Sarah Mallet calls herself a “normal” archaeologist. An expert on how English diets changed between the iron age and the medieval period, she is a member of a discipline whose bread-and-butter work might involve recording and dating, say, Saxon fibulae. But today, at Pitt Rivers anthropological museum in Oxford, she is holding out for inspection not of an ancient coin or a shard of prehistoric pottery, but a decidedly modern teargas canister.

“I’ve recorded quite a few of these,” she says. “This one’s dated 2009, which means it must have been out of date by the time it was used. Some of the ones I’ve seen as are old as 1998 – and teargas gets more potent over time. There are a lot from 2015 and 2016.”

Together with her Oxford University colleague Dan Hicks, Mallet has been working on the archaeology of the near present – specifically, that of the Calais refugee camp of tents and shelters that, between March 2015 and October 2016, became the dwelling place for thousands of displaced people, mostly from Afghanistan, Eritrea, Ethiopia and Sudan, all desperately attempting to reach the UK.

Facebook Twitter Pinterest Road map … a canvas banner painted with the nations of a group of displaced people. Photograph: Ian R Cartwright

The fruit of this work – undertaken with activists, artists and people who lived at the camp, which became known as “the Jungle” – is a new exhibition at Pitt Rivers. On show are artefacts and artworks salvaged from the camp, as well as photographs, drawings and digital maps that document its existence on a former rubbish dump on the eastern fringe of Calais. One wall is dominated by a giant banner, which inhabitants painted as a map showing their own countries – Syria, Iran, Afghanistan. Britain is a tiny, perhaps unattainable, outline in the top left-hand corner.

What if all around us, now, there are prehistories, unwritten lives?

Hicks explains the approach. The boundaries of archaeology, since it became an academic discipline in the 19th century, have been gradually inching forward to encompass not just prehistory or the ancient world, but medieval archaeology, industrial archaeology and the archaeology of conflicts such as the first world war. The idea is that the written record never reveals everything: artefacts, material culture and changes in landscape can tell a deeper story, enriching our knowledge of the past in new ways.

“But what if there is something we could call the undocumented present?” says Hicks. “What if all around us, now, there are prehistories, unwritten lives? There is an archaeological method that isn’t only about digging.”

Facebook Twitter Pinterest Devotion … the Calais Cross, salvaged from St Michael’s Eritrean Orthodox Church before it was demolished.

All the items in the Pitt Rivers show are on loan from activists, artists or former inhabitants. There is a simple, blue-painted wooden cross that had been part of the Eritrean church, which the bishop of Bangor salvaged before the camp was destroyed by French police in 2016. There is a painting of a penguin, made by an unaccompanied 15-year-old in the camp called Razhan who is now safely in the UK. The image, created in a workshop run by British artist and co-curator Sue Partridge, is surprisingly jaunty, though the flightless bird is depicted out of its normal habitat, in a sunny landscape.

Most movingly, for Hicks, is a paper cutout of a child, a six-year-old called Daniel, who was in the camp with his father. This is one of the “paper people” Partridge and others made with the camp’s children, drawing round their bodies, and painting the cutout figures. Before the southern section of the camp was destroyed in March 2016, 291 unaccompanied children were living there; afterwards, 129 were reportedly missing. The “paper people” were made to commemorate them. Today, Daniel’s whereabouts are also unknown.

“It’s a kind of sculpture,” says Hicks. “Part of the idea is having papers, the thing that makes you human, or not.”

Facebook Twitter Pinterest Dehumanising … a child wanders through the rubbish-strewn Jungle camp. Photograph: Caroline Gregory

Archaeology, though, is about more than the amassing of objects. It is also a way of thinking and, to Hicks, “it was obvious that archaeology would have something to say about the Jungle. Archaeologists are real nerds, right? We record things, describe things, draw things.”

The documentation of teargas canisters might fall into that category. “Archaeology,” says Hicks, “records all that: the truncheon used at the height of the trouser pocket, in order to break a mobile phone, the removal from a person of a single shoe.” These things on one level are banal and ordinary, but at another are terrifying. Archaeology is also about tracking changes in how a landscape is used. In this case, Hicks was fascinated by “the use of the environment as kind of weapon against the weak. The alteration, the building of fences, physical violence and threats, the tactics of trying to keep people away from Calais.”

Perhaps most striking is the way Hicks and Mallet place the Calais camp in the context of a long line of oppressive, dehumanising border arrangements, from the peace walls of Northern Ireland separating Catholic and Protestant areas to the putative US-Mexico wall. In their book Lande: The Calais “Jungle” and Beyond, they write: “Archaeologically, this global wall-building moment is unprecedented: whether in Texas, Norway, Israel or India, the change isn’t just a question of scale, but of the increased militarisation of national borders that exclude, and in doing so create human populations that are categorised as ‘illegal’.”

They compare these modern barriers to the English country estate wall, the bricks-and-mortar technology that kept the riffraff off the gentry’s land: “Now wrought in steel and razor wire, [the wall] appears to be emerging as the signature artefact, archaeologically speaking, of the geopolitics of the nation state.” They insist on the notion that Calais – for two centuries an English town until it was lost to France in 1558 – is the UK’s meaningful southern border, rather than Dover. It was also the physical manifestation of political policy. They see the camp as “an articulation of the ideology of the ‘hostile environment’”, Theresa May’s stated border policy from 2012, when she was home secretary.

Facebook Twitter Pinterest The Wind Will Take Us Away (باد ما را خواهد برد) by Majid Adin, commissioned for the Lande exhibition, 2019. Photograph: Majid Adin

It is no coincidence, argues Hicks, that most of the people who came to the camp, all desperate to get across the Channel, were from parts of the world that came under a British sphere of influence or protection in the late 19th and early 20th centuries. The origins, they say, go back centuries, right back to that time when England lost Calais – and slowly embarked on acquiring an empire.

We haven't thought about the later phases of empire, people who have lived in war zones for 100 years. This isn't part of our national conversation

We may have been outraged by the injustices inflicted against the Windrush generation, but Hicks says: “We haven’t thought about the later phases of empire, the informal empire, people who have lived in war zones for 100 years, on or off, the human casualties of that. This isn’t part of our national conversation. It’s a gap in our vision.”

When the camp was seemingly destroyed, mini versions of it sprang up in different places. The situation for refugees and migrants at Calais is still desperate. For Hicks and Mallet, the Jungle was not an event, not something that existed in a single time and place, but part of a process – one that is not over. In fact, it may be only just beginning.

• Lande: The Calais “Jungle” and Beyond is at the Pitt Rivers Museum, Oxford, until 29 November.