After more than a decade of work by a team of experts, an astounding archaeological discovery is being revealed to the Dunedin public
“It was the middle of winter in Dunedin, 2008. Wet. Dark. We had snow days.”
It almost sounds like the start of a tall story – the kind a verbose goldminer might have told, evening getting on, the hard day’s work done. But archaeologist Dr Peter Petchey is talking about his intermittent year-long project excavating the site where Dunedin’s Wall Street Mall now stands.
“It was the last day of the excavation. I’m not kidding, the final day,” he goes on.
“There were just two of us working that day. Myself, and Mark Hall on the digger. And we were digging this hole and then… we saw something.”
In some ways, Peter’s fieldwork is not so different from that of an old-time goldminer. The slow excavation of earth; the careful combing through its layers in search of treasure. Rather than gleaming metal shining through the mud’s meniscus, however, Peter’s ‘gold’ is any physical item that tells us about the past.
In this case, it was a pair of sticks.
“You get old timbers all the time,” he explains, “but these were lying side by side, parallel.”
Mark and Peter quickly found several more pieces of timber side by side, then one perpendicular, supporting the others.
The timbers were sitting about 1.3 metres below the current street level and it was obvious they had been cut with metal tools but no nails had been used, indicating that the structure had been built by very early Scottish settlers in Dunedin.
“So it turned out not to be our last day after all,” says Peter.
Six weeks after the initial discovery, Peter’s team of four, along with several volunteers, finished uncovering what turned out to be the earliest known example of a corduroy road – a timber pathway across a swampy area of ground – in New Zealand.
Built sometime between 1849 and the early 1850s, the 12-metre-long, four-metre-wide pathway has also proved to be the earliest structural evidence of settler Dunedin found to date.
It was a significant find, archaeologically and historically, because it revealed so much about the way early settlers adapted to their environment.
“The causeway represents the early settlers’ physical efforts, their growing awareness of the landscape, the establishment of the city as an agent of colonisation, and the acquisition of knowledge from local Māori, who were, perversely, being displaced by the same process,” Peter writes in an academic paper he subsequently published about the finding.
Dunedin at that time was known as ‘Mud-edin’, the area north of Bell Hill/Ngā Moana e Rua consisting largely of mudflats and swamps.
1 The first discovery of the causeway timbers, showing their axe-cut ends.
2 Jason Gay and Jenepher Glover excavating the causeway after the top metre of fill had been removed with a digger.
3 The excavation of the causeway, almost complete.
“It’s all about discovery. You never know what’s down there”
A tidal inlet also extended as far north as what is now Albion Place, adding to the boggy nature of the area. A vivid description in a 1911 book by the notorious George Hamilton-Browne, quoted in the New Zealand Heritage List/Rārangi Kōrero report on this Category 1 historic place, conjures the “rain, that not only drenched us but turned the soft loamy bush soil into liquid mud, in which we sank nearly to the knee”.
By all accounts, George tended towards exaggeration, although probably not this time. It was the mud, he explained, that “forced us to corduroy the path so as to enable the wretched pack-horses to get any footing”.
Judging by the tōtara roofing shingles that had been dropped nearby, Peter theorises the causeway was constructed in part to transport timber being felled in the bush on nearby hillsides and carried down for use in building houses in the new settlement.
“These early settlers were literally cutting a new life out of undeveloped bush,” he explains. Without the causeway, the work of transporting heavy timbers through mud would have been near impossible.
Other items were recovered from the overall site, including a badge commemorating the All-England cricket tour of 1864 (the first international sporting tour of New Zealand), a Lea & Perrins Worcestershire Sauce bottle, which looks almost identical to those on supermarket shelves today, and something that Toitū Otago Settlers Museum curator Seán Brosnahan says is “most likely a toy dog”.
Seán curated the ‘Ghosts of Wall Street’ display located at the museum, which features some of these finds as well as several hauntingly narrated stories of imagined people from the era and area. The anaerobic conditions of the site, caused by the airless mud, enabled the items’ remarkable preservation.
After the site had been fully excavated, the next stage was to remove the timbers – no simple job. Many were substantial, some weighing more than 50 kilograms.
After extensive discussions with the experts who were in consultation on the site, it was decided to uplift 40 percent of the causeway, leaving the remaining fragile timbers in situ beneath the foundations of the Wall Street Mall complex. These are now recognised within the extent of the Category 1 listing.
Next on the agenda for the uplifted timbers was a bath – and not just to clean off the mud. The goal
was to stop the degraded wood elements falling apart, explains University of Auckland wet organic conservation expert Dilys Johns.
“Oxygen accelerates decay,” she clarifies. “If the waterlogged wood is allowed to dry out without treatment, cell collapse occurs, and this is irreversible.”
The timbers were transported to a local warehouse where Dilys began her slow and careful conservation work, ensuring they would remain stable for future generations. That meant more baths, this time over several years in a synthetic, non-toxic, water-soluble, reversible wax called polyethylene glycol, which gradually replaced the water inside the degraded wood cells, allowing the timbers to be control-dried and subsequently stabilised for display and storage.
In 2018, when former archaeologist Andrea Farminer joined Dunedin City Council as Heritage Advisor, she heard of the causeway timbers, which were by then being stored in their preserved state in a warehouse outside Dunedin. Immediately, her creative neurons fired.
“I started to imagine what might be done with those timbers, in a way that would bring history alive for people,” she says.
Andrea learned that, as part of an earlier agreement between Dunedin City Council and Heritage New Zealand Pouhere Taonga following a non-compliance case on the site, the council had agreed to display the timbers in the mall, but the project hadn’t yet progressed.
Andrea picked up the cause and ran with it.
“‘Accessible’ is my keyword,” she says, referring to the potential the installation had for the public to engage easily with their heritage.
“Although,” she adds, “normally I take things out of the ground, not put things back in!”
Andrea’s initial suggestion was an installation in the ‘set down’ of the mall – a sunken area where people have coffee. Then it occurred to her that the timbers might actually be incorporated into the floor, and the floor levelled with a section of glass over the reinstated causeway, so that the public could really get a sense of walking on the causeway itself.
It’s a brilliant concept – a literal ‘window to the past’ vividly communicating the fact that our past always informs our present, although often invisibly.
Months of collaborative effort followed, with the heritage project bringing together architects, engineers, project managers, designers, research specialists and artists in what Andrea describes as “a real team effort”.
One of the most challenging jobs was to reassemble the timbers temporarily, based on Peter’s original drawings of the site, in preparation for the final installation.
“It was nerve-wracking; we didn’t want to damage anything,” says Andrea.
Scenic artist Andy King was engaged to create the mud-like setting in which the timbers would be placed.
“Andy did some amazing things in creating the backing mould,” says Andrea. “We said the wood needed to look like it was back in its mud, and that’s exactly what he’s managed to do.”
1 The causeway was reinstated in the Wall
Street Mall in July 2021, with the tiling still to be completed.
2 A close-up of the conserved timbers and the fake mud created by artist Andy King.
3 The preserved section of the causeway in place and awaiting its glass cover.
IMAGERY: ALAN DOVE
“And there’s a really great last touch,” she adds, explaining how the floor tiles adjacent to the sunken timbers are etched with the outline of the buried part of the causeway, symbolically reuniting the timbers and allowing pedestrians to walk the causeway’s full length.
At the time of writing, a tent sat over the site at the busy Wall Street Mall intersection where Andy was putting the finishing touches on his ‘mud’, evoking the slimy damp of the bog in which the timbers once lay.
All those who contributed to the project were awaiting with great anticipation the day they would be able to see the causeway for themselves.
“It will be very good to see it finished, and to see this public recognition of the value of archaeology,” says Peter. “It’s all about discovery. You never know what’s down there.”
Although in this case, of course, we do.
The preserved Dunedin Corduroy Causeway was finally reinstated in a sunken glass display in the floor of the Wall Street Mall in mid-2021, allowing pedestrians to walk over the structure almost exactly as it had been laid more than 150 years ago.