Archaeologists uncover Iron Age monument in Yorkshire

The 40 foot mound is the only one of its size in Britain with its nearest counterpart being in Germany.

As part of a new project, scientists from the University of Reading have been using radiocarbon techniques to date the mounds of some of the country’s best known mottes - Norman castle or camp sites - and it has thrown up some exceptions.

Results confirmed that this huge mound – 85 metres in diameter and 13 metres high – dates to the middle of the Iron Age with only a handful of parallels on the Continent.

Dr Jim Leary, the archaeologist leading the research, said: “To say that the discovery of an Iron Age monument hiding in plain sight was surprising is an understatement.

Conventional wisdom has suggested that castle mottes were brought to England by the Normans, following the conquest that began in October 1066, exactly 950 years ago.

“Castle mottes exist up and down the country, but their huge size means they are rarely excavated and as a result much of what we previously thought we knew about their date was based on scant documentary evidence and guesswork.

“I excavated Silbury in Wiltshire in 2008, and now to discover the Silbury Hill of the North is wonderful. It adds so much more to our understanding of the people who lived in Britain 500 years before the Romans arrived.”

The project, entitled “Extending Histories: from medieval mottes to prehistoric round mounds”, is being funded by the Leverhulme Trust, and runs for another year.

To make the discovery the team had to drill small boreholes into the base of the mound and recovered materials such as charred seeds or pollen.

They were sent off for lab analysis and from that they were able to date and reconstruct the environment which once surrounded the mound - leading to the revelation Skipsea Castle was already 1,500 years old at the time of the Norman Conquest.