Mystery mound in England turns out to be ancient monument

England, Silbury Hill
England’s prehistoric landscape has a new addition.

Marlborough Mound in Wiltshire has long been a mystery. The flat-topped cone of earth looks like a smaller version of Silbury Hill, pictured here. The bigger mound was finished around 2300 BC at a time when Neolithic farmers were erecting stone circles such as Stonehenge and Avebury. Now archaeologists have taken samples from Marlborough Mound and carbon dated them to 2400 BC.

Carbon dating, which measures decaying carbon isotopes in organic matter, has a slight margin of error that increases the older the sample is. Thus Silbury Hill and Marlborough Mound may have been finished simultaneously, or at least in the same generation. The two mounds are only about 20 miles apart, a day’s walk for a Stone Age farmer or excited archaeologist.

The mound was reused several times. The Romans had a settlement next to it and the Normans built a castle on top of and around it in the late 11th or early 12th century. Early Norman castles were wooden palisades around an artificial mound. In this case their prehistoric predecessors saved them some work. The wooden walls were later replaced with stone ones but the castle has long since vanished. In the 17th century the mound was turned into a garden. The mound stands on the grounds of Marlborough College and is off-limits to visitors. Hopefully that will change now that its true importance is understood.