A senior investigator with Historic England will visit Worlebury Hill Fort next month.
Mark Bowden and his team will produce an analytic survey of the monument, which will list its important features and relate them with their function.
The group will examine the valla outside the scheduled area, which contains three ancient walls and ditches which have a different alignment from the Iron Age fort, which could mean there is an older but smaller Bronze Age site adjacent to it.
MORE: Public consultation over Hill Fort.
Alessandra Perrone, Historic England’s at risk officer, visited the Hill Fort in October two years after she placed it on Historic England’s at risk register.
She asked the volunteers to clear scrub from part of the valla, which will help the team survey these extra features in December.
North Somerset Council gave formal permission for the volunteers to work outside the scheduled area.
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