Sishen in the semi-arid Northern Cape is one of the world’s largest open-cast iron ore mining operations, extracting more than 30 million tons of ore every year.

But as far back as between about one million and 700 000 years ago, early humans were just as aware of the geological usefulness of this area and, within their limited means, they exploited its banded iron outcroppings extensively to make their stone tools, like hand axes. And the area wasn’t arid then, with archaeological research suggesting it was much wetter and populated by animals like elephants and hippos.

The presence of a “remarkably high” density of artefacts that these hominims (ancestors of modern humans, probably Homo ergaster (meaning “working man”), left behind here has been known to archaeologists since 1980, and some excavations were conducted in 1982.

However, the unique contribution that this site can make to the fascinating story of human evolution development has already been seriously damaged – for example, ironstone outcroppings containing a huge number of artefacts were used as a source of gravel to repair roads.

And now, more development in the expanding mining town of Kathu, the “iron ore capital” of the Northern Cape adjacent to the Sishen mine and industrial area, is further threatening the treasure chest of archaeological deposits of this area.

This is confirmed in the first scientific paper to be published on what is described as “one of the richest early prehistoric archaeological sites in South Africa”.

The paper, by a team of archaeologists from UCT and Canada’s University of Toronto, in collaboration with Kimberley’s McGregor Museum, appears today in the open-access journal PLOS ONE.

It describes their work at a site called Kathu Townlands that is part of the grouping of Earlier Stone Age sites in the area called the Kathu Complex. Another of these sites, some 56km away, is Wonderwerk Cave that has produced the earliest evidence of the use of fire. The team was called in last August as part of a data recovery project to mitigate the archaeological destruction being caused by a mall development.

But the lead author, UCT PhD candidate Steven Walker, is careful to explain that although the site has been designated, but not yet proclaimed, as a grade one heritage site by the SA Heritage Resources Agency (Sahra), the developer has planning permission to build and was “really helpful” during their excavations that produced tens of thousands of artefacts. These included hand axes and other tools characteristic of the Earlier Stone Age that ranged from around 2.5 million to about 400 000 years ago.

It had become apparent during their excavations that the site was probably much bigger than they’d originally thought, Walker said, and he was concerned about its vulnerability to other rapid development happening in the mining town.

“The site is amazing – and it’s threatened. We’ve been working well with developers and Sahra to preserve it, but Kathu is expanding around it and it might get cut off on all sides by development. That would be regrettable as we would then never be able to connect it to the landscape or to establish just how big it is.”

Their paper argues that the Kathu Townlands site represents “a com-plex and massive archaeological context” that requires further research, and concludes:

“Preservation cannot be limited to the presence and absence of surface archaeological material.”