Tuesday 22 September 2015

Mapping Mountains – Trimble Surveys – Mynydd Epynt


18.08.15  Gaer Fach (SO 009 366), Corun Fanolau (SO 015 361) and Cefn Bach (SO 002 372)  

Corun Fanolau (SO 015 361)

The southern ridges of Mynydd Epynt extend for miles and their land that is open to the public gives a tremendous feeling of openness and tranquillity.  However, their northern and central lands are now off limits for most of the year due to the Military Artillery Firing Range.  It was the southern part of the Clepyn Melyn / Drum Ddu ridge that I hoped to visit later in the afternoon.  I say ‘hoped’ as I had been surveying Regional bylchau for most of the day and had just extracted myself from a prolonged period in an 8ft-10ft high Maize crop which was growing in one of the fields that needed surveying.

I parked just off the narrow lane that crests this southern ridge as it makes its way from two miles south of Upper Chapel over and into the Ysgir Fawr valley.  The mid to late afternoon light was beautiful when I set off down the track toward the house of Ffynnon-oer, and the freshness of colour would only get more sublime as the walk progressed.

The narrow lane that crests this southern ridge splits the hills I planned on visiting with the twin 391m map heighted summits of Cefn Bach to its north and the Pedwarau of Gaer Fach and Corun Fanolau to its south. 

As I headed south on the track to the house an old dog barked and wagged its rear end toward me, an indicator that it wanted companionship rather than a show of hostility, I stroked its head and peered into its old eyes, they had a comforting look to them and as I said goodbye I opened a gate and headed on a good path toward the southern and higher flank of Gaer Fach.

The ancient earthen embankment that this hill’s name suggests is part of the hill is now only a semblance of its original construction, but as with most ancient hill forts their positioning is part of their appeal, and Gaer Fach looks out extensively to the higher hills of south Wales.

Today its summit consisted of medium length grass that partly submerged the Trimble as I placed it on what I judged to be the high point of the hill.  To my south-east my next hill; Corun Fanolau had an eloquent shape as its upper section rounded up to its freshly white painted trig pillar.  Further north the distinctive block shaped conifer plantations of the Military Epynt land were on show, it was near to part of this land that I hoped to visit before daylight turned to dusk.

Gathering data at the summit of Gaer Fach

The distinctive summits of the Bannau Brycheiniog

Once the Trimble had gathered its customary five minutes of data I wandered down the south-east flank of Gaer Fach and connected up with the good path that continued from the house of Ffynnon-oer.  This path passed over the critical bwlch of Gaer Fach, and the current Ordnance Survey map spots a place just on the west side of the intervening hedge for their spot height, when I arrived I looked at the land either side of the hedge from the convenience of standing as high as I could on a gate, by doing so I thought land on the eastern side to be higher, and when I started to assess the land from on my knees, land further east away from the intervening hedge seemed higher still.  I nearly set the Trimble up there and then, but closed it down and decided to head up to the summit of Corun Fanolau which enabled me to get a view back down onto the area of this bwlch, this also gave me a further chance to assess the lay of land on my descent from the summit of Corun Fanolau.

Looking down on the connecting bwlch between Gaer Fach (centre of photo) and Corun Fanolau, with the block shaped conifer plantations of the Military Epynt in the background

Corun Fanolau is a rather beautifully shaped hill which has a small quarried section just below its trig.  I found land about three metres from the base of the trig to be the highest and placed the Trimble down and stood back to soak in the view, this takes in most of the south Walian giants and looks out on more Pedwarau as they bathed in late afternoon light.

Gathering data at the summit of Corun Fanolau

Another view of the Bannau Brycheiniog

By now I thought that all of the surveys planned for the day had a chance of being completed, but I still had three more to do on this walk and I then wanted to examine the bwlch of Banc y Celyn (summit at SO 047 464).  This latter bwlch may involve venturing onto Military land and there were another three surveys to be conducted to ascertain where the critical bwlch for this hill was positioned.  Because of this I could not linger.

I quickly packed the Trimble away and left the summit of Corun Fanolau and walked down to the connecting bwlch with Gaer Fach, the point I chose as that of the critical bwlch was where I had also placed the Trimble beforehand, this was a few metres east of the intervening hedge and beside a small flat runnel of stone.

Gathering data from the critical bwlch of Gaer Fach

The summit of Corun Fanolau standing above the bwlch connecting it to Gaer Fach

The southerly top of Cefn Bach

Once the bwlch survey had been completed I walked past the house and the friendly old dog barked its welcome and came for another stroke, by now the occupants had arrived back home as their van was parked outside, I continued down the track past their house and clambered over a fence and into the field where the critical bwlch of Cefn Bach is situated, within a couple of minutes I had assessed the lay of land and chosen the spot for Trimble placement and it was in place collecting its allotted five minutes of data.

Gathering data at the critical bwlch of Cefn Bach

All that remained was a walk up the field to a gate, past my car and through another gate and onto the continuation of the path northward toward the southerly of the two 391m map heighted summits that is given for the high point of Cefn Bach.  Unfortunately I did not have enough time to continue north and survey its second summit as the bwlch of Banc y Celyn still remained to investigate.

As I neared the southerly top I spent a number of minutes assessing the land for its high point as there are two distinct contenders, I eventually decided what one was higher and set the Trimble up.  As it collected data I stood and looked out toward Gaer Fach and a lovely landscape of rolling hill ridges and valley bottoms, a beautiful place to end the day’s summit surveying on.  

Gathering data from the southerly top of Cefn Bach

After the Trimble was packed away I scampered back down the grassed path and within a few minutes I was back at the car sorting my gear out for my last surveys of the day; the bwlch of Banc y Celyn.



Survey Result:



Summit Height:  413.3m (converted to OSGM15)

Summit Grid Reference:  SO 00915 36622

Bwlch Height:  377.4m (LIDAR)

Bwlch Grid Reference:  SO 01225 36448 (LIDAR)

Drop:  35.9m (Trimble summit and LIDAR bwlch)

Dominance:  8.68% (Trimble summit and LIDAR bwlch)





Summit Height:  423.2m (converted to OSGM15)

Summit Grid Reference:  SO 01525 36160

Bwlch Height:  326.7m (converted to OSGM15) (from subsequent Trimble survey)

Bwlch Grid Reference:  SN 99991 39512

Drop:  96.5m

Dominance:  22.81%




Cefn Bach

Summit Height:  389.4m (converted to OSGM15) (390m Sub-Pedwar deletion confirmed) (twin summit status with Cefn Bach positioned at SO 00470 38742 confirmed with 389.392m and 389.391m respectively, with 1mm difference the Trimble is unable to split these tops) 

Summit Grid Reference:  SO 00293 37291

Bwlch Height:  335.0m (converted to OSGM15)

Bwlch Grid Reference:  SO 00287 36949

Drop:  54.4m (prioritised drop for listing purposes)

Dominance:  13.98%




For details on the bwlch survey of Corun Fanolau 

For further details please consult the Trimble survey spreadsheet click {here}




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