Amsterdam Dug Up a River to Build a Metro Line, and Stumbled Into a Journey Through Urban Archaeology

The stories behind 700,000 objects add up to Amsterdam

On July 22, Amsterdam opens a brand-new metro line, the North/South line. In the main river channel it runs along, archaeologists have dug up roughly 700,000 objects that trace the city from prehistory to the present. Twenty thousand of them have been arranged by year on a website for anyone to browse — or to make collages out of.

The 700,000 finds came out of the Amstel, the river that gave the city its name, and they are mostly everyday things. The website, Below the Surface, shows 20,000 of them, spanning 124,000 BCE to 2005. From the past century there are mainly coins, keys, credit cards and bottle caps; go back further and there is more ceramic and metal, along with the occasional cup, cloth so faded its color can no longer be told, and shoes beaten out of shape; earlier still, the finds are mostly bones. Because the river once had trading ports along it, they also include intact shipwrecks and ship parts.

Ceramics account for the largest share, more than 350,000 pieces, followed by bone (126,000), metal (92,000), leather (59,000), white clay (26,000), glass (21,000) and architectural ceramics (10,000). Jerzy Gawronski, professor of archaeology at the University of Amsterdam and head of the archaeological team, says most of the objects either fell in by accident or were thrown in as rubbish by residents and visitors of one era or another, and that the vast majority cluster where people historically gathered along the river — at bridges and docks.

Click a photograph and you also get the object's material, function, size, weight, date and find site. Before long the site will offer downloadable data on all 700,000 finds. "People can have these original images and combine them and search them however they like," Gawronski told QDaily. "It's a model of freedom and democracy."

People assume archaeology is about old and lordly things from temples and castles, he says, but an object's importance has no necessary connection to its price or its rarity. What matters is how it relates to other objects, and whether together they can tell a good story about the past. What his team is showing is the history of ordinary people — and the material history of how Amsterdam grew.

"This river is our museum. We have opened up everyday life from the past," he says.

Gawronski spent 15 years on the fieldwork, the research that followed and the publications, and he came to the project as head of the archaeology department of the Amsterdam city government. It began in 1996, when the city council decided to build the North/South metro line. From the earliest planning the project weighed what the construction would mean for archaeological research, so that historic objects along the route — including in the Amstel — would be protected. So from 2003, when digging for the metro started, archaeologists worked alongside it on the riverbed, 12 to 30 meters underground. They had to fit in with the metro works, and the money the Dutch government put up for the archaeology came out of the metro budget too: 6 million euros in all.

The team, Gawronski says, included archaeologists, materials scientists, geologists, conservation specialists and geographic information system (GIS) experts, with students, volunteers and other specialists joining at times — more than 100 people in total. The work covered assessment, collection, recording, testing, classification and academic research, carried out on the riverbed and in the lab.

The river

What makes the project unusual, according to the website, is not its scale but its terrain. Underwater archaeology took off in the 1960s, and the many remains later recovered from water and riverbanks settled the scientific value of water as an archive. Even so, rivers are rarely chosen as sites. Here the metro works required the water along the route to be drained, which made the Amstel easy to examine.

More important, the river's own character handed the Amstel an enormous number of finds. It flows slowly and its bed is soft silt, so anything that sank into it was unlikely to be washed away. In open water, meanwhile, large quantities of material settle to the bottom and end up piled together — from wrecked bicycles to scraps of metal — so the dredgers usually came back full.

Amsterdam began to be a major trading center in the 12th century. Over the following centuries the ships passing through and the people living there left traces that belong to no single era and no fixed patch of ground. The ceramics, bones and metal objects dropped or discarded in the river over that time are random, Gawronski says, but taken together they map the city's daily life and material culture over the long run, and help build up a picture of its history.

Geology and culture

This was an interdisciplinary dig, in Gawronski's account. The research aimed at landscape and city, which correspond to the two elements of urban archaeology, geology and historical culture: the meaning of the landscape shows up in the physical facts of its geology, the meaning of the city in its historical culture.

Geology studies natural indicators — landscape, ecology, climate. Specialists examined sediment, shells, diatoms, pollen, seeds, animal bones and other geological remains from the bottom of the Amstel, and studied the climate and environment since prehistory to work out how the river had changed. The river's thick layers of sand and clay, and above all the cross-sections of deep subsoil, yield a great deal of geological information, reaching back long before the city existed.

The soil that now makes up the dikes, for instance, only began to form in the 5th century BCE, considerably later than in other European countries. The soil layer 12 meters down belongs to the youngest geological epoch, the Holocene, which began around 10,000 BCE; the peat bogs and marshes formed in that period gave rise to farming settlements in the Middle Ages, and Amsterdam was founded around 1200 CE.

Historical culture, on the other hand, is studied mainly through the objects people made. As long as it makes headway on how objects relate to the structure of the terrain — that is, how the remains relate to urban space — archaeological research can fill gaps left by history, Gawronski says. The questions to ask include: what does an object mean in space? What did a particular place do in the city's history?

At Nieuwe Brug, for example, the team found large numbers of bones used for throwing games, which shows the spot was a popular place for children to play in the 16th and 17th centuries. At another bridge, 79 daggers and dagger parts (49 of them "ballock daggers") suggest brawls broke out there often.

"What an archaeologist finds is not a plate — it is its meaning within history," Gawronski says. "Urban archaeology is a new way of telling history."

The finds sort out how Amsterdam developed. Food remains and objects such as tools and vessels show that people settled along the Amstel at least as early as the late Neolithic and the early Bronze Age (2700-1800 BCE). From Roman times through the Middle Ages a few people lived there, but not many. Only in the late 12th century, probably because of climate change and falling sea levels, did settlements appear in this area. Scattered dwellings then grew into villages and towns, which used the sea and an abundance of waterways to trade worldwide.

All the spatial and geographic information was fed into GIS software to build a detailed 3D model. The database holds the city's spatial layout and the functional relationships within it.

Historical background matters just as much to urban archaeology, of course. From maps, documents and photographs, archaeologists can reconstruct a setting and use it to predict and explain what they find. Take Nieuwe Brug again: the bridge, which linked the east and west banks of the Amstel, was once a playground for traders, craftspeople, sailors, visitors and children. Before Hendrick de Keyser's stock exchange was finished in 1611, it was where ship captains and merchants met. In the 16th century several stone and timber forts were built there as part of the city's northern defenses. So the many ship parts, military weapons and toys pulled out of the water there could be anticipated, and read.

Whether you place objects into the historical picture to fill in blanks, or use history to make sense of objects, the point is the same: what a bridge does gives it a meaning in the terrain, so that it is no longer merely the thing that joins two banks. In Gawronski's words, in this marriage of archaeology and history the city has been understood anew.

Classification

Traditional archaeology sorts objects by material — ceramic with ceramic, iron with iron, bone with bone — and sometimes arranges them by time and place instead. Gawronski's team took another route, because "the relationship between an object and the city is expressed through its function." A city, unlike the countryside, does many more things, and its objects take correspondingly more forms. Sorting by function therefore suits what a city is. The team divided the finds into 11 categories:

1. Nature and the pre-urban environment: 17,906 objects, mostly animal skeletal remains.
2. Buildings: 72,226 objects, including nails, wall bricks, roof tiles, paving stones and window glass.
3. Indoor items: 17,901 objects, most of them to do with portable heating equipment such as braziers and chafing pots. Fittings include keys and locks.
4. Transport: 3,828 objects. Besides ship parts and hulls, one group relates to horse-drawn carriages, including horseshoes and horseshoe nails; others are fragments of bicycles and cars.
5. Craft and industry: 35,161 objects, including sugar pots and funnels used in mass production, waste from leather processing, textile waste and unfinished pottery.
6. Food processing and consumption: 277,628 objects, including food remains (bones above all), earthenware jugs, glass wine bottles, cooking pots, tableware and pipes.
7. Science and technology: 599 objects, including weighing and timekeeping instruments.
8. Weapons: 932 objects — arrowheads, daggers, and early modern weapons including lead shot, firearms and riot smoke bombs.
9. Communication: 4,846 objects — coins (from ancient Roman coins to euros), late medieval and early modern textiles, kosher certification seals, ballpoint pens, book covers and more.
10. Games and recreation: 2,752 objects. Marbles and bones used for throwing games are the commonest toys; others include tin soldiers, fragments of musical instruments and children's tableware.
11. Personal items and clothing: 48,734 objects, mostly leather shoes. Accessories include buttons, belts, combs, jewelry and more.

The digging and the research are done for now, a 15-year marathon brought to a pause. What comes next is a book, a documentary and the running of the website. Ten thousand of the objects will go on show at Rokin metro station, one of the excavation sites; the rest go into the city's artifact store for future exhibitions, teaching and research.

Cover image from: Below the Surface