Friday, 10 June 2022

Mapping Mountains – Trimble Surveys – Arenig Fach


18.04.22  Chwarel Graig Ddu (SH 725 455), Pt. 658.45m (SH 727 458), Pt. 643.1m (SH 727 460), Pt. 535.0m (SH 723 461), Pt. 516.9m (SH 724 465) and Pt. 519.2m (SH 721 463)

Chwarel Graig Ddu (SH 725 455)

A tremendous amount of activity has been directed toward the discovery and confirmation of hills for Welsh 2,000ft (609.6m) P15 status.  This can be traced back to the 1920s when Arthur St George Walsh first compiled his list to these hills.  Not surprisingly Arthur worked purely in imperial measurement with a 2,000ft minimum height and a 50ft minimum drop criteria, although we do not know his exact methods, we do know that he was meticulous in his cataloguing of hills for this list.

In the late 1980s John and Anne Nuttall compiled their guide to Welsh hills using this same criteria.  Importantly they developed a surveying method that enabled many marginal hills to be either included or set to one side.  Their list was later augmented with survey results produced by Dewi Jones and soon afterward by me.  During this time I compiled a Welsh list using 500m minimum height and 15m minimum drop, which under the co-authorship of Aled Williams has since evolved into The Welsh Highlands list.  A sub-set within this list is the higher tier above 609.6m in height.  This higher tier is not a duplication of John and Anne’s work, or earlier lists such as Walsh’s for that matter.  Ever since its first compilation it has included hills not in the Nuttall’s list; for example, Castell y Gwynt and Fronllwyd, and it has also excluded hills listed by the Nuttalls; for example, Carnedd y Ddelw and Pt. 637.1m.

The surveying activity for these criteria was significantly expanded by John Barnard, Graham Jackson and myself who concentrated on the marginal hills produced by my previous surveys.  Using a level and staff and Leica GNSS equipment dramatically increased the accuracy of the results.  This has now been expanded by the use of the Trimble GeoXH 6000 and the availability of LIDAR.  By now it seemed all possible hills that stood any chance of inclusion to this height and drop category had been surveyed.  But this premise was wrong.  One last hill lurked in the background awaiting discovery!

The potential of the hill in question was first spotted by Aled Williams whilst scrutinising online 5m map contouring.  This was approximately two years ago and this hill had been on our radar ever since as this map has an uppermost 610m contour and bwlch contours between 590m – 595m.  However, as this hill is a part of a working quarry our intention was to inspect it from adjacent hillsides and hopefully confirm its validity. 

The map giving 5m contours 

The hill in question is positioned above Blaenau Ffestiniog in the heartland of Welsh slate mining and not surprisingly it has been terra-formed due to quarrying activity.  Hills created by man-made influence are shunned by some people, but there are many similar hills throughout Wales that are now included in a variety of hill list categories.

We endeavour to use best available data on any given day for our Welsh Highlands list.  By doing so we believe it enables our list to be as up-to-date as possible, even if a hill may be included one day and then excluded a month later due to continued terra-forming removing it from qualifying existence.  The main qualifying factor outside of the relevant numerical criteria is that the hill is considered solid and stable.  A good test for this is to jump up and down on its summit, if it does not move then it passes the test.  However, in this case we could inspect from a distance.

We met at 7.00am in the Cae Clyd car park at Manod on the outskirts of Blaenau Ffestiniog.  The forecast was for sunny conditions with the possibility of a rogue shower materialising in the afternoon.  At this time in the morning we could have been excused for not believing this, as the cloud base was low obstructing all near hills. 

An old gate leading us on the footpath toward the hill

The cloud at least kept the temperature pleasant as we made our way to the end of the paved road and then continued on a track toward a public footpath.  This was the first time I had approached these hills from this direction and as we gained height the cloud rose with us, it seemed our timing was perfect. 

Misty early morning

Our route took us to Llyn y Manod.  In years gone by there was a fishing hut beside this lake, any vestige of this or its remains were out of view today as the mist still skimmed the land beside the lake as we approached. 

Llyn y Manod with Manod Bach rising above

From the lake an old quarry track leads up the western slopes of Manod Mawr which loomed above us as a great bulk of a hill.  This track meets the disused incline leading from the quarry down toward Blaenau Ffestiniog.  From here it was only a short walk to where the main quarry road emerged out of the still rising mist. 

Nearing the quarry road

At the intersection of the quarry road leading up toward the high point of our potential new hill the public footpath diverts around to its south and east.  This then climbs to meet the easterly slopes of the adjacent 658m map heighted hill.  From here we looked down on our potential new hill which has a quarry road passing over its summit area.  Because of this we knew that it was solid and stable. 

The intersection between the quarry road and the public footpath

On the summit of the 658m map heighted hill we met the only other person we saw on the hill all day.  He told us he had Covid and advised we keep our distance, when doing so I was standing downwind of him; I soon changed my position and thanked him for telling me so. 

Looking down on Chwarel Graig Ddu

We then Abneyed the summit of this hill and decided to gather data from the highest ground visible at the base of the large summit cairn.  The view from this summit is extensive and as my last visit to this hill was in March 2004 it was good to be back after a gap of 18 years. 

Approaching the high point of the day

To our west we watched as darkened cloud edged its way northward toward the high Glyderau and Carneddau.  It was now early afternoon and the cloud was thickening and even though threatening darkened cloud occasionally built up over the tops we visited, it remained dry, which for our purposes on the hill was welcome. 

Gathering data at the summit of Pt. 658.45m (SH 727 458)

We now had four potential sub hills to survey, the first of which was only a short distance below us.  I had surveyed this first small prominence hill with a basic levelling staff in August 1998 and the other three in October 2005, and Aled had compared my results to his interpolation of the 5m contouring available online.  With the aid of the Trimble GeoXH 6000 we could now put accurate heights and positions to each of these four hills.

One of the joys of surveying is the places such a pastime takes you to, and these potential sub hills did just that, as the land hereabouts is probably seldom visited.  But today it was quiet with light and shade across the landscape adding depth to perspective, with each hill in turn giving extensive and rewarding views.

After surveying the first potential sub we followed the line of a fence down steep ground to where a complicated series of summits and bylchau are placed.  Our three remaining hills where positioned relatively close to each other and therefore surveys came thick and fast. 

Gathering data at the summit of the third of four potential sub hills

Moel Penamnen

The summit of our penultimate hill gave views across Llyn Bowydd and Llyn Newydd to the shapely profile of Moel Penamnen.  This was our furthest northerly point during the day; from here we headed south surveying another potential sub on our way. 

Looking out toward Cnicht

Beside Llyn y Manod

From the summit of our last potential sub hill all that remained was the walk out aiming for the eastern shore of Llyn Du Bach, which connected us with a path leading toward the incline heading down from the higher tops toward the outskirts of Blaenau Ffestiniog.  We crossed this and made steady progress up to the earthen track leading to Llyn y Manod.  As we gained the track we rested, which for me was a welcome break. 

Late afternoon light

Manod Bach

Our remaining route followed the path on the eastern shore of the lake before joining our inward route from earlier in the day.  The atmospheric misted scene from early morning had long been replaced by blue skies, late afternoon warmth, extensive views and the knowledge that the main aim of the day had been completed. 

 

Survey Result: 

 

Chwarel Graig Ddu

Summit Height:  613m

Summit Grid Reference:  SH 72505 45533

Bwlch Height:  592m

Bwlch Grid Reference:  SH 72456 45744

Drop:  21m (Uchaf addition) (600m Sub-Twmpau addition)

Dominance:  3.43%

 

 

Pt. 658.45m

Summit Height:  658.45m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 72741 45844 (Trimble GeoXH 6000)

Bwlch Height:  c 593m (interpolation)

Bwlch Grid Reference:  SH 72943 45510 (interpolation)

Drop:  c 65m (Trimble GeoXH 6000 summit and interpolated bwlch)

Dominance:  9.94% (Trimble GeoXH 6000 summit and interpolated bwlch)

 

 

Pt. 643.1m

Summit Height:  643.1m (converted to OSGM15)

Summit Grid Reference:  SH 72780 46053

Bwlch Height:  633.0m (converted to OSGM15)

Bwlch Grid Reference:  SH 72816 46026

Drop:  10.1m

Dominance:  1.57%

 

 

Pt. 535.0m

Summit Height:  535.0m (converted to OSGM15)

Summit Grid Reference:  SH 72348 46195

Bwlch Height:  524.3m (converted to OSGM15)

Bwlch Grid Reference:  SH 72392 46231

Drop:  10.8m

Dominance:  2.01%

 

 

Pt. 516.9m

Summit Height:  516.9m (converted to OSGM15)

Summit Grid Reference:  SH 72414 46598

Bwlch Height:  507.0m (converted to OSGM15)

Bwlch Grid Reference:  SH 72346 46467

Drop:  9.9m

Dominance:  1.92%

 

 

Pt. 519.2m

Summit Height:  519.2m (converted to OSGM15)

Summit Grid Reference:  SH 72188 46369

Bwlch Height:  509.6m (converted to OSGM15)

Bwlch Grid Reference:  SH 72312 46434

Drop:  9.6m

Dominance:  1.85%

 

 

For further details please consult the Trimble Survey Spreadsheet

  

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