Saturday 30 August 2014

Mapping Mountains – Trimble Surveys – UKHillwalking Article


UKHillwalking recently published an article on the Trimble survey of the highest mountain in Y Berwyn; Craig Berwyn.  The article and a link to it on the UKHillwalking website appear below.

Thanks to Alan Dawson for photos and details on Bernard Wright, Peter Collins for details relating to Bernard Wright and Aled Williams for suggesting and having input in to the article.



In Search of the 'Lost' Welsh Mountain
Through painstakingly re-measuring some of Britain's borderline summits, independent surveyors G&J Surveys have been responsible for elevating mere hills to mountain status, and dethroning Munros. G&J's Myrddyn Phillips describes his recent work on the highest point of the Berwyns, a mystery mountain that's never before been given an accurate height, and one particularly close to his heart.
Over 25 years ago a party of 20 were walking on the Berwyn mountains in Mid Wales. The party was being led by Bernard Wright, a former motor oils scientist from Tarvin in Cheshire. As they headed up to the main Berwyn ridge they were confronted by a peak that was absent from their Ordnance Survey maps.
The pointed summit of Craig Berwyn (left) and nearby Cadair Berwyn
Bernard and his friends were standing beside the trig pillar on Cadair Berwyn looking south toward Moel Sych. Both hills nowadays are given the same metric height of 827m. In Bernard's day the map had Moel Sych at 2713ft, and Cadair Berwyn at 2712ft. But something was wrong. The map indicated that these two summits were the highest in the Berwyn, but between the two was another hill, a hill that looked higher, but was not shown as such on any map. 
"Between what the map said were the highest two summits in the Berwyn was another, higher hill"
The group visited the unknown and seemingly 'non-existent' hill and Bernard sat on its highest rock and peered out over the top of Cadair Berwyn and Moel Sych. This hill was definitely higher, but why wasn’t it shown as such on the map? As the friends descended, they chatted about the hill and someone proposed that they should name it Berwyn Wright. A Welsh friend in the party suggested the name Craig Uchaf (...highest), and although an appropriate name it has never caught on.
More recent research I conducted for the ‘Y Pedwarau’ hill list (see UKH article here) revealed that the peak is known to some of the local farmers and shepherds as Craig Berwyn, a name that already appears on the Ordnance Survey map.
Trimble GeoXH 6000 on the key spot

Newspaper clipping from 1988












Back in the Eighties, Bernard reported his find to the Ordnance Survey and was told that the two 827m peaks were the highest points for miles around. Dissatisfied with this answer he persevered and gave detailed co-ordinates for the peak. This prompted the OS to examine their large-scale mapping, on which was found a tiny 830m ring contour that did not appear on the publicly available 1:50,000 and 1:25,000 maps.
The news of Bernard’s ‘new mountain’ hit the headlines, and soon the tiny 830m ring contour appeared on the new OS 1:25,000 Explorer map. However, one thing the Ordnance Survey never did was to give the mountain an accurate absolute height, relegating it to among the few principal Welsh mountains that do not have definitive values for elevation. As the summit is made up of a number of embedded rocks, all jutting out of the ground, the height could well be higher than thought. If an accurate height was given to the mountain, it would also be the culmination of a story that first started over 25 years ago when Bernard Wright and his friends came across a mountain that seemed not to exist.
"The Ordnance Survey never gave the mountain an accurate absolute height"
Here's where I entered the story, armed with a new piece of equipment; the Trimble GeoXH 6000. This fancy bit of kit only weighs 2lb and can achieve accurate height results in no more than five minutes. 
The Trimble GeoXH 6000 is proving to be a great piece of equipment to ‘screen’ hills with, as its precision is +/- 0.15m when compared to our Leica GS15 whose accuracy is +/- 0.05m, but only when we collect upwards of two hours of data. Any hill measured quickly with the Trimble whose height is close to a recognised threshold, such as 2000ft or 3000ft, can then be more slowly surveyed to a higher degree of accuracy with our Leica equipment.
The Trimble GeoXH 6000 gathers its ten minutes of data on the high point of Y Berwyn
However, this particular hill was more than a lump of rock that I wanted to place a bit of surveying equipment on top of. It held an emotional tie for me too, as I had scattered some of my father’s ashes from its highest point. The height of the hill had intrigued me ever since I'd read about Bernard Wright’s new mountain in the late 1980s.
The trip to survey Craig Berwyn proved quite an expedition as I wanted to survey all eleven hills and their respective cols that make up the Maen Gwynedd Horseshoe. This is an extended walk I've done on many occasions but never with the intent to carry out so many surveys. Of course it was the high point of Craig Berwyn that really interested me.
I set out on the 21st June 2014. The surveying expedition would require many hours to complete, but I had settled weather, and the notorious peat paths of the higher Berwyn were dry. As the highest rocks of the Berwyn were approached a slight breeze picked up, but not enough to worry me as I placed the Trimble on the very highest point of the mountain range, the same spot that Bernard Wright had peered from all those years ago. The view from the summit took in all the higher Snowdonia peaks to the west as well as the lower hills towards the English border. In all the surveying trip took over 12½ hours to complete. 
Ten minutes of summit data were collected by the Trimble GeoXH 6000 and later post processed, giving a result of 831.98m +/- 0.15m.  So over 25 years since Bernard Wright first discovered the mountain its true height is now known, and at 832m it seems that the little 830m ring contour on OS maps is hiding quite a substantial rock under it!

Further details of this survey and others can be found on Myrddyn’s blog:


Please click {here} to see the original article published on the UKHillwalking website

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