Mapping Mountains – Trimble Surveys – Carnedd Llywelyn

31.08.18  Carnedd Llywelyn (SH 683 643, only bwlch surveyed)

The critical bwlch of Carnedd Llywelyn

Having visited Foel Lwyd and Tal y Fan surveying their bylchau and summits I now had an appointment with Janet Ruth Davies, who is a research photographer.  We met outside the Moel Siabod café in Capel Curig and sat in the afternoon sunshine with what looked like the world’s largest scone.

Janet contacted me a few weeks ago and expressed interest in the lines of least resistance, which is the phrase I used to describe how the hill to hill and valley to valley traverse meet and form a critical bwlch.  If weather permitted I suggested we could visit the critical bwlch of Carnedd Llywelyn and Trimble it.

Leaving the café we took two cars toward the small car park adjoined to Gwern Gof Uchaf, a farm that has camping facilities beautifully positioned near the base of Tryfan.  On the way up the A5 cars driving in the opposite direction were flashing their lights, and ahead grey smoke indicated that something was ablaze, it was a car and it looked as if it may explode at any minute as I drove past with flames leaping out of its bonnet.

Thankfully by the time we parked and sorted our gear a fire engine had arrived to douse the flames, but this remained as a near backdrop during the time we were at the bwlch.

A track leaves the outskirts of Gwern Gof Uchaf leading toward Capel Curig, this would have been the old road before the A5 was constructed, it led eastward and we followed it as far as another indistinct track that headed a short distance northward toward the busy road where cars were now stationary as the police and fire brigade dealt with the remnants of the forlorn looking burnt out car.

Heading toward the bwlch

The critical bwlch was only a short distance from where we now were, and I used the Trimble as a hand-held device to zero in to its critical point.  This proved unsurprisingly to be positioned beside a bog.

Having located the position of the critical bwlch which had previously been documented from LIDAR analysis conducted by Aled Williams, I positioned the Trimble atop my rucksack and once the 0.1m accuracy level was attained before data should be logged, I activated the equipment to gather data.  It then stood in place for just over an hour quietly beeping away gathering individual data points, one every second, with 3,650 gathered in all.

Gathering data at the critical bwlch of Carnedd Llywelyn

During this time conversation between Jan and I flowed, and the intensity of the early evening light increased with beautiful colour highlighting the first bronzed tinges of moor grass as summer greenness ebbs in to autumn’s great colour show.

The Trimble set-up position at the critical bwlch of Carnedd Llywelyn

Behind us Tryfan became a silhouetted giant with a backdrop of sky that slowly cascaded in to evening light as slithered cloud accentuated the setting sun.

Jan with the ever present and distinct profile of Tryfan in the background

By now an evening chill had set in, and as Janet and I had exhausted our photographic stock I headed toward the Trimble to close it down.  Its hour long data set is the longest I’ve yet gathered.  It was only a short walk back to our awaiting cars and I waved Jan off before heading down the A5 toward home.

Survey Result:

Carnedd Llywelyn

Summit Height: 1064m (spot height)

Summit Grid Reference:  SH 68364 64375 (hand-held GPS via DoBIH)

Bwlch Height:  313.7m (converted to OSGM15, Trimble GeoXH 6000)

Bwlch Grid Reference:  SH 67558 60463 (Trimble GeoXH 6000)

Drop:  750m (spot height summit and Trimble GeoXH 6000 bwlch)

Dominance:  70.51% (spot height summit and Trimble GeoXH 6000 bwlch)

For further details please consult the Trimble Survey Spreadsheet