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Burial chamber 'could have been used as calendar'

Julia GregoryChannel Islands
News imageStuart Tolcher/BBC A central horizontal stone is inside a stone circle with large stones around it and large pieces of stone forming a roof.Stuart Tolcher/BBC
Martyn Dorey studied the burial chamber for a book on geometry

A mathematician who used geometry to study a prehistoric burial chamber on Guernsey said he thought the monument could also have been used as an ancient calendar.

Martyn Dorey looked at the way light falls in the 6,000-year-old Déhus Dolmen burial chamber at the northern end of Vale Parish for a book he is writing about the use of geometry in finance.

He thought the way shadows were cast on stones at the equinox in March and September could point to it having been used as a calendar.

He modelled the movement of the sun when the dolmen was built and said the carved Guardian of the Tomb image at the site was only lit up briefly for a few days around the equinoxes.

News imageMacey Turner/BBC Martyn Dorey is wearing a blue shirt and he is standing beside the entrance to the burial chamber which is built of large blocks of stone covered by soil with parched grass on the top.Macey Turner/BBC
Martyn Dorey looked at the way the sun hit the stones inside the Déhus Dolmen

Dorey said: "It was probably very important for the people of the time to observe the rhythm of nature."

He said more research was needed.

"We need to make sure these site are protected and celebrated," he said.

"I think much more is to be learnt at these sites."

Dorey said he started to investigate the dolmen for a section on his book about geometry and finance, looking at the early ways people used it.

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