POTHOLERS have always said Gaping Gill cavern beneath the Yorkshire Dales was capable of swallowing York Minster.
Now a laser-generated scan has produced the first complete 3D model, which proves the claim is almost true.
The chamber is 446ft long, 151ft wide and 384ft from its floor to the moorland above. In contrast the main tower of York Minster is 197ft high, the transepts are 249ft wide and the building is 518ft long.
Members of York University Cave and Pothole Club, supported by Bradford Pothole Club and Craven Pothole Club, have created a detailed model of the entrance shaft and chamber.
Twelve million points of data were collected by potholers Kevin Dixon, a chartered land surveyor, and Meg Stark to mark the 25th anniversary of York-based laser measurement specialist Measurement Devices Ltd.
It is Britain's biggest known cave chamber and water from Fell Beck that cascades on to the floor of Gaping Gill is Britain's highest unbroken waterfall.
It is seen by scores of visitors to Bradford Pothole Club's annual Whitsun Winch meet, which has been held for half a century, and at a similar event held over the August Bank Holiday by Craven Pothole Club.
A laser systems business development manager at MDL, Kevin Dixon, 43, said: "This has been a very exciting project, which will be of huge interest to potholers and others who wish to study the Gaping Gill cave system.
"The 3D model shows for the first time the rift development in the roof of the main chamber to the west of the main shaft where water is creating a new waterfall."
The information is to be made available to improve maps of the Gaping Gill and Ingleborough Cave System for potholers. It is also being placed on the web at www.mdl.co.uk providing a 3D revolving image for visitors, cavers and students.
Clapham farmer Ian Halliday used his tractor and trailer to take the MDL equipment to Gaping Gill. Bradford Pothole Club allowed use of its winch to access the main chamber and Craven Pothole Club provided a gantry and helped to lower the MDL technology down the entrance shaft.
MDL, based at Northminster Business Park in York, is a global pioneer of laser scanning technology used in the mining and quarrying industries.
The company has other bases in Aberdeen and Houston in Texas.
Gaping Gill Facts
The first attempt to descend Gaping Gill's main shaft was in 1842 when J. Birkbeck was lowered on a rope by farm labourers. He reached a ledge at 190ft still known as Birkbeck's Ledge.
The first successful attempt was made by French caver Edouard Martel who used wood and rope ladders to reach the floor of the chamber in 1895.
Edward Calvert from the Yorkshire Ramblers Club became the first Englishman to stand in the 'Hall of Winds' in 1896 after a wooden beam and bosun's chair was improvised.
Potholers have always been interested in underground watercourses and the Yorkshire Geological Society proved the link between Gaping Gill and Clapham Beck Head Cave after pouring salt into Fell Beck in 1900. It emerged 11 days later.
Visitors who take advantage of the Winch Meets run by Bradford Pothole Club and Craven Pothole Club take about a minute to reach the bottom in a bosun's chair. They are told the descent is free, but it costs 10 to be hauled back.