An American writer and researcher’s claim that he has discovered an undocumented ancient monument on Rombalds Moor has been dismissed by a local archaeologist as modern ‘land art’.

Los Angeles-based author, screenwriter and actor, Sean Keir Moriarty, got in touch with English Heritage and Wharfedale Newspapers after spotting what he believes are ancient remains while looking at satellite images via online virtual globe Google Earth.

The site, close to the Twelve Apostles stone circle, contains four concentric stone circles, and is about 20 metres across, says Mr Moriarty.

He was searching for remains of mounds or ringed monuments that might match rock art in the area.

Based on wider research, he believes other large scatterings on Ilkley and Rombalds Moor represents a massive ancient burial or ceremonial site.

He said: “Though the ringed monument in the photo was the only unrecorded one I could locate, I have no doubt that the dozens of areas on the moor, which consist of large scatterings of stones, are the remains of cairns that have either been destroyed or quarried over the millennia.

“In short, Ilkley Moor is, or rather was, a massive burial/ceremonial site.”

But a Bradford Council expert says there is no evidence to support the idea that scatters of surface stones and boulders represent anything other than the natural deposition of stones.

Bradford Council Museums and Galleries Collections Officer, Gavin Edwards, said: "The feature observed by Mr Moriarty is a real one and has been reported on a number of occasions by similarly eagle-eyed observers, but it is known to be a modern one produced in the 1980s and 90s as a type of 'mystical' land art.”

An English Heritage spokesman said it considers all reports of prehistoric archaeology, and asks to see evidence of features being a prehistoric site.