Sunday, 15 October 2017

Mapping Mountains – Trimble Surveys – Y Berwyn



02.09.17  Garnedd Wen (SJ 131 311) and Mynydd Mawr (SJ 133 286)

Mynydd Mawr (SJ 133 286)

Having been away from the hills for two months I wanted a fairly easy walk to ease my way back on to them and combining Garnedd Wen with Mynydd Mawr was a perfect way for my right knee to recuperate without being tested too much.

A narrow road heads eastward from Maen Gwynedd toward Llanarmon Dyffryn Ceiriog and the grass verge close to the connecting bwlch between the two hills proved an ideal parking spot.

I set off at 8.30am just as the early chilled morning gave way to the first warmth of the day.  It felt good to be back on the hills amongst quiet surrounds with a radiant blue sky above and just a breath of breeze adding to the beauty of patch worked green fields which were dotted in white sheep smothering the land.

A vehicle track on the hillside soon gave way to a closely cropped grassy field which led up toward the summit of my first of two hills of the day; Garnedd Wen, which is listed as a 400m Sub-Pedwar.  Skirting the summit I headed down toward the hill’s critical bwlch and aimed for a gate giving access on to moorland and a track heading toward a fence that crosses the bwlch in a hill to hill direction.  After assessing the lay of land from a number of directions I decided that one of the fence posts was as good as any to be declared the position of this hill’s critical bwlch and set the Trimble up accordingly.

As the Trimble gathered its customary five minutes of data I stood back and admired the main Berwyn ridge which from this viewpoint butted against the lay of land as it blocks the course of west to east ridges, immediately in front was the continuation of steep land toward the ridge leading to Mynydd Tarw, however tempting this was I realised that a gentle walk was required to accustom my knee to the rigours of hill walking and over ambitious plans may prove detrimental in the long term.

The main Berwyn ridge

Gathering data at the critical bwlch of Garnedd Wen

Y Garn (SJ 080 272)

With the Trimble packed away I headed to the summit of Garnedd Wen where the remains of quartz rocks were jumbled together overlooking the greened and pleasing slopes of Mynydd Mawr, a marvellous scene to look at for someone who has been devoid of mountain views for the last two months.

Mynydd Mawr from the quarzt rocks atop Garnedd Wen

I again positioned the Trimble on a fence post having judged the land at its base to be the summit of the hill, this time improvising and laying my Goretex coat on the post as a part of the barb wired fence had been hammered in to its top, by placing the Trimble on top of my coat it protected its underside and elevated it above its immediate surrounds, once the offset was measured with a steel tape it bleeped away gathering its 300 allocated datum points.

The gentle north-western slopes of Mynydd Mawr

Gathering data at the summit of Garnedd Wen

By now the first clouds had bubbled up in an otherwise spotless blue sky, and by the time I retraced my steps back down the hill to the narrow road more clouds had appeared.  After taking a data set at one of two possible bwlch positions of Mynydd Mawr I slowly plodded up beside a fence toward its summit, the north-easterly ridge of this hill is relatively broad and long, and gave chance for my mind to wander as height was slowly gained.

The summit of Mynydd Mawr is crowned by a triangulation pillar with elevated land approximately 5 metres to its west and 19 metres to its east, with the high point of each on exposed rock that forms a small rock crest which is more prominent on the eastern side.  I took data sets from each high point before setting off back on my inward route.

Gathering data from the point 5 metres west of the trig pillar on Mynydd Mawr

Gathering data from the point 19 metres east of the trig pillar on Mynydd Mawr

The Trimble set-up position at the summit of Mynyd Mawr with the trig pillar in the background

Following the fence line back down the hill the profile of Y Gurn looked forever majestic, a wonderful hill considering its relatively lowly height.  All that remained was to take a second data set from the continuation of the land that makes up the bwlch of Mynydd Mawr, this time from the position that I considered to be the critical point, as this was beside a gate that led to the narrow road where my car was parked it was a convenient place to end the day’s surveying.

Y Gurn (SJ 184 293)

Gathering data at the critical bwlch of Mynydd Mawr

The walk proved ideal in length to test my recently operated on right knee, and was also ideal to re-accustom myself to the hills and using the Trimble after a two month layoff.  



Survey Result:


Garnedd Wen 

Summit Height:  496.0m (converted to OSGM15) 
 
Summit Grid Reference:  SJ 13181 31156

Bwlch Height:  472.3m (converted to OSGM15)

Bwlch Grid Reference:  SJ 13046 31401

Drop:  23.8m (400m Sub-Pedwar status confirmed)

Dominance:  4.79%




Mynydd Mawr

Summit Height:  534.7m (converted to OSGM15)  

Summit Grid Reference:  SJ 13306 28624

Bwlch Height:  430.0m (converted to OSGM15)

Bwlch Grid Reference:  SJ 14135 30581

Drop:  104.6m (Hump status confirmed)

Dominance:  19.57%







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