Mapping Mountains – Significant Height Revisions – Y Pedwarau

Bryn Serth (SO 148 109)  

There has been a Significant Height Revision to a hill that is listed in the Y Pedwarau that was initiated by a survey with the Trimble GeoXH 6000 and subsequently confirmed via LIDAR analysis conducted by Aled Williams, with these details being retrospective as the Trimble survey that resulted in this height revision was conducted on 12^th August 2015.  The hill appeared in the listing of Y Pedwarau as a Pedwar with c 34m of drop and was reclassified to a 400m Sub-Pedwar due to the survey with the Trimble GeoXH 6000. 

The criteria for Pedwar status is all Welsh hills at or above 400m and below 500m in height that have 30m minimum drop.  Whilst the criteria for 400m Sub-Pedwar status is all Welsh hills at or above 400m and below 500m in height that have 20m or more and below 30m of drop.

The name of the hill is Bryn Serth and it is situated in the hill range known as Cymoedd Gwent which is positioned in south Wales, and the survey was conducted during a walk in the company of Mark Trengove who had suggested visiting the hill.

Bryn Serth is situated on the northern outskirts of Tredegar at the head of the Cwm Sirhywi (Sirhowey Valley) and it can be easily accessed from a car park beside the busy A4047 which is positioned south-east of the summit.  This car park also gives access to the Aneurin Bevan Memorial Stones; these consist of four monoliths and are set against the landscape of Ebbw Vale, Tredegar and Rhymney which form the constituencies which Aneurin Bevan represented during his years in Westminster.

Prior to the survey with the Trimble GeoXH 6000 the hill was listed as a Pedwar with its summit height estimated as c 410m based on a small uppermost 410m ring contour that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps.  However, this point is not the high point of the hill as land approximately 100 metres further north was surveyed with the Trimble as being 2.0m higher than the position where the uppermost contour ring appears on the ground.

The two points surveyed with the Trimble GeoXH 6000 gave results that are significantly lower than current Ordnance Survey map data, these results are:

Northern summit:  403.927m (converted to OSGM15) at SO 14794 10908

Southern summit:  401.890m (converted to OSGM15) at SO 14782 10809

It is the southern summit where the small 410m ring contour appears on contemporary Ordnance Survey maps.

Since processing the data sets from this survey Aled has scrutinised on-line mapping and found that the Ordnance Survey Six-Inch map has a 1,327ft (404.47m) height on the area of the summit and a 1,242.5ft (378.71m) height on the area of the bwlch.  These Six-Inch map values give Bryn Serth a drop of 25.76m which is comparable to the result produced by the Trimble GeoXH 6000 and by LIDAR analysis.

Therefore, this hill’s new summit height is 404.0m and this was derived from LIDAR analysis, and thus is 6m lower than its previously estimated height of c 410m and its uppermost ring contour on Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps.

The full details for the hill are:

Group:  Cymoedd Gwent

Summit Height (New Height):  404.0m (LIDAR)

Name:  Bryn Serth

OS 1:50,000 map:  161

Summit Grid Reference:  SO 14807 10929 (LIDAR)

Drop:  25.8m (LIDAR)

Gathering data at the summit of Bryn Serth which resulted in this hill's significant height revision

For details on the survey that significantly revised the summit height of this hill

Myrddyn Phillips and Aled Williams (September 2015)

Mapping Mountains – Summit Relocations – Y Pedwarau

Bryn Serth (SO 148 109)  

There has been a Summit Relocation to the listing of Y Pedwarau initiated from a survey with the Trimble GeoXH 6000 and subsequently confirmed from LIDAR analysis, with the latter conducted by Aled Williams.  The list of the Y Pedwarau takes in all 400m Welsh hills that have a minimum drop of 30m, with the Trimble survey that resulted in the following details taking place on 12^th August 2015.

Accompanying the Y Pedwarau list are a number of sub category's of hills, with this hill being listed as a 400m Sub-Pedwar, these are the Welsh 400m hills that have 20m or more and below 30m of drop.

The hill is positioned in the group known as Cymoedd Gwent in south Wales, and it was surveyed during a walk in the company of Mark Trengove on a bright and cheerful day.  The hill is situated on the northern outskirts of Tredegar at the head of the Cwm Sirhywi (Sirhowey Valley) and it can be easily accessed from a car park beside the busy A4047 which is positioned at its south-eastern base.  This car park also gives access to the Aneurin Bevan Memorial Stones; these consist of four monoliths and are set against the landscape of Ebbw Vale, Tredegar and Rhymney which form the constituencies which Aneurin Bevan represented during his years in Westminster.

The name of the hill is Bryn Serth and prior to the survey with the Trimble GeoXH 6000 it was listed as a Pedwar with its summit position given as SO 147 108 which is the centralised position of its uppermost 410m ring contour that appears on current Ordnance Survey maps, with this ring contour being erroneous as there is no land on this hill that reaches the height of this contour.  However, this position is not the high point of the hill as land approximately 100 metres further north was surveyed by the Trimble as being 2.0m higher.

The position of the relocated summit is at SO 14807 10929 and is the top of featureless ground that mainly consists of long grass, this position is not given a spot height on contemporary Ordnance Survey maps but the Trimble and LIDAR result gave it as 2.0m higher when compared to the land where the uppermost ring contour appears on the ground.

The full details for the hill are:

Group:  Cymoedd Gwent

Summit Height:  404.0m (LIDAR)

Name:  Bryn Serth

OS 1:50,000 map:  161

Summit Grid Reference (New Position):  SO 14807 10929 (LIDAR)

Drop:  25.8m (LIDAR)

The Trimble GeoXH 6000 set-up position at the summit of Bryn Serth, with the old position of the summit in the background of this photograph

For details on the survey that relocated the summit of this hill please click {here}

Myrddyn Phillips and Aled Williams (August 2015)

Mapping Mountains – Hill Reclassifications – Y Pedwarau

Bryn Serth (SO 148 109) - Pedwar reclassified to 400m Sub-Pedwar  

There has been another reclassification of a Pedwar to a 400m Sub-Pedwar through surveying with the Trimble GeoXH 6000 and which was subsequently confirmed via LIDAR analysis, with the latter conducted by Aled Williams.   The hill is situated in the South Wales Cymoedd Gwent range of hills, and is positioned on the northern outskirts of Tredegar beside the A4047 at the head of the Cwm Sirhywi (Sirhowey Valley).

The hill is named Bryn Serth (SO 147 109) and it is given c 34m of drop in the 1^st edition of the Y Pedwarau published by Europeaklist.  This drop figure is based on an estimated c 410m summit height which has a small 410m uppermost contour ring and an estimated bwlch height of c 376m.  The area of the bwlch has a 376m spot height on contemporary Ordnance Survey maps but its position was judged not to be at the critical bwlch.

The hill was surveyed in the company of Mark Trengove who had suggested the walk and muttered disillusionment when told that the hill was no longer a Pedwar due to the survey that had taken place, as it brings his total of Pedwarau bagged in Section 32C back down to zero!

This now brings the overall total for the Y Pedwarau to 449 hills with five additions and three deletions since publication of the list by Europeaklist in May 2013.  The hill will be taken out of the main list and added to the 400m Sub-Pedwar list in the 2^nd edition planned for publication by Europeaklist.  The list of Pedwar hills is also available from the Haroldstreet website.

The full details for the hill are:

Group:  Cymoedd Gwent

Summit Height:  404.0m (LIDAR)

Name:  Bryn Serth

OS 1:50,000 map:  161

Summit Grid Reference:  SO 14807 10929 (LIDAR)

Drop:  25.8m (LIDAR)

The list of additions and deletions from the main Pedwar list since the 1^st edition of Y Pedwarau was published by Europeaklist are as follows:

ADDITIONS

Y Garn (SH 758 375)

Cefn Perfa (SO 173 579)

Craig y Ganllwyd (SH 707 258)

Pt. 499m (SH 665 310)

Mynydd Poeth (SH 953 513)

RECLASSIFICATIONS

Pt. 422m (SO 073 822)

Wenallt (SN 933 571)

Bryn Serth (SO 147 109)

Bryn Serth (SO 148 109) now reclassified from Pedwar to 400m Sub-Pedwar status

For details on the survey that reclassified this hill from Pedwar to 400m Sub-Pedwar status please click {here}

Myrddyn Phillips and Aled Williams (August 2015)

Mapping Mountains – Trimble Surveys – Cymoedd Gwent

12.08.15  Bryn Serth (SO 148 109)  

Bryn Serth (SO 148 109)

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 contemporary 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 chosen the point to survey 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.

The Trimble set-up position for the bwlch survey 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:  404.0m (LIDAR) (significant height revision)

Summit Grid Reference:  SO 14807 10929 (LIDAR) (summit relocation confirmed)

Bwlch Height:  378.2m (LIDAR)

Bwlch Grid Reference:  SO 15083 10507 (LIDAR)

Drop:  25.8m (LIDAR) (Pedwar reclassified to 400m Sub-Pedwar)

Dominance:  6.39% (LIDAR)

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