Mapping Mountains – Trimble Surveys – Hafod Ithel

 

29.09.20  Hafod Ithel (SN 610 677) 

I’d wanted to visit this hill for many years but until today had never done so.  Although, in part, I wanted to visit its summit, after all this would be another P30 bagged and surveyed, it was its connecting bwlch that was the real interest for me. 

Hafod Ithel is the highest hill in the area of land to the west of the Elenydd and north of Mynydd Preseli and the hills of Pembrokeshire.  Its connecting bwlch is to its east and could be one of two points with a land mass between which has the summit of Banc y Maen Rochorlem (SN 675 691) as the highest.  This latter hill was also on the day’s surveying agenda, but that could wait until after visiting the summit and bwlch of Hafod Ithel. 

For many years the only source available for hill list compilers who wanted to document the drop of Hafod Ithel were Ordnance Survey maps of the day.  These are the 1:50,000 Landranger and 1:25,000 Explorer maps.  Both scales of mapping have contours between 200m – 210m for the two bwlch options for Hafod Ithel, with the 1:25,000 Explorer map giving a 202m spot height positioned at SN 64839 68745 beside a stream and probably not at the critical point for the westerly bwlch option, and a 204m spot height at SN 69535 68656 positioned on a road and in all likelihood not at the critical point for the easterly bwlch option. 

The land mass that takes in Banc y Maen Rochorlem connects with land to its immediate north which then extends westward to the sea and also extends northward toward and following the Afon Ystwyth.  Therefore, the area taking in this land mass has a number of qualifying P30s that could, in effect, have either Hafod Ithel or Carn yr Hyrddod (SN 790 704) as their parent hill. 

Since the days of hill list compilation using just paper maps, there has been a welcome revolution.  This takes in independent surveyors, online mapping and LIDAR.  The latter does not at the moment cover the whole of Wales, however it does cover the easterly of these two bwlch options and I LIDARed this a number of months ago, the result came to 206.210m at SN 69578 68344.  Therefore, the westerly option for the bwlch now required surveying with the Trimble GeoXH 6000. 

Even though the summit of Hafod Ithel and Banc y Maen Rochorlem are covered by LIDAR, I still wanted to survey each with the Trimble and the first on my surveying agenda was Hafod Ithel. 

The ascent of this hill can be an easy one and with a number of hills planned to visit during the day, this was my preferred option.  I parked beside the narrow road that winds its way over the western flank of the hill and followed a greened vehicle track on the moor to the summit. 

The memorial to the Four Poets overlooking my parking place

The summit of Hafod Ithel is crowned by a triangulation pillar and within a few minutes of arriving on top I’d positioned the Trimble aligned with the high point of the hill and waited for the allotted data to be gathered and stored. 

Gathering data at the summit of Hafod Ithel

During data collection I wandered below the high point looking back at the wind turbines near the summit of Hafod Llŷn (SN 625 700), a summit I had just visited and surveyed.  Away to the south grey bulbous cloud hugged near the tops of the Preseli hills, whilst below the watered depths of Llyn Eiddwen glistened. 

Llyn Eiddwen

Once I closed the equipment down and packed it away, it was only a short distance back down the greened track to the car.  Before leaving I visited the memorial stone to the Four Poet’s which sits proudly beside a rib of rock. 

The memorial to the Four Poets

I now navigated the narrow lanes to and beyond the small community of Bronant and parked on a grass verge close to the farm of Pwllpridd.  From here I walked back up the lane to a track that headed down toward the area of the bwlch.  The grey cloud that had hugged the Preseli tops had pushed northward and the forecast continuing sun for the day was now partly obliterated. 

The track wound its way down to an avenue of trees and grazing fields.  Beyond was a mass of reed grass leading to a small conifer plantation.  The reed grass indicated bog and this looked extensive.  However, this route in to the area of the bwlch took me down toward it and bi-passed what looked like horrendous underfoot conditions. 

Arriving at the bwlch I first investigated the area of extensive reed grass and stepped over a drainage ditch come steam to get there.  Prior to visiting I’d looked at the 5m contouring that used to be available on the OS maps website and used this as an indicator for where the critical point lay as the 205m contours almost joined and the ten figure grid reference I had noted indicated the critical point to be back the way I had come. 

Striding back over the murky stream come drainage ditch I zeroed in to the point where the OS Maps 5m contouring gives as the bwlch.  This was close to a gate and a muddied land bridge that crossed a wide drainage ditch. 

The bwlch of Hafod Ithel

I took two data sets, one from where the 5m contouring indicated the critical bwlch was positioned and the next on the same valley to valley fence line and an equal distance on the opposing side of the gate. 

Gathering data at the first of two surveys at the bwlch of Hafod Ithel

During data collection I stood back away from the reed grass and assessed the lay of land at it came from the small conifer plantation toward the gate.  I judged land a few metres from either side of the gate descended north-westward and from its east descended toward the extensive reed grass beside the conifer plantation. 

Gathering data at the second of two surveys at the bwlch of Hafod Ithel

As the Trimble beeped away I sat on the lower part of the gate and waited for the allotted data to be gathered and stored.  This bwlch must only be frequented by an occasional passing farmer and if not for the wide drainage ditch it would no doubt be a quagmired bog. 

Happy with the two Trimble placements that can be compared for the height on the valley to valley traverse I packed the equipment away and retraced my inward route back to the car. 

 

Survey Result: 

 

Hafod Ithel  

Summit Height:  360.4m (converted to OSGM15)

Summit Grid Reference:  SN 61062 67794

Bwlch Height:  204.4m (converted to OSGM15)

Bwlch Grid Reference:  SN 64577 68898

Drop:  156.0m

Dominance:  43.29%

 

For details on the 2^nd visit to Hafod Ithel

 

For further details please consult the Trimble Survey Spreadsheet