Not many robots have been to Wairau Bar – in fact, to my knowledge, only one. It’s a vital member of the archaeological team, although it can’t dig or think or speak. It has no arms or face or fancy robotic excavating tools, but I was secretly delighted to find out it does shoot a laser out of it’s one all-seeing eye. It’s called a Total Station and it’s the first of an array of highly sophisticated archaeological surveying techniques being used by the University of Otago scientists.
Things have come a long way since study began on this site. The first (European) person to discover a grave here was a 13-year old school boy who used his father’s potato fork and a piece of number 8 wire to excavate in 1939. When professional scientists began to investigate Wairau Bar in the 1940’s and 50’s, they were limited to the technology of the time – mainly trowels, string and tape measures (We’ll go into more detail about the early excavations in the next post). All these basic tools are still being used right now on the 2009 Wairau investigations, and they work perfectly well, but the trick is working out exactly where to dig in the first place – something that is extra critical in this case.
As I mentioned before, the primary purpose of our time here is to find a suitable location for the repatriation of the human remains taken in previous times, as well as employ modern archaeological methods to study other aspects of the 700-year old village that once existed at Wairau Bar. Because it is a huge site – at least 8 hectares, maybe up to 15 – very little is known about what else might be buried beneath the flat wind-blown expanses of the northern end of the Bar.
The idea is to return those ancestors to as close as possible to their original burial place, but at the same time avoid disturbing any other graves that may still lie undiscovered. It’s strange to think that this archaeological expedition actually really doesn’t want to find anything too spectacular! (at least in terms of human remains).
Luckily there are some really clever and hi-tech methods available to narrow the odds of excavating in the wrong place – and that’s where the robot and laser come into it. To the naked eye, the Bar looks pretty barren and featureless – there’s nothing really obvious that indicates where structures or other features of the settlement may have been. But there are subtle clues in the topography of the land. To detect these clues, the archaeologists are creating an incredible detailed 3-D map of the area, using a device called Total Station. There’s nothing particularly new about surveying the surface of a piece of land – the main tool to do it – the theodolite – has been around for a century or more. You’ve probably seen a surveyor using one – they look like a telescope on top of a tripod, aimed at some other joker down the road holding a stick. But Total Station is an automatic, robotic theodolite that can collect an incredible amount of very detailed data in a short amount of time. This is Associate Prof Richard Walter setting it up :
It has to be put in exactly the right spot to begin with – this entire survey is based around one tiny point on the ground called Datum 1 which has been exactly pin-pointed and located in 3 dimensions within a fraction of a millimetre. Every other measurement that is taken on the 8-hectare site is referenced to this one spot. Once Total Station is in place directly on top of Datum 1, a few hundred metres away Bruce starts up the other vital part of the system – a Quad bike.
That thing on the end of the pole is a prism, which Total Station’s laser will lock on to and follow.
Bruce starts driving up and down from one side of the survey area to another, and as I watch, Total Station starts to track him – well the prism on the end of the stick, at least. It’s impressive to watch – the robotic instrument starts following him backwards and forwards, and as the Quad bike passes over dips and humps the changes in height of the prism are recorded with incredible accuracy.
It takes about a day to cover the area the archaeologists are interested in, but at the end of it they have 20,000 individual measurements of the exact shape of the land in the potential excavation area.
Richard Walter tells me to get that many data points it would take an old-school surveyor and theodolite about 4 years!
When it’s plotted on a 3-d map, the shape of the land is revealed :
This is a version with a few labels added so you can see what this kind of technology can tell us (I made these labels by the way – a real scientist would never be so messy!!) :
Pretty cool, huh? The map generated by Total Station reveals all kinds of interesting things hard to see with the naked eye. The row of pits along the side of the road (which obviously wasn’t there 700 years ago) are a real mystery. There are maybe 70 of them on Wairau Bar, about 15 feet across and 4 or 5 deep. They could be some kind of natural erosion feature, but archaeological remains have been found in some of them, suggesting even if they are naturally formed they were definitely used for some purpose by the ancient people of Wairau Bar. Maybe they built houses in them to keep out of the wind that seems to howl across the bar constantly?
The map also shows some other interesting pits and depressions that hopefully we may be able to study more closely. Whatever happens, this area is now one of the most accurately measured pieces of ground on Earth…
That’s it for now – before I head off to sleep (nobody told me running a blog means you have to stay up all night!) I’d just like to thank everyone who has taken the time to check out the blog and send in comments. It’s great to get your feedback – please keep it coming. If there’s something specific you’d like to know, fire your questions in and I’ll sort out one of our team to answer them.