Showing posts with label Cefn Brân. Show all posts
Showing posts with label Cefn Brân. Show all posts

Friday, 15 July 2022

Mapping Mountains – Hill Reclassifications – Y Trichant – The 300m Hills of Wales


Cefn Brân (SJ 096 199) – Sub-Trichant reclassified to Trichant

There has been confirmation of a reclassification to the list of Y Trichant – The 300m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill derived from a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips. 

Cefn Brân (SJ 096 199)

The criteria for the list that this reclassification applies to are:

Y Trichant – The 300m Hills of Wales – Welsh hills at or above 300m and below 400m in height that have 30m minimum drop, with an accompanying sub list entitled the Sub-Trichant, with the criteria for this sub category being all Welsh hills at or above 300m and below 400m in height with 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips with the Introduction to the list and the renaming of it appearing on Mapping Mountains on the 13th May 2017, and the Introduction to the Mapping Mountains publication of the list appearing on the 1st January 2022.

The name the hill is listed by is Cefn Brân, and it is adjoined to the Foel Cedig group of hills, which are situated in the southern part of North Wales (Region A, Sub-Region A3), and it is positioned encircled by minor roads, with the B4391 road farther to its north-east, the B4396 road farther to its west and the B4393 road farther to its south, and has the town of Llanfyllin towards the east.

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was included in the Hills to be surveyed sub list, as it was considered not to meet the criteria then used for the main P30 category.

When the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed with an estimated c 29m of drop, based on the 391m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 362m bwlch height, based on interpolation of 10m contouring between 360m – 370m. 

Extract from the Ordnance Survey 1:25,000 Explorer map

Since the original publication of the Welsh P30 lists on Geoff Crowder’s v-g.me website there have been a number of maps made available online.  Some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website.  Whilst others were digitally updated such as the Ordnance Survey Vector Map Local that was hosted on the Geograph website and which was entitled the Interactive Coverage Map, whilst others are current and digitally updated such as the interactive mapping on the Magic Maps and WalkLakes websites.

The details for this hill were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available Ordnance Survey maps and for this hill it had a 361m bwlch spot height and when coupled with the 391m summit spot height, these values gave this hill 30m of drop. 

The Trimble GeoXH 6000 gathering data at the summit of Cefn Brân

The Trimble GeoXH 6000 gathering data at the bwlch of Cefn Brân

However, it was not until the Trimble GeoXH 6000 survey was conducted that accurate heights and positions for this hill could be obtained, and it is these data that confirm the reclassification of this hill.

Therefore, the confirmation of the reclassification of this hill from Sub-Trichant status is due to a Trimble GeoXH 6000 survey, resulting in a 391.3m summit height and a 361.3m bwlch height, with these values giving this hill 30.1m of drop, which is sufficient for it to be classified as a Trichant. 

 

The full details for the hill are: 

Group:  Foel Cedig 

Name:  Cefn Brân 

OS 1:50,000 map:  125

Summit Height:  391.3m (converted to OSGM15)  

Summit Grid Reference:  SJ 09634 19959 

Bwlch Height:  361.3m (converted to OSGM15) 

Bwlch Grid Reference:  SJ 09289 20126 

Drop:  30.1m 

 

Myrddyn Phillips (July 2022)

 



 

 

 

 

 

  

Sunday, 27 August 2017

Mapping Mountains – Trimble Surveys – Foel Cedig



17.06.17  Cefn Brân (SJ 096 199), Pen y Bylchau (SJ 062 203) and Y Glog (SJ 088 207)

Y Glog (SJ 088 207)

Having had the pleasure of an evening’s company with Alan Dawson I headed out the following morning in beautiful blue skied conditions, whilst Alan set off to meet his sister for a walk up Cadair Idris.  My destination was not as ambitious and consisted of a couple of hills above Llanfyllin.

Parking my car I sauntered down the narrow lane aiming for a public footpath that led across fields toward a high lane where the first summit of the day was closely positioned.  There was intensity to the heat, thankfully this was dry and not a humid overbearing and oppressive heat, with colours bouncing across the land as a deep blue sky radiated from above.

Cefn Brân (SJ 096 199) from the lane leading to Hafod

The path led past the farm of Hafod and continued up slumbering fields where sheep were haphazardly placed nonchalantly grazing, as the path continued below a conifer plantation positioned to the south of the high lane and towering up the hillside, the summer growth almost became overwhelming with fern sprouting waist high and stunted trees overhanging the lower hillside.  Picking a way through I found what I thought to be the continuation of the path and followed it up to open fields and the high lane beyond, with the summit of my first hill; Cefn Brân now being only a short distance away.

I stopped before the summit to talk to a farmer who was mending the fence on the south-western side of the high lane.  We chatted for quite some time, pointing out the far hills and commenting on how beautiful this part of the country is.  He had no objection to me visiting the summit, and so I headed off to find its high point and set the Trimble up to gather its allotted five minutes of data.

Gathering data at the summit of Cefn Brân

Once data were stored and the Trimble packed away I walked back to the farmer for another chat and then proceeded down the lane to where the critical bwlch of Cefn Brân is situated.  I’d taken a Google car over this spot the previous evening and judged that the critical point of the bwlch was placed on the lane close to where the 361m spot height appears on the Ordnance Survey enlarged mapping hosted on the Geograph website.  Arriving at the low point of the lane I peered through the hedge on its northern side and walked up the western part of the lane to look back down on the area of the bwlch, I picked my spot and positioned the Trimble and then repeated what I had just done, by doing so I noted the marshy land on the north of the lane and where it bisected the paved narrow road, I re-positioned the Trimble by a few metres and then repeated the whole process again, eventually I moved the Trimble from the side of the lane into the middle of the narrow road and once the 0.1m accuracy level had been obtained, I pressed Log and scampered off hoping that a rogue car would not appear in the next five minutes, thankfully none did, and once the allotted 300 datum points were stored I took a series of photographs, switched the equipment off and continued on the narrow lane heading toward the critical bwlch of Y Glog, which is placed close to a sharp corner in the road and where it bisects with a number of tracks.

Gathering data at the critical bwlch of Cefn Brân

When on top of Cefn Brân I’d noticed that forestry had been felled on a summit beyond Y Glog, and studying the map it looked as if it was the summit of Pen y Bylchau, which is listed as a Pedwar.  The easiest route to the summit of this hill was from the sharp bend in the narrow lane that I was now heading toward and then up one of the tracks that bisect it.  Although concerned that the extra couple of miles from this bwlch to the top and back may prove problematic for my wonky knee I decided the opportunity to Trimble a summit that has been immersed in conifer plantation for years was one not to miss.

Once at the sharp bend in the narrow road I spent a number of minutes assessing the lay of land before choosing the spot for Trimble placement, this proved to be near an overhanging tree and it took an inordinate amount of time for the o.1m accuracy level to be attained before data should be logged, I spent this time sitting on a felled bough of a tree, in the shade as the sun roasted down.

Gathering data at the critical bwlch of Y Glog

As the Trimble beeped away collecting its 300 allotted datum points my mind wandered to all manner of places, once five minutes were up I switched the Trimble off, packed it away and headed up one of the tracks, this soon petered out to a vehicle track that headed toward a gate.  I then followed a fence line across rougher grass land toward a slow and sweat induced last uphill toward the summit, crossing the fence I stumbled through the customary chaos of felled conifer plantation to what I judged to be the high point, this I again assessed from a number of directions and once happy with the Trimble placement I sat on a near tree stump, basking in the sun as five minutes of data were gathered.

Cefn Brân from the lower slopes of Pen y Bylchau

The approach to Pen y Bylchau

Gathering data at the summit of Pen y Bylchau (SJ 062 203)

Across the intervening valley the sun drenched top of Rhialgwm looked impressive above its conifered lower south-eastern slopes, whilst far off to the west the shapely profile of Cadair Idris stood out with Alan and his sister somewhere near its summit.

The shapely profile of Cadair Idris which Alan Dawson was surveying at just about the same time

After stumbling my way back through the debris of felled forestry I followed a different vehicle track down the hill, only cutting across the slopes lower down to re-join my inward route back to the sharp bend in the lane, and then onward back up the lane to where it intersects with another narrow road that would eventually lead me back to my car.

Delicate clouds out to the north on the way toward Y Glog

I left the lane where a gate gave access toward the southern slopes of Y Glog and followed a fence line toward its summit, once at the top I checked the ten figure grid reference I’d noted from the Hill Bagging website and found that the point where I judged to be highest was the farthest west of three rises, with the one farthest east obviously lower.  Before activating the Trimble I checked the central top against the more westerly and still thought the westerly summit to be higher, as the Trimble gathered data on the westerly high point I decided I should also gather data from the central top, and to complete proceedings I thought I’d better also gather data from the lower easterly top, by doing so there would be a good comparison between the Trimble data and map spot heights, and I’ve also learnt that if presented with an opportunity to put an accurate height on a hill then do it, as the opportunity to do so may never present itself again.

Gathering data at the summit of Y Glog

During these three data sets I stood in the sun keeping my eye on any rogue wandering sheep nearing the Trimble, I also rested, luxuriating myself in warmth and happy in the knowledge that another three summits had been Trimbled.

The descent route although simple and relatively short was a joy, as the whole area was quiet and devoid of activity, I followed the easterly grassed ridge of Y Glog down to a gate which gave access back on to the narrow country lane and then wandered down to my car.  It had been a hot but very enjoyable few hours on the hill, all that remained was a drive to Oswestry to visit Lou for the evening.



Survey Result:



Cefn Brân  

Summit Height:  391.3m (converted to OSGM15) 
 
Summit Grid Reference:  SJ 09634 19959

Bwlch Height:  361.3m (converted to OSGM15)

Bwlch Grid Reference:  SJ 09289 20126


Dominance:  7.68%





Pen y Bylchau

Summit Height:  456.7m (converted to OSGM15) 
 
Summit Grid Reference:  SJ 06218 20307

Bwlch Height:  c 371m (interpolation)

Bwlch Grid Reference:  SJ 07137 21187 (interpolation)

Drop:  c 86m

Dominance:  18.76%





Y Glog

Summit Height:  408.2m (converted to OSGM15) 
 
Summit Grid Reference:  SJ 08867 20735

Bwlch Height:  346.3m (converted to OSGM15)

Bwlch Grid Reference:  SJ 07784 20140

Drop:  61.9m

Dominance:  15.16%