Thursday, 4 June 2020

Mapping Mountains – Trimble Surveys – Arenig

07.02.20  Foel Goch (SH 953 422), only bwlch surveyed

Venturing to north-west Wales for the weekend I decided that with the weather set fine for the day it was ideal conditions to survey a number of bylchau on the way.  The first of four surveys on the agenda was the bwlch that connects with Foel Goch.

The bwlch of Foel Goch
Foel Goch is situated between Y Bala towards its south and Cerrigydrudion towards its north and its summit was surveyed with the Trimble GeoXH 6000 less than three weeks ago, when along with Aled we traversed its easterly satellite peaks on a gloriously blue skied winter’s day.  That visit was my 22nd to its summit and yet I had hardly paid its bwlch any attention at all, except to find it on a map and estimate its height to deduce the relevant drop value for the hill.  And yet I had passed it on a multitude of occasions whilst driving from Frongoch toward Cerrigydrudion.  During these times I drove past without a cursory glance and yet it was there, beside the road, just a few minutes’ walk from the B4501.  

Foel Goch (SH 953 422)

Many hill baggers, myself included, seemingly walk with proverbial blinkers on, as all that matters is the summit and that all important tick against yet another hill.  The connection between summit and bwlch and the drop therein is important for many classifications of hills, yet, the respective bwlch is seldom visited.

I’ve found since surveying with the Trimble GeoXH 6000 that visiting bylchau has an appeal all to itself.  This rather esoteric aspect of hill walking can take you to seldom visited places amongst the hills where just an occasional farmer or grazing sheep pass by.

Prior to visiting the Foel Goch bwlch I’d looked toward it from a digitised image produced by a Google car on my laptop, and noted a ten figure grid reference produced by interpolation of contours from the OS Maps website.  Parking was not ideal, as it seemed the only available place was on the B road, but as I hoped to be there relatively early in the morning and access through a gate toward the bwlch was on a straight part of the road I was sure this would not be a problem.

Fog clagged any view as I travelled west from Welshpool, and it wasn’t until cresting the top of the B4391 as it wound its way over the Y Berwyn, that conditions cleared with hill summits reaching upward in to blue sky.

I was parked beside the gate on the B4501 at 8.45am and soon had my wellies on, although the ground the other side of the gate as it led down a vehicle track through a grazing field didn’t warrant their protection as the ground was firmly frozen, as was the bog that makes up the bwlch.

By now the morning’s sun had crested the eastern horizon highlighting the small hills to the immediate west with beautiful colour, whilst the frozen ground I was now walking on remained in shade for another 20 minutes or so.

The bwlch stretched out orientated in a north-east to south-west direction, access to it was through another gate.  I walked its periphery looking up its reed grassed interior assessing the lay of land as I did so.  The valley to valley traverse gradually crept upward toward where a small flattened ridge entered the bwlch from the west and complimentarily where a broad grassed bank did likewise from the east.  I also noted this when driving prior to parking and considered the critical position of the bwlch to be near this point.  When in the frozen bog I marched back up it to set the Trimble up further to the north-east for its first of what I decided should be two data sets.  This would at least give a comparison of positions and heights from each point.

As the Trimble gathered its first data set of the day I stood beside a near fence and luxuriated myself in this quiet, seldom visited little spot, where an occasional car and farmers vehicle quickly disappeared off in to the distance on the B road as the sun crept on to the bog bringing morning colour to proceedings.

The first Trimble set-up position at the bwlch of Foel Goch

Closing the Trimble down as its allotted data were gathered and stored, I moved position back through the frozen bog and set the Trimble up for its second data set.  Before activating it to gather data I walked a short distance south-westward in to clumps of reed grass and peered back at the second set-up position; the land was heading uphill from me to it.  Happy with this second set-up position I set the equipment to gather data and stood fifty or so metres from it whilst it quietly beeped away gathering individual datum points.

The second Trimble set-up position at the bwlch of Foel Goch

Once the Trimble was safely packed away I headed on a direct route over two fences back toward the B road before the short walk to my car, it was now 9.30am and the second of the day’s four planned bwlch surveys was only a short drive further westward.  This second bwlch connects with Arenig Fach and is beside the A4212 as it speeds its way past Llyn Tryweryn. 

Survey Result:

Foel Goch

Summit Height:  611.0m (converted to OSGM15, from previous Trimble GeoXH 6000 survey)

Summit Grid Reference:  SH 95379 42292

Bwlch Height:  336.8m (converted to OSGM15)

Bwlch Grid Reference:  SH 91716 43965

Drop:  274.2m

Dominance:  44.88%


For details on the summit survey of this hill

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