A team of archaeologists, led by a researcher from the University of Bristol, has uncovered the remains of a possible Stonehenge-type prehistoric earthwork monument in a field in Pembrokeshire (Wales).
     Members of the Welsh Rock art Organisation have been investigating the area around the Neolithic burial chamber known as Trellyffaint, dating back at least 6,000 years and in the care of Welsh heritage agency Cadw.
     The site comprises two stone chambers - one of which is relatively intact. Each chamber is set within the remains of an earthen cairn or mound which, due to ploughing regimes over the centuries, have been slowly uncovered. On the capstone that covers the south-eastern chamber are at least 50 engraved cupmarks, that make this site one of only nine Neolithic burial-ritual monuments in Wales with prehistoric rock art.
     Dr George Nash, lead project director from the Department of Archaeology and Anthropology at the University of Bristol and his team have conducted a series of non-intrusive surveys in and around the monument. These included a magnetometry study which covered 80 square metres around the monument and a detailed earthwork survey of the monument itself.
     The geophysical survey uncovered a number of anomalies which are considered to be more than likely buried prehistoric features. Dr Nash said: "To the south and southwest of the stone chamber and appearing to run underneath the southern section of the Trellyffaint mound are two clear circular anomalies. It is regarded that this feature may possibly be a henge (otherwise referred to as a hengiform) measuring around 12 metres in diameter. It is not clear if this feature possesses an accompanying ditch, however, a circular anomaly extends around this feature, again we are unclear of the relationship (if any) with the smaller circle - only excavation will tell."
     Other subsurface features of a probable later prehistoric date occur around the Trellyffaint monument. Dr Nash said: "The next stage of the project will include targeted excavation over recognised anomalies identified from the magnetometry survey. Before we do this, we will be widening the geophysics area and apply resistivity as well further magnetometry over a wider area."
     This fieldwork will take place between April 21 and 23. For details on how to get involved, visit the Welsh Rock Art Organisation's Facebook page.

Edited from University of Bristol PR (24 February 2017)