Jon Lowry, chairman of the Friends of the Thornborough Henges, has received a letter confirming that Tarmac Northern Ltd, which is already quarrying in other areas around the henges, "is shortly to submit a planning application for the Ladybridge Farm area."
The news has confirmed the worst fears of the Friends, who feel the application is the next stage in what they say is the alarming rate of destruction of the 'Stonehenge of the North' – all in the name of extracting gravel for the building industry.
"Enough is enough," said member of the Friends and resident of Nosterfield Dick Lonsdale this week.
"We know that there's likely to be archaeological remains of tremendous importance around the henges, more so than the area immediately at the henges, which was so sacred there was nothing there."
Tarmac are already quarrying in the area to the north of the henges and Nosterfield. The Ladybridge site lies to the east of this quarrying site, while to the west of the henges is a nature reserve. At a meeting last November, Tarmac publicly stated they intended to begin extracting sand and gravel east of the henges in about four years' time.
"The henges and Nosterfield will end up almost surrounded by quarrying," added Mr Lonsdale.
It is not yet known exactly what the application will involve, but the letter, from Edward Bickham, the executive vice-president of the Anglo American mining company, who own Tarmac, states: "Tarmac recognises the importance of preserving the henges and that is why their protection and further enhancement, together with archaeological investigation of nearby land, was incorporated into their draft plans."
But the Friends say quarrying should be halted altogether, as leaving the henges standing alone would not be enough to preserve the archaeological remains in the area.
Another member, Peter Yates, said: "There has been very little found in the henges, everything has been in remote areas such as Chapel Hill.
"They are leaving the henges but destroying everything around them. They will be left but they'll be 30 feet above the surrounding land, which will actually be flooded."
The importance of the 5,000- year-old site at Thornborough has only recently begun to be recognised, with little archaeological fieldwork being undertaken there until the 1990s.
In 1994, Dr Jan Harding, of Newcastle University, who is now a patron of the Friends of Thornborough, established a project to survey the landscape and carry out excavations on the site, which continues to this day.
"Thornborough is a remarkable archaeological landscape, and if the quarrying goes ahead then what is an international resource will be lost," he said this week.
"It needs to be looked after and preserved rather than destroyed, and in that sense, Tarmac's proposal is ludicrous and rather disgraceful."
The Thornborough Henges will be the subject of a half-hour television programme called 'The Stonehenge of the North,' to be screened on BBC2 in October. Filming at the site has been taking place this week for the 'Time Flier' series, which features archaeological digs filmed from a helicopter.
Director Richard Maud said the henges were fantastic, and ranked alongside those at Stonehenge.