Wetenschap - 25 juli 2002

Alterra finds 15th century graveyard under dyke

Researchers at Alterra have found a graveyard from the fifteenth or sixteenth century under a dyke at Malburg, near Arnhem along the River IJssel. They did not dig for it, but found it via geo-electronic probing.

The dykes which prevent the Betuwe area from flooding with water from the Rivers Waal, Rhine and IJssel are being strengthened, because of the rising water levels of the rivers due to climate change. Soil scientist John Mulder of Alterra is investigating the history of several dyke compartments around the Betuwe. He is searching for clues as to how the dykes were formed - some of them stem from before the year 1000 - and why. At Malburg he wanted to find out whether the seepage of the dyke was due to artefacts in the dyke.

"We knew there was the farm De Oude Tol near the Rhine at Malburg," Mulder explains. "And that they collected toll money at the site of the farm. We also knew that the castle of Malburg stood somewhere nearby place, and the old church. We dug a ditch parallel to the dyke, under the direction of the Arnhem city archaeologist, and uncovered rubble and some skeletons. Then we asked ourselves: is the rubble from the church, the castle or the tollhouse?"

The digging was not conclusive. So Mulder asked Dr Jan Bervaes to probe the dyke with small electric currents to look for irregularities in the construction. The electric currents are sent in loops through the soil; iron and stone send back a different reflection of the currents. Between four to six metres below the top of the dyke they found small remnants of a graveyard, which they confirmed with soil drilling. "We can't be absolutely certain of the dating," says Mulder, "but we know in the seventeenth century a church in Malburg was flooded.

Martin Woestenburg

Illustration: Map of Malburg in 1586

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