Many more dwelling mounds in the Netherlands than previously thought

Long before dikes protected the land, people were already living in wetlands. These fertile landscapes were attractive places to settle, but adaptations were needed to keep dry during floods. This led to the construction of “terps”: artificial dwelling mounds. The oldest Dutch dwelling mounds date back around 2,500 years. In some parts of the country, they continued to be built well into the twentieth century, for example in the IJssel delta, where the youngest date from the 1960s. Terps can contain valuable archaeological information and offer insight into how people adapted to the landscape over time.

Traditionally, the terps in the Wadden Sea region are by far the best known. This is due to the high density of mounds in this area, many of which have also been archaeologically investigated. In the new study, published in Earth-Science Reviews, researchers present the first comprehensive overview of dwelling mounts across the Netherlands. Wageningen University & Research carried out this study in collaboration with the Cultural Heritage Agency of the Netherlands, Het Oversticht and RAAP Archaeological Consultancy.

‘This time we also took a detailed look at other parts of the Netherlands,’ says Roy van Beek, Associate professor Landscape Archaeology at Wageningen University & Research. ‘We brought together all archaeological and historical data on dwelling mounds that had already been identified in different sources. We then combined those with new analyses of digital elevation maps. For the first time, this gave us a complete overview, showing that the Netherlands is incredibly rich in dwelling mounds.’ 

The study shows that dwelling mounds were not only built to protect people from flooding by the sea. Large numbers of terps are also found in other flood-prone areas and river deltas, including those of major rivers such as the Rhine, Meuse and IJssel. They are also common in areas around the former Zuiderzee, including the former islands of Schokland and Marken.

Van Beek explains: ‘In many peatland areas, terps also became necessary because the land was getting increasingly waterlogged as the ground subsided. That process began around a thousand years ago, when large-scale peat reclamation started in the low-lying parts of the Netherlands. Land subsidence is still a major societal issue today.’

The researchers also conclude that most dwelling mounds in these newly investigated areas date from the Middle Ages and later periods. Terps from the Iron Age and Roman period are found almost exclusively in the Wadden Sea region.

Living with water is deeply rooted in Dutch identity. The nearly 9,000 terps uncovered in this study show that, for thousands of years, people in the Netherlands repeatedly and deliberately chose to live in wetlands. These fertile areas offered plenty of space and excellent opportunities for farming. Most dwelling mounds were raised, expanded or modified several times in response to flooding, land subsidence and other changes in the landscape.

‘Most of these terps are still inhabited today,’ says Van Beek. ‘In fact, some new housing projects in flood-prone areas are once again considering building on terps. In that sense, our past, and the stories of adaptation and ingenuity embedded in the landscape beneath our feet, can still inspire us today.’