Mapping Mountains – Trimble Surveys – Mynydd Epynt

13.06.17  Erw Penlan (SO 045 495) and Garth (SO 053 506)

Garth (SO 053 506)

Having visited Mynydd y Drum, Teisen Priodas and the Nant Helen Opencast Mine, followed by a survey of the critical bwlch for Fan Brycheiniog I wanted to continue testing my wonky right knee with a small walk on the way home, and to do this the delights of Garth was perfect.

For such a small heighted hill, Garth occupies commanding land above Llanfair-ym-Muallt (Builth Wells) and looks out over the Afon Gwy (River Wye) as it swings southward from an easterly course.  It is a hill that I wanted to visit for many years and with the weather improving and blue skies edging past the early morning grey, it was a perfect time to do so, as long as my knee withstood a few extra miles.

A series of narrow country lanes ascend the land to the south of Llanfair-ym-Muallt (Builth Wells) and adequate parking can be problematic, however I found a suitable place close to where a public footpath heads toward Newry Farm.  Within a few minutes of setting off a voice called out and told me that I was on the wrong course, I waved and double backed and chatted with an elderly woman from the farm who kindly directed me through two gates, unfastening the bailer twine wrapped around each.  She described the route that I should take; up the field, through a gate and to the top of the wood, adding that I should be careful as there may be a bull in the field.  Waving my thanks I went through the gate in to the wood, I can’t imagine many people come this way as there was little sign of a path through the wood, but it brought me out to the field where the critical bwlch of my first hill of the walk lay.

Studying the map prior to the walk I noticed that I could confirm the status of a Sub-Twmpau on my way toward Garth, this sub hill is named Coetgae Fawr on the map, this when translated into English can mean the large enclosure.  The following day when back home I studied the Tithe map and found the enclosed land where the Trimble had been placed was named Erw Penlan, which can be translated as top of the enclosed acre, and as this is where the map spot height and the Trimble was placed it is the name of this enclosed land that this hill is being listed by.

By the time I arrived at the bwlch of Garth the heat of late afternoon was beating down, I placed the Trimble on top of my rucksack to give it elevation above its immediate surrounds, measured an offset of 0.41m between its internal antenna and the ground at the base of the rucksack and waited until the 0.1m accuracy level was attained before data should be logged, once attained I quickly pressed ‘Log’ and retired to the shade under near trees.

Gathering data at the critical bwlch of Garth

Garth from its critical bwlch

The summit was only a short distance above and over fields and a fence, I was too hot and sweaty and my eyesight not good enough to make sense of a small spot height on the Ordnance Survey 1:25,000 Explorer map that I was carrying, so I headed up and judged the lay of land as I did so, I judged the high point to be over the fence at the top in the field to the immediate south of the enclosed wooded part of the hill.

After setting the Trimble up I waited for an inordinate amount of time until the 0.1m accuracy level was attained, but eventually this figure appeared on the screen and after pressing ‘Log’ the equipment beeped away gathering its individual datum points.

Gathering data at the summit of Erw Penlan

As I waited for the allotted five minutes of data to be stored I spotted two gates lower down adjacent fields that gave access toward the next bwlch.  Once the Trimble was switched off and packed away I sauntered down through the warmth of the day to a T-junction of narrow lanes and tracks, this is where the critical bwlch of Erw Penlan is placed.  I had difficulty judging where this bwlch lay, partly because my head was now frazzled by the heat but also because the camber on the lane meant that there seemed to be a slight up and down associated with both the valley to valley direction and the hill to hill direction.  Eventually I chose the spot and placed the Trimble to gather its all-important data.

The view of Garth on the descent toward the critical bwlch of Erw Penlan

Gathering data at the critical bwlch of Erw Penlan

All that remained was the ascent of Garth, which proved a slow plod up a delightful path with ever expanding views.  Nearing the top a young couple overtook me; they remained on top sitting in the sun as I set the Trimble up for it to gather its last data set of the day.

The view of Erw Penlan (SO 045 495) on the ascent of Garth

I’d consulted the Hill Bagging website prior to this walk and the summit of Garth is given as ground within one metre of the base of its trig pillar.  I spent a number of minutes judging the land at the summit and asked the young couple their view, the three of us all thought that land approximately seven metres from the base of the trig was the highest, after setting the Trimble up I stood back and admired the view, which is stunning.

Gathering data at the summit of Garth

The view south toward Mynyddoedd Duon

The Trimble set-up position at the summit of Garth

After five minutes of data were gathered I switched the equipment off, packed it away, said my goodbyes to the couple and very slowly plodded down the path back to the country lane which took me back to my car.  On my way down I met another four people heading up, all out enjoying the early evening sunshine.  It took quite some time to get back to my car as my knee felt as if it wasn’t joined to my leg and each step gave a twinging sensation as pulled cartilage grinded away at the rear of my right knee.  Although my knee ached it had been another good day on the hill with lots of interesting data results to process.

LIDAR bwlch image for Garth

Postcript:  Since the Trimble GeoXH 6000 survey of Garth, LIDAR has become available and this has resulted in the bwlch moving by 4 metres in position, although the height remains the same. 

Survey Result:

Erw Penlan (significant name change)

Summit Height:  212.1m (converted to OSGM15) 

 

Summit Grid Reference:  SO 04597 49535

Bwlch Height:  191.1m (converted to OSGM15)

Bwlch Grid Reference:  SO 04990 49608

Drop:  20.9m (200m Sub-Twmpau addition confirmed)

Dominance:  9.87%

Garth 

Summit Height:  280.3m (converted to OSGM15)  

Summit Grid Reference:  SO 05316 50618

Bwlch Height:  170.9m (LIDAR)

Bwlch Grid Reference:  SO 04373 49739 (LIDAR)

Drop:  109.4m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  39.04% (Trimble GeoXH 6000 summit and LIDAR bwlch)

For further details please consult the Trimble Survey Spreadsheet