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painting of fishing boats off Newfoundland
For centuries, European boats that fished the Atlantic’s Grand Banks left their stone and gravel ballast on Newfoundland’s shores. Photo by Josse Christophel/Alamy Stock Photo

How Bomb Debris from Bristol, England, Made a Road in NYC

Solid ship ballast from the age of sail tells surprising stories about history.

Authored by

by Mats Burström

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Just when we thought we knew everything important about the age of sail and its impact on the world, along comes research that exposes our collective myopia when gazing at the past. Ships carried all sorts of things across the oceans, including commodities, disease, and ideas. But as archaeologist and author Mats Burström shows, ships also scattered bits of their homelands—quite literally—around the world.

Today, ships use water as ballast, in the process delivering microscopic organisms to international ports. But once upon a time, mariners relied on solids—bricks, stones, and gravel—to lend their ships stability. In four centuries of sailing, they left millions of tonnes of material around the globe from Canada to India.

In this excerpt from his new book Ballast: Laden with History, which has its North American release this week, Burström reveals the surprising story of ballast and considers its place in archaeology. Is historical ballast an artifact or a natural object?

Stones and Beetles in Newfoundland

Here and there along the shores of the island of Newfoundland there are large amounts of flint. Since flint does not occur naturally in the area, we know that it was once ballast. This is what remains of the vast seasonal Grand Banks fisheries, so important from the early 16th to the early 20th centuries.

In Eurocentric terms, Newfoundland was discovered in 1497 by John Cabot, a Venetian-born navigator sponsored by King Henry VII of England and a group of Bristol merchants. By that time, of course, there had been people living in Newfoundland for a good 9,000 years, and we also know that around 1000 CE there was a short-lived Viking settlement at L’Anse aux Meadows at the northernmost tip of Newfoundland. As recently as 2015 a second possible Viking settlement was identified at Point Rosee, at the southwestern end of the island.

Cabot’s “discovery” of Newfoundland and the huge stocks of cod in the waters of the Grand Banks had a direct impact on Europe for centuries to come. The demand for dried or salted fish in the Catholic countries of Europe made cod a valuable commodity. This rich resource was exploited first by the French, Spanish, and Portuguese, and later mostly by fishermen from the British Isles. About 350 ships are believed to have joined in the seasonal fisheries in the 16th century, although there are contemporary data that indicate a much larger number.

The fishing fleet arrived in Newfoundland in April or May and sailed home to Europe in October. With the exception of a small number of people who were left behind to look after the fishermen’s investment—jetties and fish flakes, a type of rack for drying fish—Newfoundland was left largely uninhabited by Europeans in the winter months, and it was only in the early 17th century that the first permanent settlements were established. This meant that the fishing fleets that arrived from Europe had no local markets to supply with merchandise, and as the crews’ stores did not make up a full load, the ships had to add ballast, sailing “in ballast.” When the ships returned home in the autumn, they were laden with fish and had little need for ballast. As a rule they did not sail straight to their home ports, but instead made first for the Catholic countries of southern Europe, where the demand for dried or salted fish was greatest. From there they returned then to their home ports having taken on wine, salt, and other marketable goods—and perhaps new ballast. This triangular trade has been neatly summarized as turning fish into wine.

Ships aground at North Devon, England, circa 1900, take on sand and gravel as ballast. Photo courtesy of the National Maritime Museum, Greenwich, London

Ships aground at North Devon, England, circa 1900, take on sand and gravel as ballast. Photo courtesy of the National Maritime Museum, Greenwich, London

The size of the fishing boats increased from an average of 50 to 100 tonnes in the 16th century to double that or more in subsequent centuries. In the early 19th century, the ships leaving Britain for the Grand Banks fisheries carried an average of 50 to 70 tonnes of ballast. Given the number of vessels involved in cod fishing over those four centuries, it is evident that very large amounts of ballast crossed the Atlantic. An accurate figure is impossible, but supposing that 350 ships each offloaded 25 tonnes of ballast every year for 400 years, then 3.5 million tonnes is a not unreasonable number. Whether this is a high estimate or a low one cannot be said with any certainty, but either way the sheer quantity of ballast must have left its mark on Newfoundland.

Large quantities of ballast flint have been found at archaeological excavations across Newfoundland, including in Ferryland, a British settlement dating from 1621, where an extensive study has been underway since 1992. On excavating a wharf-like structure, they found oak barrels of flint gravel and sand that had presumably been used as fill. Among this was found what is thought to be the tip of a Paleolithic tool, which would have arrived in the ballast from Europe.

In Ferryland, as at other sites in Newfoundland, ballast flint had been used as fire strikers and gunflints. Both objects were essential to everyday life in the early modern period, and even though finished gunflints were imported from Europe, ballast flint was still a welcome addition. There is also a find of an arrowhead that is thought to have been made from flint ballast by the Beothuk, the Indigenous people of Newfoundland.

Ballast flint from excavations in Ferryland, Newfoundland with a centimeter scale for reference

Ballast flint from excavations in Ferryland, Newfoundland with a centimeter scale for reference. Photo by Mats Burström

A flint scraper found on a beach at Grandois in northern Newfoundland during an archaeological survey hints at some interesting possibilities. It is thought to be a Beothuk-made tool fashioned from European ballast flint. If that assumption is correct, then it dates to between 1500, when the European fishing fleets first arrived in Newfoundland, and 1650, when the Beothuk switched to using tools made of reworked European iron. The iron was taken from the Europeans’ fishing camps when they were left unoccupied in the winter months. An alternative reading by Peter E. Pope, the archaeologist who found the scraper, is that it was instead a Paleolithic artifact that had arrived with the ballast from Europe. Whichever interpretation is correct, the scraper is silent testimony to the way ship ballast can challenge all the stereotypes of an object’s “proper place.”


In Newfoundland, as elsewhere, it has been assumed that the color of the flint is an indication of its origin. The accepted line is that gray or black flint comes from England, and pale brown or honey-colored flint from France, yet this is not particularly reliable. However, there are other, more surprising ways to track ballast’s origin.

The Swedish entomologist Carl Lindroth studied the spread in North America of plant and animal species that originated in Europe, and found that Newfoundland is the part of North America that has by far the largest proportion of introduced species. The 19 species of ground beetle (Carabidae) are a case in point. They are especially prevalent in the Avalon Peninsula on the east coast of Newfoundland, which is where the seasonal fisheries were concentrated. Subsequent studies have confirmed Lindroth’s findings. The same has also been found to be true of plants with a European origin—they mainly occur around the harbors used for the seasonal fisheries.

Lindroth was intrigued by the fact that the same species of ground beetle can produce both short- and long-winged individuals. The latter spread more readily, which means that the greater the proportion of short-winged ground beetles, the greater the likelihood that they had been there a long time. Again, it transpired that short-winged ground beetles predominated in the eastern part of the Avalon Peninsula. This distribution pattern coincided with the sites that the European fishing fleets had used the most.

This realization led Lindroth to study the historical record of the European trade with Newfoundland in considerable detail. He demonstrated that huge amounts of ballast were shipped across the Atlantic and then disposed of. As early as 1611 there were regulations prohibiting the dumping of ballast in a way that could obstruct harbors. The ban was reiterated in a succession of 17th- and 18th-century regulations, which required that ballast be taken ashore and left where it could not do any harm. Lindroth concluded that it was the transatlantic movement of ballast—with plant seeds and insects inadvertently included—that explained the presence in Newfoundland of a large number of animal and plant species of European origin.

Big-eyed Bronze Ground Beetle (Notiophilus biguttatus)

Solid ballast often inadvertently carried organic hitchhikers—including plant seeds and insects such as this ground beetle—between continents. Photo by Richard Becker/Minden Pictures

To better understand ballast’s part in the introduction of new species to Newfoundland, Lindroth broadened his study to include the coastal regions of southwest England, where most of the European fishing fleet was based. Lindroth found that of the ships departing the English port of Poole over a 12-month period in 1813 to 1814, fully 38 were bound for Newfoundland, of which 21 were partially or fully loaded with ballast, with the total amount of ballast exceeding 1,100 tonnes.

Lindroth examined the spread in Europe of the species of ground beetles that were introduced to Newfoundland in ship ballast. He found that all species were present in the places where ballast was taken in southwest England, and therefore they probably also originated from the region. It would seem that beetles are a better indicator of the origins of the ballast found in Newfoundland than is the color of flint. The fact that the presence of so many animal and plant species is the result of the past movement of ballast begs the question of what qualifies as archaeological source material in the first place. Animals and plants are not in any sense artifacts—they are not created by people—but nevertheless their presence is a direct consequence of human actions in the past.

Rubble Crossing the Atlantic

Along East Manhattan’s shoreline in New York runs Franklin D. Roosevelt East River Drive, a six-lane highway usually referred to as FDR Drive. Part of it is built on fill consisting of the ruins of a bombed medieval town—Bristol in southwest England. The rubble had crossed the Atlantic in the Second World War as ballast in the Liberty ships returning to the United States having delivered materiel and supplies to Europe. Commemorating what lies hidden under the road surface, that stretch of the riverbank is known as Bristol Basin.

Bristol was the victim of massive German bombing raids during the Second World War. The Bristol Blitz, which lasted from November 1940 to April 1941, claimed some 1,300 lives and damaged more than 89,000 houses, of which about 82,000 were destroyed. The bombing left central Bristol devastated and changed it beyond all recognition. When the then mayor of Bristol, Thomas Underwood, looked back on the heaviest German bombing raid on November 24, 1940, he said, “The City of Churches had in one night become the city of ruins.”

The scale of the German attack was so great because Bristol was both a major port and an industrial center, and its aircraft factory was an especially important target. Bristol’s position on the southwest coast, with excellent communications with the rest of the United Kingdom, made the city an ideal first port of call for ships crossing the Atlantic. It was where the Liberty ships loaded with munitions and supplies came into the port.

The war produced a high demand for cargo ships, so a new, simple design with a carrying capacity of about 10,000 tonnes began to be mass-produced in the United States. They were dubbed Liberty ships after President Roosevelt announced at the launch of the first that they would bring liberty to Europe. Over 2,700 were built with a life expectancy of only five years.

Once unloaded in Bristol, the Liberty ships needed to take on ballast for the return trip to the United States. Unlike most other ships of the time that used water for ballast, Liberty ships largely relied on solid material. The demand for ballast was huge—each ship required 1,500 tonnes—and the answer was to use the rubble from the shattered city center. From central Bristol, the debris was transported about 10 kilometers down the River Avon to Avonmouth Docks at the mouth of the river.

Air Raid Damage Bristol Civilians searching through rubble of their bomb damaged houses after an air raid on Bristol

Liberty ships carried much needed supplies to Europe, and returned home with bricks and other debris from the destroyed town of Bristol, England, as ballast. Photo by Trinity Mirror/Mirrorpix/Alamy Stock Photo

Despite the amount of ballast moved across the Atlantic, the full extent of the operation is almost unnoticed in the historical record. The tangible remains survive, though, if hidden from view.

When the Liberty ships docked in New York, the first thing they did was to deballast. The ballast had served its purpose and so was tipped as fill along Manhattan’s eastern shore. Reinforced with concrete pilings, this new ground was soon built over with roads and buildings.

Even if hidden from view, the rubble still holds up part of New York to this day, including parts of FDR Drive. Elsewhere in the Big Apple, archaeological digs have uncovered flint and coral that arrived as ship ballast from Europe and the Caribbean and was reused as fill.


Mats Burström is a professor of archaeology at Stockholm University, Sweden. In his research he takes a fresh approach to previously overlooked remains from the past, revealing how they display history in a new light. Even seemingly trivial objects hold fascinating stories. In his writings, Burström draws on his wide-ranging archaeological expertise to explore the significance of objects for memory construction and remembering.

A previous version of this article stated that the Viking settlement at L’Anse aux Meadow dated to around 1000 BCE. It dates from around 1000 CE.