The story of the Dutch hunebedden took an amazing twist in 1982 when a long-forgotten hunebed was discovered under a mound known as Heveskesklooster on the outskirts of Delfzijl in Groningen Province (red marker on map below). Until it was destroyed in 1586, during the Eighty-Years War, a monastery stood here, hence the name.
The remains of the monastery were undergoing archaeological investigation prior to expansion of an adjacent industrial development when, unexpectedly and totally by accident, a megalithic stone tomb was located in the subsurface of the mound, covered by two metres of clay. When the crypt and the sandy soil below it were examined carefully, the excavators discovered a partly destroyed dolmen with seven sidestones and three capstones. This turned out to be a unique type of hunebed: there was only one endstone, and the entrance, instead of lying on a long side of the dolmen, lay at the opposite end.
The stones were removed and reconstructed in the Delfzijl MuzeeAquairium. It costs €5.50 to enter the building, which offers much more than an aquarium: there are also major exhibits devoted to archaeology, geology, sea-shells, the fishing industry and shipping in addition to the sea aquarium itself—so great value for money. As the only hunebed I have yet to visit, this will be top of my list next time I'm in the Netherlands.
This hunebed is officially named as G5 because sites of three long-vanished hunebedden (G2, G3 and G4) had previously been established by archaeologists.
There is an illustrated account (in Dutch), but with many photographic illustrations, of the excavations at Heveskeskloosterhere.
Excavations at the mound harbouring the remains of the ancient monastery at Heveskesklooster in 1982 provided archaeologists with a major surprise. After peeling away some two metres of clay, followed by a layer of peat, the top of a large boulder was revealed. Jokingly, lead archaeologist Professor H T Waterbolk suggested that it might be a hunebed. But it was soon evident that it was no joke: it was indeed a hitherto unsuspected hunebed, by far the most northerly in the Netherlands.
Hunebedden were typically built in sandy terrain, and Hunebed D5 Heveskesklooster was no exception. The covering layer of clay had arisen because sea-level was at least four metres lower than today during the Neolithic Age, when G5 was constructed: during the millennia since, the site of G5 has been overcome by the sea, allowing deposits of mud to cover it.
Following a year of excavation and study, it was revealed that the dolmen dated from approximately 2500 BCE, about 500 years younger than most hunebeddeden, and that despite being buried, it was by no means in perfect condition. The capstones had been moved from their supports and the sidestones had all been toppled sideways while large chunks broken off some of the stones were strewn around. In addition, the floor of the grave passage had been partly excavated.
Discoveries of just a few flints, axes and amber beads dating from the Funnel Beaker Culture established the age of the hunebed, but the majority of pottery fragments and arrowheads found were considerably younger, estimated as between 2000-1800 BCE. It is theorised that, during this period, the granite stones of G5 may have been utilised as a home/shelter, and may have been vandalised in order to produce millstones for grinding grain.