Saturday, 5 September 2015

Mapping Mountains – Trimble Surveys – Y Cymoedd


12.08.15  Bryn Serth (SO 147 109)  

Bryn Serth (SO 147 109)

Bryn Serth stands on the outskirts of Tredegar at the head of the Cwm Sirhywi (Sirhowey Valley) in the heartland of south Wales.  The hill is listed as a Pedwar with c 34m of drop and was suggested by Mark to form part of our days outing to the south, which proved part bagging and part cultural as the hill looks down on the Aneurin Bevan Memorial.

Pay due deference toward a man of vision

Aneurin Bevan’s legacy is still predominant in the politics of today as he was the founding father of the National Health Service, and the memorial was erected in his memory to mark the place where he held open air meetings to speak to his constituents.

This stone plaque is laid into the wall surrounding the Memorial

The Memorial consists of four upright monoliths, all broad in nature with the centrally based one being the largest; this represents Nye himself, with the other three representing his constituents in Ebbw Vale, Tredegar and Rhymney.

This bold monolith represents Nye

The Memorial stands beside the busy A4047 which cuts a swathe across the land in a south-west to north-east direction.  Adjacent to the Memorial is a car park, this area also holds that of the critical bwlch of the hill.

We arrived as 12.45pm having had a pleasant drive south consisting of good conversation and a stop for eateries and refreshment on the way.  Our visit to the Memorial and the bwlch could wait as our objective for now, was the summit.  This is given as c 410m in Y Pedwarau as its uppermost 410m contour is very small and photographic evidence of the hill shows it as being relatively flat on top.

A track leaves the confines of the car park and heads off north-westward over the land toward the hill; it soon swings north-eastward, at this point a path climbs the hill’s southern flank.  It was here that a pane of broken glass lay smashed and abandoned on the track, an unfortunate reminder that outdoor beauty can be easily despoiled.

The track leading to the summit of Bryn Serth

An unfortunate addition to some parts of the hills

As we arrived on the summit area Mark walked toward where the ten figure grid reference for the uppermost contour ring was situated on the ground, once there we looked further north and both agreed that higher ground lay a 100 metres or so further on.

Once at the point that we both agreed was the highest for the hill I nestled the Trimble down on the top of my rucksack, using the latter as an improvised tripod as the grass hereabouts was long and would no doubt submerge the Trimble if it was laid on the ground and possibly interfere with satellite coverage.  I measured the offset between the ground at the base of the rucksack and the point of the internal antenna in the Trimble as 0.44m.

Gathering data from the summit of Bryn Serth

As the Trimble gathered its data we looked out on the beauty of south Wales as one extended ridge led to another, once five minutes of data were collected I packed the equipment away and we re-joined the path and headed back toward the car.  However, I still wanted a data set from the position of the uppermost contour ring, so as Mark walked back to the car and paid a visit to the Memorial I set the Trimble up for another five minute data collection.  Once complete I joined Mark at the car.

The second data set was taken from where the c 410m ring contour appears on current Ordnance Survey maps

We’d certainly been lucky with the weather as this day in south Wales had been booked a few weeks in advance, and the weather forecast was for sunshine and a light breeze and as I walked the last few metres toward the car park the pleasant afternoon’s warmth pervaded the land.

By the time I walked back to the car park Mark was already busy looking at the lay of land around the area of the road and the entrance into the car park, within a few minutes we had decided where the critical bwlch lay and as Mark headed back to the car I set the Trimble up on the top of my rucksack on the corner of the pavement, adjacent to the busy road and wondered why I hadn’t done this those many months ago when it had been run over on the edge of a pavement in Mold.

Gathering data at the critical bwlch of Bryn Serth

As the traffic passed, the Trimble contentedly went about its business gathering five minutes of data, after I packed it away I quickly visited Mark and then headed up the path to the Memorial Stones.

Placing the Trimble on top of a ruck sack makes an excellent improvised tripod

I paid my respects to Nye and looked out on the landscape he called home; it is a landscape of urban development, past industrial heritage and one of hills.  Soon afterward I was back at the car and we headed toward Trefil and our next walk of the day.

Three of the four monoliths at the Aneurin Bevan Memorial

Survey Result:


Bryn Serth

Summit Height:  403.9m (converted to OSGM15) (significant height revision)

Summit Grid Reference:  SO 14794 10908 (summit relocation confirmed)

Bwlch Height:  378.6m (converted to OSGM15)

Bwlch Grid Reference:  SO 15082 10473

Drop:  25.4m (Pedwar reclassified to 400m Sub-Pedwar)

Dominance:  6.28%



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


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