Mapping Mountains – Trimble Surveys – Cilfaesty

14.07.21  Bryn Pant y Drain (SO 178 885) 

Bryn Pant y Drain (SO 178 885)

Bryn Pant y Drain was the second of a planned seven hills to survey during the day.  Prior to visiting, each hill had been analysed with available LIDAR.  For this hill both its summit and bwlch are covered, therefore with accurate bwlch data all I wanted to survey was its summit. 

LIDAR image of Bryn Pant y Drain (SO 178 885)

This hill had stared back at me across the intervening valley from my first hill of the day; Pen y Gelli (SO 180 909).  I contemplated approaching the summit from the north-east on a bridleway following the hill’s main broad ridge, but parking places for this approach were few and far between.  Therefore, I opted to approach the hill from its north driving up a steep narrow lane past an occasion house before the lane crossed a cattle grid in its upper section and then turned to a concrete ramp before an earthen track continued to Upper Highlands farm.  Thankfully there was sufficient space to park where the concrete ramp ended and the earthen track continued. 

It was 8.10am when I locked my car and headed up the hill.  None of these seven hills required long walks, many where easy and if not for surveying each summit, would only require a few minutes to the high point and back to the car.  However, this hill necessitated the longest walk, and even this was relatively short! 

A track is marked on contemporary Ordnance Survey maps heading up this hill from the end of the paved minor lane.  I’d overshot this and continued up the concrete ramp, but as I left the car I followed a stone track leading up the adjacent field, this led through an open gate to a rising field beyond.  The track marked on maps was relatively close and to my right, but as sheep tracks wound their way up toward two mature trees I headed straight up toward them. 

Even by this time of the morning the sun and the steep uphill had brought sweat to my brow.  I stopped occasionally to look back toward my car and over the valley to Pen y Gelli; an inconsequential, quiet rounded green lump, but a good small hill nonetheless. 

Beyond the mature trees I aimed for a gate and once on the other side I rested.  I was now on the continuation of the track marked on the map, which hereabouts swung eastward and eventually joined the bridleway heading down the hill’s north-easterly broad ridge. 

Early morning on Bryn Pant y Drain

I followed the green track for a short distance and then struck out toward the summit which LIDAR indicates is beside a fence.  By the time I arrived at the summit any lingering early morning clag that cloaked some of the higher hills was a distant memory as blue sky now dominated. 

Having assessed the lay of land and compared the ten figure grid reference from the Trimble against that produced by LIDAR I decided to place the Trimble on a fence post and measured a 1.00m offset between its internal antenna and ground at its base.  Once the 0.1m accuracy level before data should be logged was attained I pressed ‘Log’ and stood back and under the equipment. 

Gathering data at the summit of Bryn Pant y Drain

A cooling breeze blew across the hill during data collection, which was welcome.  As allotted data were gathered I checked the map and tried to pinpoint some of the other hills on the day’s surveying and bagging agenda. 

Once allotted data were gathered and stored I closed the equipment down, took a few photographs, packed it away and happily retraced my inward route back to my car.  It had taken 55 minutes to visit and survey the summit of this hill, the next hill of the day; my third, was positioned to the south-west of Kerry and needed at least two tops surveyed for its summit position and as it has no name on contemporary Ordnance Survey maps I also wanted to make place-name enquiries.  The day was progressing nicely, albeit also heating up. 

 

Survey Result: 

 

Bryn Pant y Drain

Summit Height:  383.8m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SO 17865 88597 (Trimble GeoXH 6000)  

Bwlch Height:  327.0m (LIDAR)

Bwlch Grid Reference:  SO 18253 88345 (LIDAR)

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

Dominance:  14.78% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

For further details please consult the Trimble Survey Spreadsheet