Mapping Mountains – Summit Relocations – Yr Uchafion and 500m Twmpau

Mynydd Ystradffernol (SN 937 009)

There has been a Summit Relocation to a hill that is listed in the Yr Uchafion and the 500m Twmpau, with the summit height, drop and status of the hill being confirmed by a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips on the 25^th August 2018.

Mynydd Ystradffernol (SN 937 009)

The criteria for the two listings that this summit relocation applies to are:

Yr Uchafion – Welsh hills at or above 500m in height that have 15m minimum drop.  The list is co-authored by Myrddyn Phillips and Aled Williams, with the Introduction to this list appearing on Mapping Mountains on the 4^th November 2015.

500m Twmpau – Welsh hills at or above 500m and below 600m in height that have 30m minimum drop, with an accompanying sub category entitled the 500m Sub-Twmpau consisting of all Welsh hills at or above 500m and below 600m in height that have 20m or more and below 30m of drop.  With the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.  The list is authored by Myrddyn Phillips.

The name of the hill is Mynydd Ystradffernol, and it is adjoined to the Cymoedd Gwent range of hills, which are situated in the central part of South Wales (Region C, Sub-Region C2), and is positioned with the A 4061 road to the west and has the village of Treherbert towards the south.

As the summit of the hill is a part of designated open access land it can in theory be approached from any direction.  However, the hill is covered in an extensive conifer plantation which over recent years now incorporates many wind turbines.  The building of the wind farm has created access tracks and these can be used to ease passage toward the summit. 

Prior to the survey with the Trimble GeoXH 6000 the summit of this hill was listed near to where the 518m summit spot height appears on the Ordnance Survey 1:25,000 Explorer map, this position is at SN 93682 00905.

Two surveys were taken with the Trimble GeoXH 6000 with the following results:

1^st survey:  517.808m at SN 93790 00902

2^nd survey:  517.612m at SN 93676 00907

Gathering data at the summit of Mynydd Ystradffernol

The second data set taken for the summit position of Mynydd Ystradffernol

The second survey was taken to the highest ground close to where the 518m spot height appears on the Ordnance Survey 1:25,000 Explorer map.  However, the result produced by the Trimble for the first survey is higher and its position comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies to any listed hill whose summit meets the following criteria; where there are a number of potential summit positions within close proximity and the highest point is not where previously given, or a relocation of approximately 100 metres or more in distance from either the position of a map spot height or from where the summit of the hill was previously thought to exist, or when the summit of the hill is in a different field compared to where previously given, or when the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary that is judged to be a relatively recent man-made construct.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 Explorer map is being prioritised in favour of the 1:50,000 Landranger map for detailing these relocations.

Extract from the Ordnance Survey 1:25,000 Explorer map showing the new summit position in relation to the old listed summit position at the 518m spot height

The summit height produced by the Trimble GeoXH 6000 survey is 517.8m and is positioned at SN 93790 00902.  This position is not given a spot height on Ordnance Survey maps and is approximately 100 metres east from where the previously listed summit position is situated.

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Cymoedd Gwent

Name:  Mynydd Ystradffernol

OS 1:50,000 map:  170

Summit Height:  517.8m (converted to OSGM15)

Summit Grid Reference (new position):  SN 93790 00902

  

Bwlch Height:  484.9m (converted to OSGM15)

Bwlch Grid Reference:  SN 92961 02194

Drop:  32.9m (converted to OSGM15)

For details on the survey that confirmed the summit relocation of this hill

Myrddyn Phillips and Aled Williams (January 2019)

Mapping Mountains – Trimble Surveys – Cymoedd Gwent

25.08.18  Mynydd Ystradffernol (SN 937 009)  

Mynydd Ystradffernol (SN 937 009)

I’d visited Mynydd Ystradffernol twice before, the first time just to its 516m trig pillar which is situated on the southern part of its uppermost 510m ring contour, whilst on the second visit I floundered in the conifer plantation that encloses the upper part of this hill reaching a point I judged to be the highest amongst the trees, but today with the assistance of Mark and Aled I had every intention to reach the high point of a forest break that many consider the true summit of this hill.

We parked beside the A 4061 road in a car park full of back-up vehicles associated with the SD Sealants Junior Tour of Wales 2018, whose second stage had just finished.  From here a path leads eastward skirting mature conifers to an access track for the large wind farm that now dominates this hill.

Heading toward the access track beside the turbines

The access track certainly eased progress and it conveniently led down toward the connecting bwlch of this hill.  This was positioned in a watery bog and my colleagues judged the critical point to be placed just to the west of the track, I decided that it was safer for the Trimble to be placed on terra-firma and we proceeded to take a measurement offset using a walking pole and a small spirit level placed at a 1m height, between the watery lagoon and the Trimble set-up position, once completed Mark and Aled sauntered off to sit beside one of the large turbines whilst the Trimble gathered its allotted data.

The Trimble set-up position at the bwlch of Mynydd Ystradffernol

Aled and Mark waiting beside one of the turbines for the survey at the bwlch to be completed

Once data were stored I packed the Trimble away and we continued heading south-eastward to the end of the track, we now had two options for our onward route to the summit and decided on the one directly in front, this consisted of a wide forest break which I had walked down in the opposite direction on my second visit to this hill, it led over ground reclaimed from felled forestry up to a fallen tree which barred direct access, once past this we joined the forest break that would take us toward two points that vie for the accepted summit of this hill.

Heading up the first forest break from the end of the access track toward where a fallen tree bars direct progress

Heading up the second forest break toward the summit which is just around the corner on the right

The first of these was in a small clearing and this at least gave hope of a good data set being gathered by the Trimble, and once the 0.1m accuracy level was attained I pressed ‘Log’ and sat beside Aled and waited for the allotted data to be gathered and stored, during which Mark ventured further down the continuation of the forest break to investigate the second high point that vies for the recognised summit of this hill.

Gathering data at the summit of Mynydd Ystradffernol

After the Trimble was closed down Aled and I investigated land close to its set-up position but within the trees and improvised a levelling method to measure back from this point to the Trimble set-up position in the clearing, the height difference came to 3cm, therefore we concluded the ground hereabouts was of equal height.

As we set off toward the other high point which was immersed in trees Mark was walking back toward us, and although he thought it next to impossible for the Trimble to gather data amongst the trees, we proceeded to the point Mark had found and miraculously the Trimble attained its 0.1m accuracy level relatively quickly and another seven minute data set was gathered and stored.

The Trimble set-up position at the second point surveyed for the summit of Mynydd Ystradffernol

Once the second Trimble summit data set was complete the equipment was closed down and Aled and I re-joined Mark at the small clearing and retraced our route out of the trees, back on to the track which took us northward toward my car.

Heading back to re-join Mark who was waiting in the small clearing

Mark bi-passing the fallen tree on our way back toward the access track

By now the sun was casting late afternoon colour across the land, and we thought our optional fourth walk may have to be postponed for another day, but we still had time to visit Mynydd Ton.

Survey Result:

Mynydd Ystradffernol

Summit Height:  517.8m (converted to OSGM15)

Summit Grid Reference:  SN 93790 00902 (summit relocation confirmed)

Bwlch Height:  484.9m (converted to OSGM15)

Bwlch Grid Reference:  SN 92961 02194

Drop:  32.9m (500m Twmpau status confirmed)

Dominance:  6.35%

For details on the previous visit to this hill

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Trimble Surveys – Cymoedd

23.07.16  Mynydd Ystradffernol (SN 937 009, not surveyed)    

Mynydd Ystradffernol (SN 936 009) with Fan Fawr and part of the Bannau Brycheiniog in the background

Mynydd Ystradffernol stands between the Rhondda Fach and Rhondda Fawr valleys and to its west its adjacent hill is Craig y Llyn; this being the highest hill in the south Wales valleys.  Since my last visit Mynydd Ystradffernol has undergone a transformation as the Pen y Cymoedd Wind Energy Project by Vattenfall has installed many wind turbines resulting in great swathes of conifered forestry being cut back.  This at least gives easier access to the area of the summit and also offers alternative routes to the top.

I set off on one of the forestry tracks that head toward the hill from the A 4061 as it crests its high point between Hirwaun to the north and Treherbert to the south.  I’d come prepared with a series of ten figure grid references for many forest track junctions and forest breaks which were situated  between my setting off point and the forest break that seemed to give easiest and quickest access to the high point of the hill.

It seemed unusual to see turbines poking up above the trees, I hadn’t been on this hill for a number of years and some hills significantly change over time, and this is one that is doing so as the wind energy project is not yet finished.

Reaching my cut off point I checked the grid reference for the forest break I wanted to take and headed up over horrendous tussocks in warmer and muggier conditions.  My going slowed as the tussocks proved unwelcome and it looked as if large parts of the forest break had once been covered in conifers resulting in small narrow ditches being hidden amongst the long grass.  However, bit by bit I gained height and decided to follow the very wide break around to my right where it seemed to penetrate the upper slopes of the hill the greatest, this was a mistake as it took me away from the summit in to the trees, I didn’t realise this at the time as all I was looking for was easiest passage to the summit.  It got to a point that I thought it more difficult to backtrack than go forward, so I carried on.  By now I was in the trees contouring around the upper part of the hill trying to get out on to open ground next to a wind turbine whose blades were on show sticking out above the trees.

I bashed through the last bit of conifers and popped out to sunshine and a few metres later was standing beside one of the newly installed wind turbines with the summit of the hill behind me to the west.  I was now much farther away from the summit when compared to where I’d been when on part of the forest break!

Not perturbed I decided that the wind turbines must be joined by tracks and as there was another one off in the distance close to where the summit was I headed in its direction.  However, I couldn’t find a connecting track but did find a forest break that took me in the right direction, only for two fallen trees to bar my progress; I bashed through them as best I could and emerged on the other side. 

Onward route through the trees

The forest break I was now on was close to the high point and I decided that I should at least gather data from two points adjacent to the trees on ground that rose in to them.  This took an inordinate amount of time as it took an age for the Trimble to ebb down to its 0.1m accuracy level before data should be logged.  Once two data sets were gathered I ventured in to the trees and wandered around visiting any high point I could find.

Gathering the first data set beside the trees on Mynydd Ystradffernol

Gathering the second data set beside the trees on Mynydd Ystradffernol

Once out of the trees I stumbled down to the nearest wind turbine and followed its adjacent track north-westward across the upper ridge of the hill toward two vehicles parked next to one of the turbines whose body was upright but whose blades were prostrate, awaiting the day of their instalment, they looked huge.

One of the blades for the wind turbines

Looking south south-east toward the summit of Mynydd Ystradffernol

As I approached this area another vehicle drove up the connecting track from the east, I flagged it down to check on the best track to use to get back on to the A 4061, within a few minutes I was sitting in the vehicle as it sped down the track, this gave me a rest from the forest and the trees and the thought of further conifer bashing.

I was fortunate to get a lift down the remainder of the forestry track

When we reached the A 4061 I thanked the driver and walked down the remainder of the road toward my awaiting car, next stop Mynydd Ton.

 

 

Hill's Details:

Mynydd Ystradffernol

Summit Height:  517.8m (converted to OSGM15, from subsequent Trimble survey)

Summit Grid Reference:  SN 93790 00902 (from subsequent Trimble survey)

Bwlch Height:  484.9m (converted to OSGM15, from subsequent Trimble survey) 

Bwlch Grid Reference:  SN 92961 02194 (from subsequent Trimble survey)

Drop:  32.9m (from subsequent Trimble survey)

Dominance:  6.35% (from subsequent Trimble survey)

For details on the summit and bwlch survey of this hill

For further details please consult the Trimble survey spreadsheet