illegal miners) who were making use of the old decline to access the underground workings. After some discussion with the head man (the only one with a hard hat) and assuring him that we were only interested in seeing the reef outcrop and not their activities, we were able to get a closer look after being assured that they wouldn’t cause us any trouble. We observed the night shift going underground by sliding down the decline shaft on their behinds with a lamp attached to a woollen cap. I assured our group that this is not exactly the way we do mining on the Witwatersrand today. Sadly three of the Langlaagte Zama Zama’s died as a result of carbon monoxide poisoning underground at Langlaagte one week after our visit and this has again focussed attention on the widespread problem of illegal mining currently taking place in South Africa.

The trip was enjoyed by all, who appreciated the broad impression they gained of the whole Witwatersrand story. Finally my thanks to Alison Blackhurst who assisted me on the trip and to Neil Viljoen for his entertaining introduction to Northward house.

1. First stop for Witwatersrand overview at Northward house of Randlord John Dale Lace and his flamboyant wife Jose. The house was designed by Sir Herbert Baker making use of Orange Grove quartzite building stone.

2. Some of the group at the north face of the Wirtwatersrand plateau scarp face,northward house

3. The Contorted Bed magnetic marker layer within the lower Witwatersrand succession, consting of dark grey bands of magnetite /hematite, red jasper bands and white chert bands . Melle St.

4. Group photograph at the Ferreira stope on the mined -out Main Reef Leader (right) with stringers of oxidised Main Reef in the footwall to the left behind the groups Standard Bank building, 5 Simmonds St., Johannesburg. Photo. Alison Blackhurst

5. Footprint of the re-processed Park Central tailings dump on which paddocks controlling AMD have been established. The Top Star drive-in Cinema was situated on the top of this dump. The story of the early mining history of Johannesburg can be told from the top of the still-intact east side of the tailings dam.

6. Elsburg (Mondeor) conglomerate forming the uppermost succession of the Witwatersrand strata and the southern edge of the Witwatersrand plateau. The Klipriversberg range of lava hills in the background overlies the Witwatersrand with the Victorian mansion (built in 1893) of Johannes Petrus Meyer after whom Johannesburg was named, situated close to the contact.

7. Some of the excursion group at the discovery site of the Witwatersrand gold field on Langlaagte to the west of Johannesburg

8. Some of the excursion group examining the discovery outcrop of the Main Reef and Main Reef Leader conglomerate layers at Langlaagte.

9. Main Reef Leader (dark-brown weathering layer at the top) separated by light quartzite from the underlying Main Reef conglomerate layer, exposed by early mining activity at Langlaagte.