The survey party on the summit of Glyder Fawr

The league of Welsh ‘super mountains’ gained a new member today with the news that a survey of a Snowdonia peak revealed its true height to be more than 1,000m

Glyder Fawr, Wales’s fifth highest mountain, has been promoted to the super league following measurements by hill sleuths Graham Jackson, John Barnard and Myrddyn Phillips.

Using high-tech global positioning system equipment, the trio of amateur surveyors spent a day in August getting accurate readings of the height of the mountain, listed by Ordnance Survey as 999m – one metre, or just over 3 feet – short of super-league status.

Their four-hour stint taking more than 500 readings from the group of GPS satellites orbiting 22,000km above the earth nailed Glyder Fawr’s height at 1,000.8m – or 3,283ft in old money.

The elevation of the mountain into the 1,000m league provides a headache for the Gorphwysfa Club, organisers of the annual Welsh 1,000m Peaks Race. The club will now have to decide whether to include the new ‘super mountain’ in its event. The route, from Aber to Snowdon’s summit, would need a significant diversion to the West to include the new 1,000m peak.

The resurvey of Glyder Fawr is the latest for the amateur trio, who now go under the name of G and J Surveys. In June, Tryfan, just 3km (2 miles) from Glyder Fawr, was found to be 917.5m – 2.5m higher than OS maps showed , and allaying fears that the mountain didn’t measure up to the 3,000ft mark.

And in September last year, Sgurr nan Ceannaichean was demoted from its munro status by the trio who found its true height to be 913.43m, a metre or so short of the required elevation.

Graham Jackson explained the men’s views on the expedition. “What are the Welsh ‘super mountains’?” he said. “Of course, heading the list is Snowdon at 1,085m, followed by the adjacent Crib y Ddysgl with a height of 1,065m.”

“Following closely behind and in the north of the Snowdonia national park are Carnedd Llewelyn (1,064m) and finally Carnedd Dafydd (1,044m).

“Does anyone care? Well yes, quite a few people do. For example Wales plays host to many mountain events, one familiar to tourists on the Snowdon Mountain Railway being the Snowdon Race. But, another equally famous is the Welsh 1,000m Peaks Race, where competitors visit all the Welsh 1,000m summits within a given time limit. These international events draw competitors from far and wide.

“One mountain that almost creeps into the list and that is Glyder Fawr at 999m.”

The trio set out to answer the question. “There was only one way to find out if Glyder Fawr is over 1,000m, and that was to go and survey it accurately,” Jackson said. “That is exactly what we did on 16 August.

“The weather was favourable and we set off from Ogwen at about 9.30am following the well maintained footpath leading past the side of Llyn Idwal, steeply up the mountain side to pass under the Devil’s Kitchen, and finally out onto the ridge joining Y Garn to Glyder Fawr.

“Another 300m slog up the scree-covered mountainside took us to the summit rocks of Glyder Fawr.

“This whole area from Glyder Fawr leading to Glyder Fach 1.5km to the East is fascinating to explore, a ‘lunar landscape’ of weird-shaped outcrops set in a sea of shattered rocks.

The survey equipment is set up

“Once the summit position had been identified using optical equipment, the survey-grade GPS antenna was strapped securely to the side of the summit rock and to be level with the top. The GPS receives signals from the satellite constellation orbiting 22,000km above the earth and from these signals it is able to calculate its position. So the instrument was switched on and data recorded for four hours, during which time over 500 individual height readings were collected and this allowed an accurate final result for the height of Glyder Fawr to be calculated.

“The survey was still not finished. In spite of the sophistication of the equipment, the collected GPS data still needs to be processed through dedicated surveying software using correction data available from Ordnance Survey website to give the final accurate result. This we did later that evening.”

The readings showed the mountain as being one of only five south of the Scottish border – England has none – over the 1,000m mark.

Mr Jackson said: “The result has been accepted by Ordnance Survey and the new height will appear on maps in the coming months.

“Of course Glyder Fawr is still the same mountain and in that sense nothing changes, but it does have a new status.

“Perhaps of more importance is the implication of the new height for the fellrunning community. One of the tasks of the Gorphwysfa Club – hence the involvement in the survey of club members Pete and Kate Williams – is the organisation of the Welsh 1,000m Peaks Race.

Glyder Fawr. Photo: Chris March CC-BY-SA-2.0

“This event takes in all the 1,000m mountains in Wales. Now the organisers will have to decide how to embrace Wales’s new super mountain.

“The new height for Glyder Fawr also impacts the UK Prominent Peaks classification devised by UK Metric association members Jim Bloomer and Roddy Urquhart. One of the walking challenges based on the classification is the Prominent Thousanders which is now being revised to include Glyder Fawr as its 134th member.”

The result was announced at noon today at a press conference at Maentwrog in the Vale of Ffestiniog.