Shakin’ an adze…

An ‘embedded technologist’.  What’s that when he’s at home?  Well, we’ve had one with us and he’s the best in the business.

Karl Lee returned to the UK earlier this week, but during his brief time here he opened our eyes to the importance of working with someone who not only makes stone tools, but also uses them.

Archaeologists label tools based on their shape and assumed function, but Karl has real world knowledge.  He’s skilled in bushcraft and puts replica Stone Age tools through their paces in the wild.  They’re used for cutting, chopping, scraping, and piercing.  He makes shelter, fire, clothing and ‘primitive’ tools for hunting, fishing, and gathering.


Karl Lee with his innovative bone ‘soft’ hammer and hand-axe made using material from Songwe Gorge

He brings a fresh practical perspective on the transition from hand-held to hafted tools which is the focus of the Deep Roots project (see earlier blogs).

We suburban archaeologists don’t live a life remotely like that of any time in the long Stone Age.  Our starting point for understanding early technologies is book-based and, if lucky, some hands-on experience of making stone, bone and wooden tools.  We have a limited anthropological records of  recent hunters and gatherers and their technologies. And there are other tool-making animals, but none makes hafted tools.  And that’s why we need Karl.  He brings more than 20 years of experience to understanding the benefits of hafted over hand-held tools.

We asked Karl to look at one tool form – the ‘core-axe’.  It’s new in the archaeological record 300,000 years ago, roughly at the time of the transition.  It ain’t perty compared to the elegant ‘hand-axes’ of the time, but its lumpy uneven form is intriguing.

Karl with adze1

Chunky core-axe and handle made using local materials

We think it might have been hafted and to test that hypothesis we need to make and use them under controlled conditions.

Karl, working with PhD student Chris Scott, made core-axes using the same stone that was used around Victoria Falls in Early Stone Age.  They had help from John Kanyatta, a Livingstone resident with knowledge of woods used for making the handles traditional tools and resins used as glues.


John showing Karl the kind of bulbous tree root used to make axe handles


The modern axes and adzes have iron working edges, but Karl and Chris adapted the handles to hold stone inserts.  Together they learned to replicate the core-axe, and then set about making binders from local plant fibres.  The bindings, however, didn’t have the strength needed to hold the heavy core-axe.  It shifted in its haft.  They turned instead to a tried and tested binding material – rawhide.

Recipe time. First, get yourself a fresh cow skin (not so easy in a place where cattle are revered), place in a bucket of water, mix with ash from your fire.  Leave overnight. The next day the hair and inner goo (not a technical term) will scrape away easily.

Clean rawhide

Freshly cleaned hide

The rawhide is now ready to slice into thin strips to use as a binding.

Rawhide binding1

Karl made a single strip of rawhide 20 metres (>60 feet) long from this single piece of hide. Amazing stuff

Wrap a strip around your core axe, let dry for a day in the sun and presto you’re ready to whack.

Rawhide knot

As the rawhide strips dry they contract and bind the stone tightly to the handle.  Not a wiggle and ready to use

But before the axe heads were bound, Chris and undergraduate Rachel Stokes took a series of photographs of each piece from several angles to record what the tools looked like before use.

They will do the same after each use.  And there will be many uses on different materials (eg, working wood, digging for roots) at controlled time intervals of up to an hour per tool.* They are building a reference collection and it’s painstaking work.  Handles rarely survive in the archaeological record, and so we need a reliable method of recognising hafting traces on the stone inserts that survive. Interpretation follows from recognition.

Time to test our tools.  The experimental protocol requires using the core-axe in two conditions: hand-held without a haft and with a haft.  We’re not looking forward to chopping wood with the hand-held version, it’s painful based on personal experience, but it must be done.

An important aside: Karl observed that the core-axe is actually an adze. The cutting edge lies horizontal to the axis of the handle whereas an axe blade is vertical. Duh, I hadn’t seen the obvious.

We did ask John to haft two core-axes using his knowledge of traditional iron tools.  We picked them up a few days later and to our surprise he had hafted them vertically like axes.  A challenge to our hypothesis. The stones were slotted into the handles with lots of resin adhesive for good measure.

John and crew

John showing Chris (centre), Rachel (to right of Chris) and Karl (far right) his axe style of hafting a core-adze

Both axes failed quickly, one after just six seconds of gentle wood chopping.

These are core-adzes and that’s the name I’ll be using from now on.

We’ve now used the core-adzes for digging into hard sediment, with and without a handle.  The hafted version is great for digging a vertical section.  Wood working is next.

Martha digging1

Marhta Kayuni, lecturer in archaeology at the University of Zambia using the core-adze to dig

Something odd happened during Karl’s stay.  At Songwe he was busy making tools for our experimental work whilst I was excavating.  Three times he made a particular tool and minutes later I would find the same type in the sands.  Spooky.  Now that we’ve moved to the sands in the Mosi oa Tunya park we’ve been struggling to find artefacts buried in the sands.  They are all over the surfaces but not buried.  The morning Karl left he said we’d find something good when using his replica core-adze.  And so, we did.  Very spooky.

At the base of a geological section and deep into the sands I struck a rock with the core-adze.  Rock on rock makes a distinctive clank.  A fragment of a black sparkling rock lay in the sand.  It wasn’t the adze that broke.  Whatever I’d struck was big and horizontal in the section.


Touch of core-adze damage on the mystery artefact in context

A few minutes of careful brushing and trowelling revealed the first ‘cleaver’ found in context.  It’s a beautiful thing made of ironstone, minus a fresh chip on its working edge. And it’s at the same depth as a spread of other big stone tools found on the surface a few metres away.  The curse of no context may have ended, thank you Karl.


Ironstone cleaver from the sands at the Mosi oa Tunya National Park (minus a piece from its cutting edge – oops!)

And what is a cleaver used for?  We don’t know.  It’ on the ‘to do’ list for our crack experimental team.  Stay tuned.


*This work is supervised by Dr Veerle Rots (TraceoLab, Liège University,  who is a partner on the Deep Roots project

3 thoughts on “Shakin’ an adze…

  1. Now that’s really interesting (not, of course, that it isn’t all interesting), and what an unusual person Karl seems to be. Where does he come from?


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About Larry Barham

My name is Larry (Lawrence if I’m feeling formal) Barham and I'm a Professor of African Archaeology at the University of Liverpool, England, teaching evolutionary anthropology at undergraduate and postgraduate level.