Modern Mining July 2018

COMMENT

Tati Belt’s mysterious wall

W hile attending the recent Botswana Resource Sector Conference (BRSC) in Gabo- rone, I happened to bump into Mike Main. Although he was representing Walkabout Resources, an Australian explorer with graphite, lithium and coal assets in Tanzania, Namibia and Botswa- na respectively, he is a well-known writer with a number of books to his name, mostly dealing with Botswana. Hi s pub l i c a t i ons i nc l ude Af r i can Adventurer’s Guide: Botswana and Kalahari – Life’s Variety in Dune and Delta . The latter was originally published back in the 1980s but I would venture to say that it remains the best single volume guide to the Kalahari you’re ever likely to find. He also recently contributed a chapter (in collaboration with well-known geologist, Mike de Wit) on Botswana’s Tsodilo Hills area to Africa’s Top Geological Sites , a commemorative volume which was published to accompany the 35th International Geological Congress held in Cape Town in 2016. Mike presented me with a conundrum that has stumped me. He has come across a wall – which he describes as a “remarkable structure” – in the Tati Greenstone Belt near Francistown in Botswana. It is somewhat reminiscent of the walls at Great Zimbabwe but could be of more recent origin and, as he says in a follow-up e-mail to me, he would be very interested to know who built it, when they built it and to what purpose. Describing the structure in his e-mail, he says it is “almost hidden in thick bush and is crafted with local stone, clearly by an expert. It

is approximately 7 m tall, 5 m from left to right and tapers from bottom to top. It is about 2,3 m thick at the bottom.” He continues: “It is built on a sloping hill and, immediately on its downhill side, there has been created an excavated space in the hill at least the height of the wall in depth. (In other words, if something were dropped from the top of the wall, say, it would free-fall at least 14 m before hitting the ground). Wider than the wall, this ‘wedge-shaped’ removed section becomes about 10 m wide some distance away from the wall and extends some 80 to 90 m at right angles from the base of the wall.” As Mike points out, the locality was the site of Southern Africa’s first modern gold discov- ery in 1868 which saw the development of a small, primitive mining village – ‘Old Tati Town’ – that barely survived until the 1890s when it was finally abandoned. Although there was some subsequent gold mining about 6 km from the site, for the most part the area has since been primarily cattle range land. Mike adds that there are two piles of quartz- ite rocks within 150 m of the upper side of the wall and speculates on whether there might be a connection – perhaps related to mining activ- ity – between the quartzite and the wall. When I chatted with Mike in Gaborone, he said that he had spoken to mining engineers and geologists in the Francistown area, none of whom could make more than educated guesses as to the origins and purpose of the wall. So, if there are any readers out there who can shed more light on the structure, he would be inter- ested to hear from you. He can be contacted on e-mail mmain@info.bw . Arthur Tassell

It is somewhat reminiscent of the walls at Great Zimbabwe but could be of more recent origin.

Front and side views of the wall in the Tati Greenstone Belt.

July 2018  MODERN MINING  3