Wheelhouse Wednesday

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On Wednesday we continued our work on refining the wall lines within our structures. Cross-sections were made and drawings begun in an effort to record all aspects of our work before we begin refilling our trenches toward the end of next week. No amazing discoveries or “Eureka!” moments to report. We did continue to find pottery, flint flakes, and a few small metal objects.

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The weather was a bit hit-or-miss, and there was another large tidal surge around lunchtime, so Niall hurried us all off the island to our operations center before we were cut off from the mainland for a couple of hours. After we ate he took us to some sites where he and his colleagues have dug in the past. One of these sites was a cluster of Viking houses he and Dr. Michael Parker Pearson excavated a few years ago.

Unfortunately, as is the case all along the west coast of the Outer Hebrides, increased storm activity due to global climate change has meant that multiple meters of coastline have eroded into the sea during just the past three decades. It is hard to imagine that an archaeological site consisting of coastal Viking houses sat here on the edge of the North Atlantic for more than 1,000 years, yet within a few decades it is completely gone.

The first photo shows the results of this massive erosion. In the second photo, Niall is standing precisely where they excavated those three Viking houses before they were obliterated by the North Atlantic.

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After Niall’s visual display of just how destructive recent storm activity has been, he took us to a wheelhouse that was excavated in the 1960s by a different archaeologist. It was constructed in a hole dug into the sand, with stone slabs used to line the exterior walls.  Next, a series of corbeled archways were constructed in the interior of the house to give it more structure and support the roof. Given the spoke-like interior spaces that resemble a wheel in plan view, these structures are commonly known as “wheelhouses.” These Iron Age structures are thought to have been the typical house form in the Outer Hebrides during that period.

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Here are some photos I gleaned from the web of better persevered wheelhouses.  I’ve also included a drawing of one so you can see what the one Niall is standing in would have looked like in its prime.

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fig44Once the tide receded, we returned to the island to finish out the day.  Chelsea Kaufman, a graduate student at Yale and an exceptionally talented archaeological illustrator, suggested we try an experiment in archaeological mapping on Wednesday afternoon.  Rather than spending the 20-25 hours needed to map a mound’s exposed surface by hand, she suggested we grid the surface with string aligned to the site grid and photograph each area from above using the drone. Once recorded, these photos can then be assembled into a composite image and corrected for parallax before being put into Photoshop and each stone digitally converted into a line image. Although this method has lots of steps, it should take less than an hour to capture the final image and it promises to be more accurate than our field drawings. It would also be easier to convert the resulting image to a vector file that can then be used with a CAD or GIS program.

We decided to try it on one of our mounds, but a big debate continues to rage in our ranks around the idea that drawing by hand allows the archaeologist to understand an excavation unit in many more nuanced ways than a photograph permits. Photographs are unbiased in what they portray, but drawing by hand allows the illustrator to highlight salient aspects of an excavation unit that may have important meaning. My first professional archaeology job was as an archaeological illustrator, so I have a keen appreciation for hand drawing, but I am also a techie, so I’m open to the possibility there may be new (and more efficient) ways of recording archaeological information. Stay tuned this weekend for the results of our experimentation!

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