Tuesday, 9 July 2019

Mapping Mountains – Trimble Surveys – Cymoedd Gwent


19.04.19  Yr Allt (SO 056 162), Bryniau Gleision (SO 084 161), Cefn yr Ystrad (SO 086 137), Cwar yr Ystrad (SO 082 140), Cwar yr Ystrad (SO 084 142) and Tor y Foel (SO 114 194)  

Tor y Foel (SO 114 194)

Cefn yr Ystrad stands adrift of the higher Welsh mountains with the peaks of Bannau Brycheiniog to its north and the Cymoedd Gwent hills adjoined to its south.  I hadn’t been to its summit for 14 years, but with two relatively recent new Uchafion hills in the quarry to its west found from LIDAR analysis conducted by Aled, it was time for me to re-visit.

I met Aled in Caersws, stopping on the bridge entering the village to admire and take a few photos as the last lingering mist of the morning slowly gave way to the warming sun.  We were parked and walking by 8.50am above the Tal-y-bont Reservoir following vehicle tracks rising steeply on the hillside heading forever upward toward the summit of our first hill of the day; Yr Allt.

Early morning mist

The ten figure grid reference produced by LIDAR zeroed the Trimble in to the hill’s high point and as the first of 15 data sets for the day were gathered, I stood close to the trig pillar with Aled as a hazed view silhouetted the higher hills to the north.

Gathering data at the summit of Yr Allt

Thankfully underfoot conditions were relatively dry and a good path soon led us down to its connecting bwlch and again LIDAR led me to its critical point, and a few moments later the Trimble was set up atop my rucksack and the allotted data were gathered and stored.

Gathering data at the critical bwlch of Yr Allt

Away to our south the quarried face of Cefn yr Ystrad was giving a little detail against the morning haze and one of the gashes separating the quarried cliff could be picked out.  In a few hours we would be there wandering around the quarry visiting the two new Uchaf hills.

Aled suggested a cunning plan for our descent, and this meant that on our inward route toward Cefn yr Ystrad we could visit the summit of Bryniau Gleision, surveying it now, rather than on our outward walk.  The summit consists of a grassed knoll overlooking an attractive small crag and as Aled investigated the flowers growing on the steep ground I set the Trimble on the high point and stood back during data collection and peered toward Cefn yr Ystrad which still looked quite a distance away.

As Aled wanted to visit Trefil Du; he set off as the Trimble gathered summit data with us arranging to meet beside the trig pillar on top of Cefn yr Ystrad.  Once five minutes of data were gathered I switched the equipment off, packed it away and headed down the broad southerly ridge of Bryniau Gleision toward its connecting bwlch, which proved to be beside a water course in a wild spot that if not for the occasional passing mountain surveyor I doubt that anyone ever visits.

Gathering data at the summit of Bryniau Gleision

Gathering data at the critical bwlch of Bryniau Gleision

After gathering bwlch data I slowly made my way over the moor toward a path that led up to the quarry track leading to the higher ground of Cefn yr Ystrad.  By now the day was heating up with blue cloudless skies overhead.  Following the main quarry track I soon arrived at where a corner of an adjacent barb wired fence gives access on to open hillside and proceeded to slowly plod uphill to one of the large ancient cairns that adorn the summit area of this hill.  I proceeded to gather data from two positions; one at the high point of a large embedded rock on the eastern side of the ancient cairn and the other on its western side on the highest bit of grass at the base of the cairn.  As I was setting the Trimble up for the second of these surveys Aled appeared having made his way back from the easterly outlier of Trefil Du.

The Cwar yr Ystrad quarry from the ascent of Cefn yr Ystrad

The first of two surveys beside the ancient cairn on Cefn yr Ystrad

The second of two surveys beside the ancient cairn on Cefn yr Ystrad

Once the Trimble was packed away we headed to the trig pillar for a sit down as another data set was gathered on the highest rock near the base of the pillar.  Once Aled’s pick and mix was devoured we set off on a compass bearing heading westward to where access can be gained in to the Cwar yr Ystrad quarry and the first of a series of surveys that would occupy us for the next two hours.

Gathering data at the summit of Cefn yr Ystrad

The quarry is hidden from view from the summit of Cefn yr Ystrad but it straddles its western and northern upper face with a flat quarry floor and attractive, steep cliffs rising from it with the two Uchaf summits being the respective high points separated by a gash through the cliff.

The next survey was at the point where we accessed the quarry and is the bwlch for the lower of the two Cwar yr Ystrad summits, from here the route toward the first summit was easy, with a dramatic view immediately to our east down the quarried cliffs.  On our way to the summit we decided to gather another data set at where a gash through the cliff appears, and this can be compared for bwlch position against the previous survey.

The first of the Cwar yr Ystrad bwlch surveys

The second of the Cwar yr Ystrad bwlch surveys

The summit of the first of the two Cwar yr Ystrad hills has a large rock on it and soon the Trimble was aligned to its high point gathering its all-important data.  Once data were safely stored we back-tracked to gain a track leading down to the flat quarry floor where the next bwlch was positioned.

Aled at the summit of Cwar yr Ystrad (SO 082 140)

Gathering data at the first of the two Cwar yr Ystrad summits (SO 082 140)

The ten figure grid reference produced by LIDAR led us to the critical point of the bwlch which had the sheer cliff face of our next hill as backdrop.  As data were gathered I sat with Aled whilst a refreshing breeze sauntered through the quarry, but the early afternoon heat was increasing and there was a long walk ahead of us out of the quarry that would soon have to be tackled.

The third of the Cwar yr Ystrad bwlch surveys

A conveniently placed rubbled rocky rib cascaded down from the upper cliff giving us easy access from the quarry floor on to higher ground.  The walk around the top of the cliff was superb and led to two points which were both Trimbled with the furthest north our chosen candidate for this hill’s high point.  Both were dramatically placed on the very edge of the drop down to the quarry floor.

Gathering data at the second of the two Cwar yr Ystrad summits (SO 084 142)

All that remained was the long, hot walk out.  However, Aled’s cunning plan hatched earlier in the morning saw us head in different directions once we had left the quarry and joined one of the paths leading toward the eastern lower part of Bryniau Gleision, as I headed back on our inward route, whilst Aled continued on the path that soon became a good track heading toward the Pedwar of Bryn Melyn and the higher Tor y Foel, he also took the Trimble to survey the latter’s connecting bwlch and summit.

My route out was torturous as it involved cresting three small ridges to get back on to the main path we had followed earlier in the day.  Each little bit of uphill made me suffer as the heat increased.  However, the surroundings were to be savoured as my only companions were wild horses grazing on the moor.

I contemplated losing height and entering the forest to my north where a track led back toward my car, but thought better of it and resigned myself to regaining the summit of Yr Allt.  This proved a slow process with a few stops to regain my breath on the way.  When I reached the trig pillar I lay in the sun and munched on a banana, and 30 minutes later I was back at my car extremely happy to get my boots off and sit and try and recover having been on the hill for about nine hours.

I now needed to pick Aled up who was waiting for me at the end of the paved road at the bwlch between Bryn Melyn and Tor y Foel.  It was a 25 minute drive to get there with miles of narrow roads to negotiate.  It had been another good day on the hill with two new Uchaf hills for me and eight hills in all for Aled.        



Survey Result:



 
Summit Height:  564.7m (converted to OSGM15)

Summit Grid Reference:  SO 05633 16201

Bwlch Height:  493.5m (converted to OSGM15)

Bwlch Grid Reference:  SO 07090 15748

Drop:  71.2m

Dominance:  12.61%





Bryniau Gleision

Summit Height:  538.1m (converted to OSGM15)

Summit Grid Reference:  SO 08449 16121

Bwlch Height:  502.4m (converted to OSGM15)

Bwlch Grid Reference:  SO 08260 15254

Drop:  35.8m

Dominance:  6.65%





Cefn yr Ystrad

Summit Height:  617.4m (converted to OSGM15)

Summit Grid Reference:  SO 08696 13729 (summit relocation confirmed)

Bwlch Height:  439.9m (converted to OSGM15) (from previous Trimble survey)

Bwlch Grid Reference:  SO 05261 17241 (from previous Trimble survey)

Drop:  177.5m

Dominance:  28.75%





Cwar yr Ystrad

Summit Height:  572.7m (converted to OSGM15)

Summit Grid Reference:  SO 08211 14086

Bwlch Height:  555.2m (converted to OSGM15)

Bwlch Grid Reference:  SO 07950 13645

Drop:  17.5m (Uchaf status confirmed)  

Dominance:  3.06%





Cwar yr Ystrad

Summit Height:  579.3m (converted to OSGM15)

Summit Grid Reference:  SO 08445 14278

Bwlch Height:  558.8m (converted to OSGM15)

Bwlch Grid Reference:  SO 08376 14189

Drop:  20.5m (500m Sub-Twmpau status confirmed)

Dominance:  3.54%





Tor y Foel

Summit Height:  551.0m (converted to OSGM15)

Summit Grid Reference:  SO 11457 19493

Bwlch Height:  394.0m (LIDAR)

Bwlch Grid Reference:  SO 10218 17757 (LIDAR)

Drop:  157.0m (Trimble summit and LIDAR bwlch)

Dominance:  28.49% (Trimble summit and LIDAR bwlch)










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