Prospecting for Meaning: Archaeology, Symbolism, and Mineral Exploration in Zambia

Andrew Zipkin
Andrew at Victoria Falls.
By Andrew Zipkin
September 04, 2013

Two weeks ago I returned Stateside after a 9 week field season in Zambia, Kenya, and Ethiopia. Working in Zambia this summer was the culmination of an idea I had been kicking around since I was an undergraduate arguing with Prof. Tom Volman and my classmates at Cornell University about whether or not human ancestors possessed the capability for material symbolism, among other recognizable modern behaviors. That topic is too vast for a blog entry but for those interested in the decade and half of academic debate on the subject, start with McBrearty and Brooks’ “The Revolution that Wasn’t” (2000) and about an hour and a half of spare time.

The short version is that until fairly recently most archaeologists believed that humans only began acting in a way comparable to modern people about 50,000 years ago, when symbolism, art, and language underwent an abrupt flowering. This interpretation had a number of problems, including an initial Eurocentric bias which downplayed the evidence from Africa, but for the most part it fit the available data. In the last 15 years or so though, Stone Age archaeology in Africa and the Middle East has produced more and more evidence suggesting that people were engaging in complex behaviors no different from today far earlier than 50,000 years ago. Discovery of various iron-rich mineral pigments (let’s just call it all ochre for the sake of simplicity) modified by humans into powders and paints or used as a substrate for engraving has drawn a great deal of attention in the last ten years, even though material symbolism is only one member of large and variably defined suite of behaviors that constitute “modernity”. Most of the ochre evidence comes from South Africa with a few important sites in East Africa and the Middle East; but what about that giant piece of the continent in the middle? See? Zambia does come into this eventually; I didn’t forget the title of the article after all.

Image 1 – Specularite boulder with weathering, Sanje Hill

So the whole point of my working in Zambia was to follow up on some excellent research done there in the late 1990s by Prof. Larry Barham of the University of Liverpool at a site called Twin Rivers Hill. For his part, Larry was updating with modern excavation techniques and dating the pioneering excavation J. Desmond Clark conducted at Twin Rivers during the 1950s. Twin Rivers is a collapsed cave site on the side of a small hill which rises abruptly from the Kafue Flats; what brought me there was the evidence of ochre collection published by Barham during the late 1990s and early 2000s. The dating of Twin Rivers is somewhat controversial depending on whom you are asking but general idea is that the site was occupied during the Middle Pleistocene by human ancestors, presumably of the species Homo heidelbergensis (or Homo rhodesiensis if you are so inclined taxonomically). Barham’s work indicated that not only was a great deal of ochre present in the archaeological deposits at Twin Rivers but that there was good evidence of a collection bias favoring high iron content ochres with striking visual properties. Specular hematite, or specularite, is effectively high grade iron ore that is composed mostly of Fe by mass. Chemically it is the same as regular red hematite but a quirk of its crystal structure makes it look like silver-gray glitter unless it is ground up into fine powder.

My task this summer was to figure out where the specularite at Twin Rivers came from and whether it was the only option for ochre available on the landscape or if the people at Twin Rivers were going out of their way to acquire it in preference to other mineral pigments. Although the ochre at Twin Rivers is not undeniable evidence of symbolism in its own right, if I can confirm that ochre collection there was driven by a preference for pigments with specific visual properties this will go a long way towards proving the case for material symbolism during the Middle Pleistocene. In practice this amounted to me camping south of Lusaka for about 4 weeks and talking my way into private farmland, industrial quarry operations, and artisanal copper mines so I could prospect for ochre. The mining sector accounted for about 11% of the Zambian GDP in 2010 and it is expected to continue to grow, despite a recent fall in copper prices. Needless to say, a foreigner walking around Zambia collecting rock samples can attract some attention. At Eureka Camping Park along the Kafue Road the bar was usually occupied by a rotating cast of overland tour groups but most nights at least a couple of foreigners in the area on mining business could be found discussing their prospects over a few Mosis.

Image 2 – Kacheta Pit

The Kafue Flats are mostly an agricultural area but the mining industry is expanding beyond its traditional emphasis on the Copperbelt region. Small, artisanal, and frequently unlicensed mining operations pop up wherever a farmer uncovers a vein of copper or manganese ore; one day while collecting samples from a massive specularite deposit at Sanje Hill (Image 1) my local guides told me about several nearby mines that were producing copper and iron ore on a small scale (Image 2). About a half hour’s walk brought us to a landscape pockmarked with artisanal mines excavated every way imaginable, ranging from pickaxes, to rented backhoes, to dynamite purchased from who knows where. While the cost-benefit analysis of environmental and cultural heritage cons versus economic pros is definitely open to interpretation, one undeniable perk of working in area like this was not having to open any new excavations as part of my geological research. Existing open pit mines and geological trenches provided ample opportunity for observing stratigraphic sections and collecting ochre samples.

Now that the field season is done and my samples are all exported the real work begins. Over the next few months I will use mass spectrometry to determine the trace element “fingerprint” of my ochre source samples and try to match them up with the ochre artifacts excavated by Barham and Clark from Twin Rivers. With any luck, it will be possible to identify the specific sources on the landscape from which ochre was collected and transported back to Twin Rivers. In combination with measurements of the color of each ochre artifact and source sample, this should allow me to interpret whether or not the Middle Stone Age inhabitants of Twin Rivers ignored nearby sources of red and yellow pigment and went the extra distance to acquire specularite. It’s an admittedly roundabout way of studying symbolism but it has the advantage of relying on largely objective, quantitative methods and I’m optimistic that it will be fruitful. Next time I’ll let you know if those fruit prove to be sparkly, iron-rich, and non-local.