A layer-cake of time: Crossrail’s archaeology

Digging up part of an ancient shipwreck is usually less of a concern for London construction workers than bursting a water main. But, then again, most London construction workers aren’t employed on one of the biggest engineering projects in Europe: Crossrail. For the hundreds of men sweating in orange high-visibility clothing on the Limmo Peninsula site in east London, dealing with archaeological finds is part of the day job. In March this year, during deep excavation in the main shaft on site, they uncovered what looked like a fragment of a boat, probably dating from the 12th to 15th century. The on-site archaeologist immediately stepped in.

When you are dealing with a city as old as London, the past is sometimes only a spadeful of soil away. But for most city dwellers, the concrete means that you’re never going to get down that deep. Vast construction projects such as Crossrail, which will put 21km of new tunnels through the capital, offer a rare and valuable window into the past. Among the most extensive archaeological explorations in recent years, it is already producing finds that carve through British history: prehistoric animal bones at Royal Oak, skeletons from Liverpool Street, remains of a Tudor mansion under your feet at Stepney Green. What is more, the excavations must fit into a carefully choreographed programme that waits for no piece of pottery.

Jay Carver, project archaeologist for Crossrail since 2009, has been involved in this complex operation since 2006. A thoughtful man, who proclaims his passion for “roads and railways”, he has form on large-scale projects; he also worked on the Channel Tunnel. As he leads us on to the Limmo site, through a side door in Canning Town Tube station, the noise of enormous machinery preparing the way for the even more enormous tunnel-boring machines is deafening. “People’s perception [of archaeology] is green fields and digging a Roman villa in the countryside,” says Carver. “But in the city you’ve got this huge layer-cake of time.”

Before the construction workers even get on to these sites, archaeological assessment has formed a pretty good idea of what lies beneath. London has a wealth of helpful archival records, from birth to burial, and while there are always surprises such as the shipwreck, there is also extensive knowledge. Everyone knew that excavations at Limmo would uncover the old Thames Ironworks. Two archaeologists are busy wheeling barrows of soil away from the site of the huge Victorian shipbuilding company that founded the football club which became West Ham.

“There aren’t many occasions when you get to dig so much of London,” says Robert Hartle from the Museum of London Archaeology (Mola). “[It] is going to expand our understanding of everything from prehistory to a couple of hundred years ago. It’s a great opportunity.”

From Limmo, you can see the Olympic park, the O2 arena and modern London. But under the ground, the walls of an older structure are emerging. Charles Warner, a descendant of the last works manager before the company closed in 1912, heard about the excavation and gave Carver a beautiful coloured map which outlines where each building stood. The archaeologists are busy matching it up with the foundations – the erecting shop here, the machine shop there. “This pit looks very, very interesting,” says Carver, pointing to a dip in the ground with some rusty stains. “I find industrial archaeology very exciting because it very dramatically brings the site back to life.”

Clambering around with them, grooves in the floor become drainage systems, blocks become machinery mounts and the remains of big bolts point to long-gone objects. The old Victorian factory rises again.

This glimpse into a hidden world is going on all over the city at 22 Crossrail sites. While Londoners regard most construction projects as a nightmare of Tube delays and traffic, archaeologists eagerly anticipate them. “The whole of London is this big old jigsaw puzzle, and we’re just waiting to fill in the gaps,” says Sarah Matthews, senior osteology processor at Mola, a contractor on the project. “You knock a building down and it’s an opportunity to fill in that square of land with the history and information we get.”

Jay Carver: Project archaeologist for Crossrail, at the Limmo Peninsula site in east London

The cheery “chief bone-washer”, as she describes herself, has seen the guts of the city come through her door. “Basically, pick a street in London and we’ve dug it,” she says. Finds that arrive at the Mola warehouse typically pass through washing and drying rooms. Vases, stone balls from the tops of pillars and marmalade jars from the excavation of the Crosse & Blackwell factory are scattered around. Some Christmas decorations perch incongruously near a box labelled “human bone”. In a corner of the office, a man methodically files clay pipes. The building is full of “skellies”, as Matthews affectionately terms them – some 6,000 or so.

About 300 of them come from one of the most high-profile Crossrail finds: the skeletons uncovered beneath what will be a ticket hall at Liverpool Street. The excavation is still in its trial stage, but has already caused great excitement because the graveyard was situated on land belonging to the Bedlam hospital. Some of the skeletons may belong to former inhabitants, although nothing is yet confirmed. “Insanity doesn’t leave a physical trace on the body,” says Nick Elsden, assistant contracts manager. “At present, we can’t sort out anybody who might have come out of Bedlam from those who might have been from the parishes in the city.”

Matthews lays out a set of bones that is about 85 per cent complete. “The Crossrail bones were beautiful,” she says. “This skeleton is in really good condition.” As she waves vertebrae and femurs in the air, she sketches a picture of a young male, probably buried between 1568 when the graveyard opened, and around 1720, when it closed. Another box produces a “lovely” example of a “very nasty” fracture. The human in question lost two inches off his leg and died about a year later. “For us, it’s learning about who Londoners used to be. We can learn so much from the skeletal system; it feeds back into our medical knowledge and our nutritional knowledge and things such as the conditions people used to live in,” she says.

Sarah Matthews: Senior osteology processor – 'chief bone-washer' – at the Museum of London Archaeology

Records suggest that two celebrities might yet emerge from this graveyard: Nicholas Culpeper, a famous herbalist, and John Lilburne, a prominent political Leveller. But so far the coffin plates that might identify the residents have been too corroded to read. The only written text comes from a grave slab engraved with what looks like the name “John Bail”, a baby who died aged 25 weeks in April 1664.

However, the graves are only the beginning. It is believed that long ago flytippers also used the cemetery as a rubbish tip and, centuries later, their waste is “an important find”, revealing all sorts of worked bone. “Possible pegs for musical instruments, we’re getting turned needlecases … bits of elephant ivory and elephant teeth and tortoiseshell,” says Elsden. A pair of medieval ice-skates, made by strapping animal bones to your feet, has also emerged.

Liverpool Street is a particularly tough area to excavate because of the limited space, number of facilities and crowds of people. But, as a result, a wealth of untouched items may lie beneath. “You wouldn’t have got at Liverpool Street for any other purpose but a major infrastructure thing, because no one’s going to build on the road… and underneath there’s really good preservation, because you haven’t got foundations of things dug through it,” says Elsden. There are hopes that the next excavation down will reveal bits of a Roman road that led out to the suburbs.

When the Crossrail dig at Liverpool Street starts again the public may well remain completely unaware. “It’s surprising what Londoners don’t actually see,” says Matthews, as she recalls a previous excavation of a 2,500-skeleton graveyard. “We would be sat in a very densely touristed street and people would walk past, completely oblivious.”

About 300 skeletons were found at Liverpool Street – this one is 85 per cent complete

Part of this is due to the way in which archaeology is now seamlessly woven into the larger construction project. London has always thrown up gems. The Victorians who dug the first sections of the Underground filled much of the Natural History Museum. But assessing, recording and, in the most valuable cases, preserving what was discovered was not formalised until much later.

Along with the layers of history, archaeologists are now adept at layers of bureaucracy. Planning for the Crossrail project started in 2003, six years before the main programme of investigation began. The process involves two contractors – Mola and Oxford Archaeology – and numerous specialist scientists to work on the uncovered finds. “It’s a massive cut through London,” says Richard Brown, senior project manager from Oxford Archaeology, whose career has seen archaeology becoming a formal part of the planning process. “A lot less is being lost. A lot more is being recovered.”

“We’ve become part of the same system,” says Jay Carver. “It’s all sorted out – who needs to do what and where.” When the boat fragment was uncovered in Limmo, it was recorded and lifted out in a single day, and will now go through dendrochronology [tree-ring dating] to try to establish a precise date. Archaeologists may work over the weekend or holidays to finish before the machines move in, but no one would now think of ploughing on without consulting the experts. “We have a voice now, due to generations of engineers and archaeologists working together,” he says.

Simon Parfitt: Researcher in vertebrate palaeontology, at the Natural History Museum, London

Simon Parfitt’s involvement with the project began when his phone rang at the Natural History Museum in May last year. Some Pleistocene-era animal bones had been discovered at Royal Oak Portal. The researcher in vertebrate palaeontology popped round to take a look. “We were blown over by the excavation … just the logistics of actually digging the site is quite exciting.” If you look out of your train window coming into Paddington, you can almost see the space where several hundred bits of these ice age bones were dug up. “The really surprising thing is that London is the most intensively investigated area for archaeology, but it’s continuously throwing up surprises,” says Parfitt. “Royal Oak Portal was one of those surprises – a hugely important site, which they weren’t expecting, and they had to deal with that … because the machines were booked to start drilling.”

For Parfitt, London is a map of landscapes past. Talking to him, you can still see the hippos and elephants romping on the terraces of Trafalgar Square. “Finchley Road is as far south as the ice sheet got,” he tells me, as he talks about using finds from the Thames to reconstruct periods about which very little is still known. “The great thing about this site … is that you’ve got detailed information on the context, the position of pieces in the ground, the geological context and dating evidence.”

The Natural History Museum arranges its stored materials by location, but the Crossrail collection doesn’t currently fit in the London cabinet. Instead, Parfitt fishes them out of an “odds and sods” cupboard. Reconstructing the past is never easy, but when the bones in question are crushed into hundreds of fragments from thousands of years at the bottom of a river, it can be quite a task. A volunteer painstakingly pieced them all together, glueing on new bits as she went. After comparing them with other reference collections at the museum, Parfitt determined that they were dominated by small bison and reindeer remains. This enabled him to date them to a relatively short period 80,000 years ago when this combination existed. “The really exciting thing is that it’s recording a major change in the climate,” he says.

A baby’s grave slab from 1664

Compared to the scale of the tunnel-boring machines that will gouge through London, a small bump on the hind-foot bone of a long-dead bison might not seem much. But, as Parfitt explains, it contains a whole history, pointing to the stress inflicted on animals by migration. “The only reasonable explanation is that the bison are moving in huge herds above the landscape,” he says. The initial theory that the bones might have shown human interference is wrong, although there are gnaw marks possibly left by wolves.

Parfitt believes further analysis may reveal still more. “I thought there had to be other material from that part of London, but there’s nothing… so the collection will hopefully stay here,” he says. And, with two more years of excavations to go, there could be many finds to come. Some will be housed in museums or archives. The bodies will be reburied or kept for analysis. Many Crossrail sites will simply be recorded for posterity before the diggers come in, erasing one layer of history to lay down another – and putting down tracks for future archaeologists to dig up in their turn.

Alice Fishburn is deputy editor of FT Weekend Magazine

A free, one-day exhibition of the Crossrail discoveries will be held on July 7 at Grays Antiques, 26 South Molton Lane, London

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