Modern Technology and the Archaeological Record

June 22, 2018

Knysna, South Africa

“we want our excavators to stay within the [quad] lines. It’s like coloring, but with geo-spatial data.”

Tuesday was a warm day, with enormous waves rolling into the coastline, spray torn from the high white crests, to crash relentlessly against the rocks below. My task, week three, was to train our students as Site Techs. This is the person responsible for checking the geo-spatial data in the database, and making sure all electronic data (tablets, camera, ect) is backed up multiple times to many locations (okay, three). Capturing an archaeological site with all the marvels of modern technology is wonderful, until  something goes wrong and a computer crashes, the tablet is dropped, and a critical item is submersed in water. Every artifact has an associated data point captured by the total stations (“guns”) and associated with a unique barcode, so that we can go back and understand the “big-picture” view of the site. This method allows for precise, rapid and extensive amounts of data to be collected. Plus, it’s fun to manipulate the spatial data.

Keller et al. The Fauna of KEH-1 (South Africa) A Middle and Later Stone Age site: A Pilot Study. Poster presented at the 82^nd Annual Meeting of the Society for American Archaeology 2018.

The day before, a tablet crashed and “deleted” more than 400 datapoints (these were later recovered), causing some consternation and stress. However, this was a minor blip compared to what was about to hit us. In order to see the location of the artifact, sometimes we need to use a crosshair fixed to paper or on the end of a rod. The correct height of the crosshair from the ground must be entered on the gun, or we have points showing up in random sequences across the map. If a gunner is switching between chits and rod, it can be easy to forget to tell the computer the correct height. The day before, one of the excavators grabbed the scanner for the wrong gun, and accidently entered a find number as a rod height of 4 million (placing the points on the other side of the moon!). Luckily, fixing this involves a simple addition/subtraction, which excel preforms for us.

Once the corrections have been entered, it is time to import everything to the map and visually check the data. This is the fun part—manipulating the three-dimensional map. Then one of my site tech trainees found what we thought was a rod error: points in unexcavated sediment. We then noticed something even more problematic: all the points were shifted, not only down, but to the right of our quads. Since our crew is not given to digging in random squares, we had a bigger problem on our hands. "Transforming" the gun makes the electronics think that it has moved position relative to the triangulated position. This is useful if you want to move the gun, less so if you are marking the positions of artifacts. It took three senior members and two trainees combing through the numbers, but eventually we discovered the sequence of events:

• .       An excavator grabbed the wrong scanner, causing the gun to take a shot (i.e. collect a datapoint).
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• .       The gun reset itself to an earlier position.
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• .       All the following data collected was based off the assumption that the gun was somewhere it wasn’t.

As my stats professor is fond of saying, electronics are dumb, and people are smart. Once we knew what to look for, all we had to do was more math, mostly involving subtracting the actual coordinates from the fake ones (in the end, it required three grad students and a bottle of wine).

However cool the computer simulations are, the actual finds are just as fascinating. Holocene shell middens are a common scene along the coasts of south Africa. KEH-1 is no exception, with a dense and formidable layer of shell, bone, and who knows what else resting above the earlier deposits. (fortunately, the deposit is on a slope, so we can target the MSA/LSA transition we’re interested in). in our third week of excavation, we delved more deeply into the thick shell above. While our excavators were busily removing shell, our OLS specialist was preparing and removing samples. Additionally, we removed one of our oldest and well-placed gunning platforms, allowing us to dig deeper. So far, the stuff we have pulled from the lowest layers is not super exciting (mostly large chunks of rock and the occasional bits of charcoal. Excavators become jubilant when they discover anything else), but there is the potential for occupation layers contemporaneous with other sites in south Africa. And under the sediment, beneath the rock, is endless potential. At least until we hit the cave floor.