Cape Town - History is palpable in the Mertenhof rock shelter in the rugged Cederberg. Tread in the dusty soil floor of this small cave overhang overlooking the Biedouw River and just the centimetre or so of sediment that your footprints penetrate will have taken many centuries, perhaps more than a millennium, to accumulate.
So it’s not surprising that it is the subject of intense investigation by archaeologists whose excavation of just 1.5m has already taken them into an era dating back 70 000-to-75 000 years.
“And then it just keeps going down – we haven’t hit the bottom yet,” said Dr Alex Mackay, the Australian scientist who is leading this research.
Going through the remaining 50cm or so of sediment will probably take them “pretty close” to the cave’s bedrock base and back in time to somewhere around 120 000 years ago. But it’s not the only site where his team is working.
Mertenhof is one of a large number of sites (six rock shelters and more than a dozen open-air stone tool “workshops”) that are being investigated as part of a comprehensive research project that is slowly but surely revealing how our early ancestors lived and behaved in the Cederberg region during this formative period in the evolution of Homo sapiens.
Mackay, who has worked extensively on sites in the Western Cape and has a close research association with UCT, has been running the Doring River Palaeo-landscape Project through the University of Wollongong in New South Wales for the past five years, supported by consecutive post-doctoral research grants from the Australian Research Council.
He specialises in stone tools from the Middle Stone Age – the period stretching from about 200 000 to 30 000 years ago when fully modern humans emerged and that is marked by migration pulses out of Africa to other parts of the world.
He and colleagues have been excavating sites like Mertenhof and nearby Klipfonteinrand – both rock shelters on the privately owned Bushmans Kloof Wilderness Reserve – and, for the first time this year, they are simultaneously working another site, about 35km further north at the confluence of the Doring and Biedouw Rivers where deep sediments have accumulated on an undulating alluvial plain.
At this river site, they have identified a highly productive lithic (stone tool) manufacturing “workshop” where an estimated 100 000-plus artefacts, most probably dating from between 8 000 to 120 000 years ago, lie concentrated in just a very small part of this undulating landscape.
One section of sediment is probably more than 400 000 years old and contains stone hand axes, but these are almost certainly not a Homo sapiens product but rather of some earlier hominin species.
More “modern” lithic artefacts both here and at Mertenhof include small bladelets (stone cutting tools, some still sharp enough to draw blood), bifacial and unifacial rock points, and cores – the silcrete, hornfels, quartzite and quartz rocks from which the usable flakes were struck.
The river site excavation was an opportunity to expand the project significantly, Mackay said.
“There’s all this information laid across the landscape, and while it builds up over time, it accumulates in very few places. If you think about it, at a rock shelter excavation you’ve dug one tiny little hole in a continuous space-time matrix, and then you try to interpret human history based on that.
“While these rock shelters are the best places to excavate, each is just one very thin data point, in a sense. So we’re trying to get multiple data points and to exploit all the other evidence that we have.”
This season’s one-month-long fieldwork, just completed at Mertenhof and at the Doring River site, was done by 12 archaeologists from Australia, South Africa, New Zealand and Germany, divided into two teams of six. Mackay led the river site team – two members are his PhD students – while his research and life partner Aara Welz led the rock shelter site.
Mertenhof was targeted partly because of its proximity to water and partly because ground-penetrating radar suggested a fairly good depth of deposit.
And it’s the kind of site that makes archaeologists working elsewhere in Africa green with envy because of the strong existing scholarship on similar rock shelters in southern Africa and the unusually complete sequence through time of this particular site, Mackay said.
“There are probably one or two other sites we know of that are as complete as this, but the sequence right through the last 100 000 years here is quite unusual.”
The upper layers of the six 1m2 excavation plots here produced grass bedding, ostrich eggshell beads, glass beads and bits of ceramic – “Fairly recent stuff, perhaps mixed in with some hunter-gatherer material.”
Directly beneath that, they found material about 16 000 to 22 000 years old. Among the dense concentration of these artefacts – up to 100 are plotted per centimetre of depth – are beautiful little bladelets.
“This little guy, who is as cute as a button, is probably mid-Holocene,” Mackay said, holding one up for inspection by his visitors. (The Holocene is a geological epoch that began at the end of the Pleistocene 11 700 years ago and continues to the present.)
“And we also found pieces of pottery, beads – mostly ostrich shell but also bone and glass – and many nice pieces of ground ochre, the kinds of things that people might have used to make paint with.”
Here the researchers also discovered two burials of three individuals – all children, aged 10 months, 12 months and 3-and-a-half – that could be as “young” as 600 years.
They’re waiting for an age analysis of the bones, which were in a terrible state of preservation and required exceedingly slow and careful work with a lot of bone glue to extract.
The next sequences of the excavation produced artefacts from between 25 000 and 50 000 years ago, and below those some even earlier unifacial points, dating from 50 000 to 60 000 years ago.
“Directly under that, the site kind of goes ballistic and you get evidence of a really intense density of occupation, probably between 60 000 and 70 000 years ago,” said Mackay. “And then below that we move into material that is probably 70 000-to-75 000 and possible as old 120 000.”
The early inhabitants of this region who left these artefacts behind were not only living in caves and overhangs, but also – at times – out in the open.
“When we have these periods of non-occupation of the cave sites, does it mean that the people weren’t there, or were they just not using the caves?” he asked. “And do we use caves equally all through time, or is a cave a particular thing that you use under certain circumstances?”
So the Doring River excavation has provided them with an opportunity “to expand the parts of the fabric” and build up a fuller sense of the people of this area over the last 120 000 years – where they lived, the kind of decisions they made, how they moved across the landscapes, and what the relationships were between the sites they used.
“Because a lot of stone from the river ends up in the cave – so what decisions were made about what to transport?
“We can think about that intuitively in our own lives: when you’re going to spend a lot of time in one place, you take a lot of things, and when you go on short trips after that, you just take a sub-set of that gear. So how are those occupational relationships organised?
“That’s what we’re hoping to get out of this dual site work at the moment.”
It’s known that climatic conditions 18 000 and 22 000 years ago, and also between 60 000 and 70 000 years ago, were probably cooler and wetter than the present – and both of these periods coincide with the evidence of “quite intense” occupation of Mertenhof and similar rock shelters.
“So maybe they were just like English people – they spend all their time ‘indoors’ for those periods of time, they didn’t go out very much,” Mackay joked.
“They’re making use of geologically specific context under certain conditions more than others, but otherwise they’re just us, you know – seeking shelter sometimes, and at others maybe even building their own shelters.”
It’s through the slow and careful aggregation of evidence, rather than finding individual artefacts or investigating single sites, that the archaeologists are able to build up the most coherent and accurate picture of this fascinating occupational history of the Cederberg region and its links to other occupied areas, like the coastal strip at nearby Elands Bay and Verlorenvlei, Mackay said.
“And really that’s the ultimate object of this project – to understand the human occupation of this area over the last 100 000-odd years.”
l Yeld was the guest of Bushmans Kloof Wilderness Reserve.
Sunday Argus