One by one, the archaeologists came across bits of junk. Using techniques typically reserved for documenting stone tools and bones, the team recorded things like plastic spoons, glasses, bottle caps, straws, cell phone batteries, paint cans, candy wrappers and plastic wrap. By the time the experiment was over, the archaeologists had discovered nearly 3,000 objects, the vast majority of which were plastic.
That plastic would be found on the site, a former hillfort in Wales, was no surprise. In fact, it was expected, but not to this extent.
Since the 1980s, the site has been home to two Iron Age replica roundhouses, which correspond to the houses that once stood in the Iron Age fortress of Castell Henllys at the end of the first millennium BC.
Most of the visitors who came to the site were children on a field trip, the legacy of which is only now becoming apparent. Like the new antiquity paper shows, plastics have a habit of hanging around – including on heritage sites that existed long before these synthetic materials were invented. It is yet another sign that we have entered the Anthropocene, a period when we are remaking the planet in our image.
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The replica roundhouses in Castell Henllys served two different purposes. The first, called the Cookhouse, was set up like a true Iron Age roundhouse, while the second, called Earthwatch, was set up like a classroom, where students sat on benches to learn and eat their snacks.
Pembrokeshire Coast National Park, which manages the site, recently decided to dismantle the roundhouses to health and safety issues. However, prior to building new structures, archaeologists thought it wise to excavate the site. It would be a good opportunity to study decay processes, to determine which human activities result in residual waste and how replicated structures can affect the integrity of prehistoric structures in the same location. Here, the two replica roundhouses were literally built on the same spot as the real ones that existed over 2,000 years ago. As the authors wrote in their study, “We expected that the artifact assemblies and distributions in Castell Henllys could serve as valuable tests for correlating inadvertent discards with activity patterns.”
This turned out to be the case, but the amount of waste seen at the site exceeded them expectations.
“We often find a small amount of recent debris at the start of an excavation, or when we find an intentional dump site, but never in a Grade II listed or occupation building like this,” said Harold Mytum, an archaeologist at the University of Liverpool and the first author of the new newspaper, explained in an email.
This is not to say that the heritage site was poorly managed. The round houses were regularly cleaned to maintain the look and feel of a prehistoric Iron Age. But as the new research shows, a surprising amount of litter managed to crawl into the ground, leading to the discovery of so many items. Needless to say, the vast majority of items recovered were found in Earthwatch, true the students ate their snacks. Most of the items were small and patchy in nature, such as torn parcels, which explains why not all waste was collected.
“Pack-ups for kids [lunch packs] can damage the planet – they contain a lot of plastic and objects fall and get lost, ”said Mytum. “Candy wrappers are also plasticized and pose another threat to the environment.”
Needless to say, the discovery of all this plastic, while certainly part of the experiment, forced archaeologists to change their approach. The scientists had recorded all the finds, but they had to adjust their resources “to do the evidence justice,” Mytum said. That said, it didn’t affect the archaeologists’ ability to investigate how the buildings had deteriorated over the decades and to the document the various signatures left by our modern civilization.
“Indeed, it revealed how artifacts are processed in the floor and also where they were closest in the houses,” explains Mytum. “Prehistoric houses have fewer finds, but we can think about how activities leave their mark in archeology.”
Looking ahead, Mytum and his colleagues will continue to work with Pembrokeshire Coast National Park to educate the public on these matters and to find more effective ways to keep these important spaces clean.
But it will not be easy.
“Even rural, well-managed sites can have a significant build-up of plastic in the soil,” said Mytum. “The plastic age – an indicator of the Anthropocene – has indeed come not only to the oceans of the Blue Planet, but also to the bottom. Reducing the use of plastic is essential – this debris was a by-product of our lifestyle, even in a place where clearly modern materials, such as plastic waste, are being cleared away so as not to affect the heritage visitor experience. “
To which he added, “If things get that bad here, it’s a sign that our lifestyle needs to be rethought.”