Saturday, 17 October 2015

Mapping Mountains – Trimble Surveys – Elenydd


25.09.15  Garn Wen (SN 845 459) and Pen Twyn (SN 857 463)  

Garn Wen (SN 845 459)

As I travelled south the early morning chill and clear skies foretold a good day on the hill.  I planned on doing two small walks near to Llanwrtyd, however as I neared the smallest town in Britain a large grey cloud bank emerged over the western part of the Elenydd.  This quickly pushed east and by the time I’d parked in the yard of Ty’n-y-maes farm there were spots of rain falling.

I’d been on one of the two hills I planned on visiting during my first walk once before, in July 2000, and did on that day what I hoped to do today, get permission to park at the farm and approach the hills from the south-west on a good track that leads up beside the Nant y Cae.

As I drove into the farm yard Tyssul Davies was already busy at work, once I’d introduced myself and mentioned my previous visit we chatted for ten minutes about the names of the hills and the route up to their summits.  By now the rain was falling so I thanked Tyssul and wondered if I should sit out the wet weather.  Not wanting to linger I grabbed my brolly and set off up the track.

The gravelled track soon became a green lane and pushed its way up the cwm, my brolly was up and sheltered me, my rucksack and my camera gear, an umbrella can be a great addition to hill walking kit for the lower hills.  Ahead the sky was deep grey and did not look inviting.

The green track to the hills with the deep uninviting grey cloud ahead

I left the green track before its end and jumped over the narrow stream and clambered over a fence and followed a vehicle track on the moor as it gained height adjacent to a contouring fence.  In time this led through an open gate on to the upper part of Garn Wen.

I remember this hill being rather wild from my previous visit and it didn’t disappoint today, the whole summit area is one of tussock grass, heather and bog, all leading up to its ancient cairn that has been re-fashioned into a wind shelter with its trig pillar sitting inside.  As I gained height the large ancient cairn came into view across the moor, between me and it was an unsavoury bog which proved fun to cross.

The ancient cairn at the summit of Garn Wen

Once at the summit I considered placing the Trimble just to the south-west of the cairn and trig, but I then examined inside the wind shelter and found stable ground within it which was higher than the ground just to the south-west.  This high ground could of course be made of rocks from the ancient cairn but I did not want to excavate something from antiquity so I placed the Trimble on top of my rucksack, positioned three rocks at its base, which I re-positioned afterwards, to stabilise it and once the accuracy level was attained I pressed ‘Log’.

Gathering data at the summit of Garn Wen

As I waited for the five minutes of data to be collected the first burst of sunshine shone out of a brightening sky.  Packing the equipment away I followed a vehicle track down toward the bog which proved an easier crossing that my alternative ascent route.  I then roughly re-traced my route back down to the fence and the narrow stream.

Following the vehicle track on the moor toward the second hill of the day

I had no immediate intention of gathering data from the connecting bwlch to Pen Twyn as the map indicated that it was immersed in a conifer plantation, but there was a gap between a small section of mature trees and a larger section of saplings, so I thought I’d investigate.  I stumbled my way down to this land from the open hillside, found a tree stump and positioned my rucksack on it with the Trimble placed on top and gathered another five minutes of data.

Gathering data at the bwlch of Pen Twyn

By now the deep grey cloud had been swept away and sunshine pre-dominated as I followed the fence beside the large conifer plantation toward the summit of Pen Twyn.  This is the hill that Anton Ciritis completed the Pedwarau on, on 9th September 2014.  The summit area has a neat cairn positioned on it and I placed the Trimble on top of my rucksack approximately 1 metre from it on what I judged to be the highest part of the hill.

Gathering data at the summit of Pen Twyn

Once the allotted five minutes of data were gathered I packed the equipment away and descended the southerly part of the hill, this proved steep in places and gave views south toward the shapely profile of a 396m map heighted hill which is listed as a Sub-Pedwar with c 113m of drop.

All in a line

The shapely profile of Pt. 396m (SN 847 436)

The southerly profile of Pen Twyn

This southerly route down the hill led to a vehicle track over a field which then accessed a gate and the track back to Ty’n-y-maes.  As I arrived in the farm yard Tyssul was in conversation with three people, I stopped and chatted and showed him on the map where the next two hills on my planned second walk were situated, and he kindly suggested what farm I should park at.


Survey Result:


Garn Wen

Summit Height:  511.6m (converted to OSGM15)

Summit Grid Reference:  SN 84511 45973

Drop:  75m

Dominance:  14.66%




Summit Height:  476.6m (converted to OSGM15)

Summit Grid Reference:  SN 85798 46301

Bwlch Height:  431.5m (converted to OSGM15)

Bwlch Grid Reference:  SN 85241 46419

Drop:  45.1m

Dominance:  9.45%



For further details please consult the Trimble survey spreadsheet click {here}



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