Mapping Mountains – Trimble Surveys – Gwaun Ceste

 

24.06.22  Twyn y Garth (SO 107 437) 

LIDAR image of Twyn y Garth (SO 107 437)

Twyn y Garth had passed me by on many a journey as I headed south toward other hills on the A470 road.  Although I had visited its higher neighbours to the north and east, it was its inclusion in The Huws – 100 Great Welsh Hills under 2,000ft that prompted my suggestion to visit.  However, it also tied in nicely with what Aled and I planned to do with the majority of the day.  The morning of which was spent at the Crucywel (Crickhowell) archive examining historical maps and documents relating to the Black Mountains hill range.  With the archive closing at 12.30pm it gave us time to visit a hill or two in the afternoon as we headed back north.

The forecast was not conducive to hill bagging with heavy localised showers predicted and the possibility of thunder and lightning edging its way into Wales in the afternoon.  By the time we had dealt with all necessary documents at the archive centre the early morning murk that had nestled forlornly on many hill tops during our journey south, had lifted, but the grey gloom still predominated above.

The first hill we headed toward was Mynydd Llan-gors (SO 159267), as I had visited this hill on three previous occasions I waited in the car as Aled headed up, 55 minutes later and he was back at the car.  During his ascent a scud of rain passed over the land for ten minutes or so, nothing to really dampen proceedings but I wondered if this was a foretaste of what may materialise later in the afternoon.

On the drive north from Mynydd Llan-gors there was another scud of rain that again petered out after ten minutes, but the sky still remained a foreboding deep grey, with it always threatening a downpour.

There are few opportunities to park on the minor lane that heads to the north of Twyn y Garth.  We called at the two houses at the end of the lane’s paved section to ask permission to park.  No one was in, so having left a note on the dashboard explaining where we had gone, I pulled my car off the main steep gravelled track leading to each house and away we went through a gate and on to the hill.

The summit cone of Twyn y Garth rises steeply from the direction we approached, at this time of year its upper slopes were festooned in greened fern.  A conveniently placed path contoured its way beside a boundary fence heading westward, we followed this until the steep slopes above gave way to grass, and heading up at this point saved a thrash through high bracken. 

The steep slopes leading up Twyn y Garth

As we gained height the conditions became muggy, the sky to the south always threatened rain, but thankfully whilst on the hill this did not materialise.  Aled soon pulled ahead and as he disappeared over the ridge crest leading toward the high point of the hill I slowly followed.  The summit area of Twyn y Garth is encircled by the remains of an impressive ancient hill fort and I followed one of its embankments around its southern side and met Aled close to the top, he was standing beside the First World War German Field Gun that is positioned just below the high point of the hill.  This was placed on the hill in memory of the brother of Mrs Lionel Trafford and other local men who died in the 1^st World War.  I have not encountered such an object as this on any other Welsh hill.  There are more recent relics of warfare scattered on parts of Mynydd Epynt, but the placing of this German Howitzer is probably unique as a testament to lives lost during conflict. 

The 1st World War field gun positioned just below the summit of Twyn y Garth

The plaque on the field gun

Aled beside the German Howitzer

As I approached the summit, Aled joined me on top and we debated where the high point was positioned as two contenders vied for this accolade; one on the outer embankment and one on the inner embankment, with a steep ditch between.  LIDAR indicates ground on the inner embankment as higher and this is where the Trimble was set up. 

Gathering data at the summit of Twyn y Garth

As the Trimble gathered its individual datum points we stood below the equipment so as not to disturb satellite reception.  After five minutes data collection I turned the equipment off, took a few photographs and packed it away.

We quickly reversed our inward route as the sky was still threatening heavy rain.  When we arrived back at the car I checked my watch, the walk and survey had taken just 30 minutes and a few of these were spent debating where the summit was positioned! 

 

Survey Result: 

 

Twyn y Garth

Summit Height:  324.3m (LIDAR)

Summit Grid Reference:  SO 10733 43731 (LIDAR)  

Bwlch Height:  270.7m (LIDAR)

Bwlch Grid Reference:  SO 10654 43937 (LIDAR)

Drop:  53.6m (LIDAR)

Dominance:  16.53% (LIDAR)

 

 

For further details please consult the Trimble Survey Spreadsheet