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Archaeologists' most exciting finds:
Knut Paasche was incredibly excited when he found something truly special from the Middle Ages
He initially had no idea what he had found on that day in the 1990s. It turned out to be a large medieval Nordic sailing ship. But it wasn't from Norway.
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“That find was a big deal. I walked around with a spring in my step for several days afterwards, and I thought it was incredibly exciting,” says Knut Paasche.
Paasche is describing the period following a discovery he and his colleagues made in the early 1990s.
He is an archaeologist and heads the department of digital archaeology at the Norwegian Institute for Cultural Heritage Research (NIKU). Paasche has worked extensively with Viking ships and historical boatbuilding techniques.
In 1992, he led the investigation beneath the old container terminal at Sørenga in Oslo. Today, new apartment blocks extend along the pier towards Sørenga Seawater Pool, but at the time of the excavation, this was an industrial area.
People had lived, unloaded cargo, and worked there for more than a thousand years, but very little of the archaeological history had been investigated.
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"We hoped to find something from the Middle Ages, especially something related to the harbour," says Paasche. “The very first thing we found was a ship made entirely of oak.”
"I didn't know anything about boats"
Oak is known as an extremely durable type of wood, and both the Oseberg and Gokstad Viking ships were built from oak.
But it was not immediately clear that the find was actually a boat.
Today, Paasche is one of Norway's archaeologists with the most experience studying Viking ships and other prehistoric vessels, but at the time he was still relatively new to the field.
“I grew up in Norway's inland eastern region and didn't know anything about boats, so I stood there looking at this plank that had appeared and didn't quite know what I was looking at,” he says.
Another archaeologist pointed out that it had to be the plank of a ship. They soon found many more long ship planks made of oak.
The ship dates from the Middle Ages and was given the name Sørenga 2.
This was the second ship discovered at the site. In the following years, archaeologists unearthed several more medieval ships in the same area, as documented in this NIKU publication on the excavations at Sørenga (link in Norwegian).
The ship turned out to have the potential to rewrite an important part of history, according to Paasche.
A medieval sailing ship
The ship has been dated to 1355. The dating can be this precise through the use of dendrochronology.
Dendrochronology is a dating technique where researchers can compare tree rings from many different trees across many centuries.
That makes it possible to trace the timber used in the ship to very specific years.
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Sørenga 2 is a clinker-built ship of the Nordic type from the Middle Ages. We’ll come back to that.
Paasche explains that it was a partially open cargo vessel with a small deck at both the front and back. It probably did not need a large crew to sail it.
The sail could be raised or reefed using a capstan, a type of winch, which made the job easier.
That was different from the Viking ships built a few centuries earlier, which required larger crews for both rowing and sailing.
A gap in history
So, getting back to clinker-built ships like the Sørenga 2.
This was a Scandinavian shipbuilding technique that has been in use for several millennia, since at least around 200 CE.
All the large Viking ships were built in this way, and they were capable of sailing long distances across the open sea. That was one of the foundations of the Viking Age.
Clinker construction is characterised by ship planks that partially overlap one another to make the ship watertight. The planks are fastened together with iron rivets, according to the Great Norwegian Encyclopedia.
The discovery of such a large clinker-built ship from this period in Oslo was highly significant, according to Paasche.
Very few traces of such large ships built in this way – in the 14th century, several hundred years after the Viking Age – have been discovered.
“People had assumed that the Viking ships had become obsolete. They weren't well suited for carrying large cargoes, and clinker-built Viking ships were no longer considered particularly practical,” says Paasche, adding:
“I knew there was a gap in the historical record here. It took me a day or two before I realised that an important piece of the puzzle was about to fall into place.”
The discovery made a lasting impression
“It has to be the most exciting thing I’ve ever experienced,” says Paasche. “The discovery really launched my career. I’ve worked a lot with ships since then.”
He explains that historians had thought that the German Hanseatic League and their ships dominated trade between Norwegian towns and between Norway and the rest of Europe during this period.
But it turns out that there were also large Nordic clinker-built ships being used for cargo transport at the time. A similar ship has been found in Bergen, along with several other archaeological discoveries made later. Paasche argues that these findings have created a more nuanced understanding of trade and shipping in medieval Norway.
“We now know that there was extensive traffic on Nordic-built ships sailing throughout Scandinavia and to Germany and England during the Middle Ages,” he says.
Paasche believes there was a considerable amount of Norwegian trade that operated independently of the ships belonging to the powerful Hanseatic merchants.
The ship was deliberately sunk
The preservation conditions were excellent, so the planks remained remarkably intact. A large portion of both the hull and the keel survived.
The ship was not lying there because it had been wrecked in an accident. It was found alongside several other ships because a large wharf was being constructed at the site.
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“The wharf could rest on top of the ships. So this was a wreck that was deliberately sunk,” says Paasche.
But the ship wasn’t built in Norway.
When the researchers examined the wreck, it became clear that it had been built in what is now Sweden.
“It was most likely built in Bohuslän or southern Sweden,” says Paasche.
This conclusion is based both on the tree-ring patterns in the oak timber, which match trees from that region, and on pollen analysis.
In the overlap between the ship's planks, spun wool soaked in tar was packed in to seal the seams. That material also trapped large amounts of pollen from many different trees and plants.
“So we can see almost exactly where the ship was built, because we don't have that pollen composition along the Norwegian coast,” says Paasche.
So this was a Swedish-built sailing ship from the Middle Ages that lay buried beneath a container terminal in Oslo for many centuries – until Knut Paasche brought the ship's planks out of oblivion.
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Translated by Ingrid P. Nuse
Read the Norwegian version of this article at forskning.no
Here are more of the most exciting finds made by archaeologists
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