Mapping Mountains – Trimble Surveys – Y Garn

 

22.06.21  Banc Lletysynod (SN 720 740), Banc Penygwernydd (SN 728 741), Banc (SN 723 729), Grogwynion (SN 720 725) and Pen y Bryn Mawr (SN 705 732, not Trimbled) 

Banc Penygwernydd (SN 728 741)

I’d looked at combining these hills since visiting others in the vicinity after one of last year’s lockdowns was lifted.  Then I’d investigated hills to the north-west and enjoyed the quiet surrounds with narrow country lanes leading between the hills, all of which made a lasting impression.  Today I’d planned a route taking in five P30s and as the last summit was forested, with just four to be Trimbled. 

It was a glorious journey to the hill with mist enclosing the Severn Valley until past Llanidloes, where blue sky crept in to the scene to dominate the western horizon.  I was parked and walking by 7.25am and was soon wandering up a long grassed field aiming for the rising profile of my first hill of the day; Banc Lletysynod. 

As height was gained a slight breeze whisked across the land, for me this was welcome as even this early in the morning warmth was evident.  Except for a distant cloud bank toward the west the skies were an azure blue; a succulent colour that pulled me ever upward. 

One of those unusual sights amongst the Welsh hills

As I rounded the northerly flank of Banc Lletysynod a mass of Range Rovers came in to view.  They were lined up, one after another on both sides of a track that led toward a number of buildings where even more Range Rovers were parked.  I was later told that these were mainly used for parts for Eastern Europe.  They made for one of those unusual sights when amongst the Welsh hills, and one that I find rather heartening as this land is not a manicured landscape, it is one lived in and loved with all its beauty and sometimes unusual elements. 

LIDAR image of Banc Lletysynod (SN 720 740)

Prior to this visit I had examined these hills via LIDAR, producing heights and positions for each summit and bwlch.  Therefore, with accurate height data all I wanted to survey were the summits, leaving bwlch heights and positions to that of LIDAR. 

LIDAR image of Grogwynion (SN 720 725)

The high point of Banc Lletysynod was easily found amongst fresh and greened fern and the Trimble was soon set up gathering its allotted data.  During data collection I peered eastward toward my second hill of the day; Banc Penygwernydd and followed the course of a track up to a fence and then onward beside fir trees to the open hill, it seemed an easy enough route. 

Gathering data at the summit of Banc Lletysynod

Once data were gathered and stored I closed the Trimble down, packed it away and sauntered down the hill aiming for the track which crosses what the map indicates as a drainage channel.  The ascent was in shade and the long grass dew laden.  The higher I got glimmers of early morning sunshine shimmered through near trees, until I reached a large field and the upper part of the hill beyond.  I again, veered toward the northerly flank to then swing south for the final ascent.  The summit of Banc Penygwernydd consists of closely cropped grass and as I set the Trimble up a herd of sheep peered my way from the adjacent field. 

Banc from the summit of Banc Lletysynod

As the Trimble was ebbing down to the 0.1m accuracy level before data should be logged, a quad bike appeared heading my way, I waved across toward it and was soon in conversation with Ivor Hopkins; the farmer from Penygwernydd. 

Ivor Hopkins of Penygwernydd farm

During our conversation I checked the Trimble and then re-positioned it to face east, Ivor said he needed to check on some sheep and would be back in five to ten minutes.  As the quad bike disappeared I pressed ‘Log’ and left the Trimble gathering data until Ivor reappeared.  We chatted for 15 minutes or so about the hills, the Trimble, the names of the hills and my onward route.  He told me where the gates were positioned for my downward progress and said he was now off to cut grass for silage. 

The view north from the summit of Banc Penygwernydd

Gathering data at the summit of Banc Penygwernydd

Descending from the summit of Banc Penygwernydd the greened and inviting profile of my next hill was a dominant feature to my south, this hill’s uppermost enclosed land is named Banc on the Tithe map.  Its summit was about a mile away as the crow flies and I soon connected with the gates that Ivor had mentioned, these brought me back to the minor road that I had travelled on earlier in the morning. 

Banc from the descent of Banc Penygwernydd

I now wandered up another minor road to where a public footpath headed eastward following the course of the ridge crest toward the high point of Banc.  This part of the walk was a delight as the country hereabouts is quiet and all I had for company was birdsong, which invitingly radiated across the land. 

Banc Penygwernydd (SN 728 741)

Banc Lletysynod with Banc Cwmnewydion beyond

By the time I neared the summit of Banc the cloud bank which was evident further to the west had pushed inland and the vivid blue skies of the early morning were suddenly gone.  The summit of Banc consists of an attractive rock outcrop and I had fun aligning the Trimble with the very highest part of rock, whilst balancing its rear on two very small flat stones that enabled it to sit in place for the five minutes of data collection. 

Gathering data at the summit of Banc

The onward route was now south-westward toward Grogwynion which also has the name prefixed with that of Castell on contemporary Ordnance Survey maps, and as this latter name implies it has an ancient hill fort at its summit, the terraces of which were on grand display from this northerly vantage point. 

Grogwynion (SN 720 725)

Below the hill is the farm of Pengrogwynion and I was soon walking through the farm yard with two happily barking farm dogs approaching me.  I’d read reports on the Hill Bagging website of the friendly farmer and even though this was encouraging I would have knocked on the front door anyway, which I soon did.  Wendy answered the door and we were soon in conversation about the hill, farming, my route, the ancient hill fort, the Welsh language, the meaning of being Welsh and where she originated; Liverpool, which was a surprise as she is a fluent Welsh speaker.  Wendy told me that the name of the hill is Grogwynion with the word Castell purely signifying the ancient hill fort as being the castle of the hill of Grogwynion.  She told me about their farm and its original name and where this related to.  We were soon joined by Caredig, who I later met on the walk descending from my last hill of the day.  Before leaving I asked permission to visit the hill and explained I wanted to survey it, this was duly granted.  Wendy told me the best way up and where the original entrance to the settlement was thought to be positioned.  I thanked them for their time and waved by goodbye’s, soon stopping to talk to one of the friendly farm dogs who was lying on a near wall basking in the remnants of sun that pieced the high cloud. 

Caredig and Wendy of Pengrogwynion farm

Wendy had told me to head up beside a water tank next to a rock just off of the narrow gravelled track that leads to the farm.  This gave access to a fenced area that led up to the open hill.  This hill is recommended to visit for its position and profile.  It has a steepening summit cone and gives excellent views north-eastward toward Banc and the continuation of its south-easterly ridge toward Banc Maen Arthur and across the intervening southerly stream valley toward the forested realms of Mynydd Bach. 

Banc from the summit of Grogwynion

After setting the Trimble up to gather its allotted data, I happily sat below the equipment looking out to the continuation of the gravelled track leading from Pengrogwynion as it meandered westward, gaining height toward the narrow minor road that led toward the few houses nestled beside it that constitutes the community of Brynafan. 

Gathering data at the summit of Grogwynion

I could easily have spent longer at the summit of Grogwynion but I still had one summit to visit, but as this was forested the Trimble could now remain in its case as LIDAR gives a height for the summit and dependent upon tree coverage any form of data collected by the Trimble may have a high degree of measurement uncertainty applicable to it. 

The onward route

On my way up the gravelled track I occasionally stopped to look back at Grogwynion; a fine hill nestled amongst many others that are also similar in nature.  The gravelled track soon reached the paved minor road and once past the houses at Brynafan I followed a track leading toward the small reservoir on the right hand side of the road that headed up toward the forestry edge. 

The small reservoir leading to the forested summit of Pen y Bryn Mawr

A foot stile indicates the way in to the forestry, a good path then leads to a forest track.  As I neared the track I heard a car pass, which surprised me, dust was still in the air as I walked directly over the track to the mature trees beyond.  The car was heading toward a house, which I came across on my later descent which is nestled against the north-easterly corner of the forest, with the track being the access road to the house. 

Prior to entering the forest I’d activated the Trimble and taken a compass reading toward the summit.  However, even without the aid of a compass the high point was easy to find.  The summit of this hill is placed in a wide forest ride that has a fallen or felled tree straight over it.  The forest ride is full of tree debris.  I visited both sides of the fallen tree and checked the Trimble co-ordinates against those produced by LIDAR, it was 1 metre out on the easterly and 4 metres out on the northerly,  I was at the summit, which didn’t surprise me as ground descended from this point in all directions. 

The Trimble marks the spot - at the summit of Pen y Bryn Mawr

Reversing my inward route out of the forest I was soon sitting on the foot stile enjoying a late breakfast of a boiled egg.  My route down now followed the periphery of the forest and the continuation of the fence to a track.  On my way I was surprised to find a house nestled in the corner against the conifers.  As I continued away from the forest and down beside a fence a Landrover appeared in the adjacent field, it made a beeline toward me and I waved over toward it.  It stopped beside the fence and I soon scampered up the intervening bank to the fence and smiled when I saw who was getting out of the vehicle, it was Caredig from Pengrogwynion farm. 

He’d come to check on the sheep in the field, this being a part of the land adjoined to his farm.  We talked for 20 minutes or so.  He told me that he has cancer, but still tries to get out to do daily tasks around the farm and is aided my his nephew.  We talked at length about his life and how fulfilling working in the outdoors is, and how the quality of outdoor life was emphasised by the recent and ongoing pandemic and the resulting lockdowns.  I told him of my canal walks during the first lockdown and how the access this gave me to immediate countryside was a great joy during a time that the distance to the hills meant that few were accessible. 

Caredig Thomas of Pengrogwynion farm

Eventually Caredig said he would have to go as he had a few other things that needed doing, but I could have easily stayed there a while longer listening to and talking with him. 

After a short distance farther down the field I turned left on a track which led to the paved minor lane which in time would lead me back to my car.  On the way I listened to birdsong, an ever present and welcome background sound that reverberated around the land.  This was interspersed by the call of a cockerel.  The latter reminded me of walking the middle hills leading to the Marshyangdi valley and the Annapurna circuit and sanctuary trek, where the call of an early morning cockerel was the usual wakening experience.  I spent the next ten minutes of so encountering delightful flash backs to images from Nepal. 

It had been another good day on the hill, when do you ever encounter a bad one, seldom if at all.

 

Survey Result: 

 

Banc Lletysynod

Summit Height:  290.2m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 72010 74093 (Trimble GeoXH 6000) 

Bwlch Height:  246.9m (LIDAR)

Bwlch Grid Reference:  SN 71913 74275 (LIDAR)

Drop:  43.3m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance: 14.92% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

Banc Penygwernydd

Summit Height:  325.95m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 72816 74132 (Trimble GeoXH 6000)   

Bwlch Height:  269.2m (LIDAR)

Bwlch Grid Reference:  SN 72926 74808 & SN 72928 74809 (LIDAR)

Drop:  56.7m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  17.41% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

Banc (significant name change)

Summit Height:  316.3m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 72380 72987 (Trimble GeoXH 6000)   

Bwlch Height:  285.1m (LIDAR)

Bwlch Grid Reference:  SN 72097 73104 (LIDAR)

Drop:  31.2m (Trimble GeoXH 6000 summit and LIDAR bwlch) (Sub-Trichant reclassified to Trichant)

Dominance:  9.87% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

Grogwynion (significant name change)

Summit Height:  288.6m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 72068 72507 (Trimble GeoXH 6000)   

Bwlch Height:  255.8m (LIDAR)

Bwlch Grid Reference:  SN 71921 72581 (LIDAR)

Drop:  32.7m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  11.35% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

Pen y Bryn Mawr

Summit Height:  341.6m (LIDAR)

Summit Grid Reference:  SN 70567 73222 (LIDAR) (summit relocation confirmed)   

Bwlch Height:  222.8m (LIDAR)

Bwlch Grid Reference:  SN 72170 73551 (LIDAR)

Drop:  118.8m (LIDAR)

Dominance:  34.77% (LIDAR)

 

 

For further details please consult the Trimble Survey Spreadsheet