Tuesday 24 April 2018

Mapping Mountains – Trimble Surveys – Carnedd Wen


16.03.18  Tal Cefn (SH 939 132)

Tal Cefn (SH 939 132)

Having driven past Tal Cefn many times over a great many years I decided it was about time I should visit, and with a weekend at my Brother’s in Nantlle it was the ideal time to visit and survey its summit and bwlch.

The hill overlooks Bwlch y Fedwen which is the critical bwlch of Carnedd Wen and close to the high point of the A 458 road as it makes its way from Y Trallwng (Welshpool) to Dinas Mawddwy, this bwlch consists of a land of tussocks, as does the north-western part of Tal Cefn, ground to avoid at all costs I thought, and with this in mind I planned an ascent from the east following public footpaths to the ruin of Beudy y Bwlch.

It had rained during the night, hours of deluge which had turned potential stream crossings in to hazardous affairs to avoid at all costs, this I only realised after setting off down a steep minor lane leading to the farm of Cae’r-lloi where a quad bike was rattling round a corner of a track heading up in to the hills, my route kept to another track close to the stream forming the Afon Banwy.

The map indicates a Footbridge and Fords that would hopefully help me on my way to the north side of the stream, what I encountered was a thunderous torrent with all hope of crossing being delusional, I backtracked and walked further up the main track as it headed toward Carnedd Wen hoping that a path of sorts would lead on the southern side of the stream toward the hill’s bwlch which was my first surveying objective.

Not wanting to claim too much height on the track only to lose it walking down to the bwlch I spotted what looked like a path heading the way I wanted to go, this soon narrowed but helped as the ground hereabouts comprised the same form of rough tussock as this hill’s north-western slopes, to add insult to injury across the stream was a green track leading toward Beudy y Bwlch, an easy way up the hill if ever I saw one!

I made relatively quick progress through the tussocks, but even rivulet and bog crossings were proving problematic, I’d thankfully worm wellies but when one got firmly stuck in a bog and I instantly reacted by backtracking I almost lost my welly and balance and ended up flat on my back in the bog, the welly sucked itself out as I overbalanced backward, thankfully I remained upright and relatively dry.

Eventually my upward progress brought me to the area of the bwlch, a land full of moor grass, tussock and heather, and a land probably seldom visited unless you are a sheep.  I used the Trimble as a hand-held device to zero in to the ten figure grid reference for the critical bwlch that I had obtained from LIDAR analysis the previous evening and smiled as the Trimble beeped away gathering its allotted five minutes of data, as using LIDAR is so much easier than ten minutes on one’s knees assessing the lay of land from various directions trying to pinpoint where the critical bwlch lies.

LIDAR image of Tal Cefn (SH 939 132)

Gathering data at the bwlch of Tal Cefn

With data stored and the Trimble switched off and packed away I headed up through rough grass to a fence and the comfort of closely cropped grazed grass, a sheer pleasure after the preceding 30 minutes of tussock and bog wandering.

Carnedd Wen rising above the bwlch of Tal Cefn

The Trimble was soon set on top of my rucksack gathering data at the summit leaving me to look down on to the bwlch of Carnedd Wen which I hoped to survey after getting back to my car and driving to the convenient lay-by close to it, this didn’t take place due to a huge and heavy shower that later sped in from the west.

Gathering data at the summit of Tal Cefn

The Trimble set-up position at the summit of Tal Cefn

Once five minutes of data were gathered I headed down toward Beudy y Bwlch and what I thought would be an easy stroll down the green track to the gravelled track on the opposite side of the stream that I had peered toward on my ascent, this would lead me to the main road and a short walk back to my car.  Little did I know that there are two fords, one that I had backtracked from and another that I had not seen and which when I got down to the stream confronted me as a raging torrent, the thought of even attempting a crossing was foolhardy so I backtracked again, this time following the stream back up toward the bwlch of Carnedd Wen, this was debilitating as I was only a few minutes from my car when I had to reverse my direction.

The remains of Beudy y Bwlch

I kept peering down at the stream and it looked horrific, a slender but nevertheless frothing creature running completely out of control, any attempted crossing without a fallen tree to cling on to was completely out of the question.  The fallen tree soon materialised and it was over what looked like a relatively shallow part of the stream, I scrambled down the mud splattered bank and sat beside the fallen tree, the steam thundered past, I put one foot in the water and it gushed over the top of my welly, I slithered backward and back up the bank, only one thing remained; a slow plod up stream toward the bwlch hoping to find an easier crossing, this I found at Pont Dol-y-maen where the stream bubbled under the road and a track led to the main road, I felt thankful to be out of its grasp.

I quickly walked down the road toward my car with a hopeful thumb out for any kind hearted motorist to notice and stop.  As I looked back I noticed a large shower cloud had suddenly appeared heading my way from the west, this soon turned the sky a slate grey and then a car stopped and I got in, thanked the driver profusely and was dropped off at my car just as the first heavy rain drops started to fall.  By the time I jumped in the car and drove the short distance up the road toward the lay-by where I planned on parking to descend and survey the bwlch of Carnedd Wen it was throwing it down, I smiled and continued driving. 


Survey Result:



Summit Height:  352.6m (converted to OSGM15)

Summit Grid Reference:  SH 93936 13273

Bwlch Height:  306.0m (converted to OSGM15)

Bwlch Grid Reference:  SH 93724 12944

Drop:  46.6m

Dominance:  13.22%







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