Mapping Mountains – Trimble Surveys – Moel Hebog

07.10.23  Pt. 576.0m (SH 559 475) 

Pt. 576.0m (SH 559 475) (Photo: Aled Williams)

I am fortunate to be in a position that I can choose which day to head to the hills, and therefore rarely venture out when conditions are not favourable, especially when it is misty and raining.  However, with only three hills remaining to complete the listing of the Welsh Highlands – Uchafion Cymru, even unfavourable conditions can get the better of one’s mentality and drag you out to the hill.

By 7.00am I was parked on Aled’s drive in Porthmadog and transferring my gear in to his car.  Overhead the hills were blanketed in low cloud and mist, with flecks of wind-blown drizzle adding bleakness to the prospect of venturing out on any hill.  Twenty minutes later and we were at the end of Cwm Pennant having found a convenient parking place just off the minor road close to the last farm in the valley.

As I stood beside the car I was not enthusiastic to head up in to the murk and suggested we could go back to Aled’s for a cuppa and chat, all he had to do was smile and agree and the day on the hill would have been postponed.  But, having driven up the valley he was enthusiastic for us to continue, and after a bit of internal grumbling I agreed.

The hill we were heading for is positioned between Moel Hebog and Moel yr Ogof.  I had passed its summit on numerous occasions but until today never visited.  It is spectacularly positioned above a natural cleft in rock, and overlooks a large pool that constitutes the bwlch connecting with Moel yr Ogof and has excellent distant views up to its higher immediate neighbours and across to Yr Wyddfa.  Today I’m afraid none of this was on show.

Leaving the car we headed toward the first stile of the day and followed a path forever heading up toward Bwlch Meillionen.  We were soon in the murk, with the morning’s drizzle intermittent.  Usually keeping to a path is easy in the mist as there is little else to visually concentrate on, however Aled wanted to examine some of the rock outcrops higher up, therefore we kept the Afon Cwm-llefrith close at hand on our right and ventured away from what is a good quad bike track that we followed after the summit adventure on our descent back out of the gloom.

When high on the hill we spent about 30 minutes pottering around rocky ground investigating various outcrops before joining a sheep path that took us toward the bwlch on the Moel Hebog side of it.  It was now decidedly blowie with the wind picking up the higher we ventured.  Even though the visibility was limited it felt good to be back here after so many years, and even though we were only going to be on the section between the higher 2,000ft peaks for a short time and not visit their summits, it was still thrilling to be so high.  We now headed left and walked down to the bwlch and then steeply up toward the cleft in the rock that gives passage toward the summit of Moel yr Ogof. 

Heading up toward the cleft in the rock

At the top of the cleft we headed left, clambered over a stone wall and gained steepening runnels of grass interspersed amongst rock that took us up toward the summit of the one hill of the day.  I waited on grass as Aled headed over to the high point, hunkering down as he neared the summit as the wind was whipping across the hill.  When he arrived back at my position he advised me to be careful and suggested I leave my rucksack on the grass before heading up to stand on the summit.  Rather foolishly I did not adhere to his advice and headed up on the rock.

The next few minutes are a bit of a blur.  The rock was wet and very greasy.  I remember being ever so careful with each foot placement, making sure that each step was on relatively flat rock and wriggling my foot on it to make sure of a firm placement before transferring my weight and gaining further progress.  The summit of this hill comprises a small rocky ridge with a sheer drop on its northern side down in to the depths of the cleft of rock that we had just walked up.  Its opposing side comprised slanting rock forever falling away down on its southern side.  It reminded me of a small Knight’s Peak in the Cuillin on Skye.

I was now within about 2ft of its high point and about 4 inches below it and the next thing I can remember is seeing rock shooting past my eyes as I slithered down the southern side of the hill.  I have no memory of slipping, just a feeling of near rock and wanting to stop my fall.  I suspect in such circumstances survival instinct kicks in and I remember clinging on to rock with my right hand and trying to wedge me feet in to any flat ground below my body.  At the very moment I stopped, Aled had jumped from his position on the grass, grabbing me as he did so.

The next five minutes I stood on the grass recovering as Aled kindly put a plaster on my right little finger which was bloodied.  I had grazed and scraped my left lower leg and left buttock, bruised my right upper thigh and my back behind my right shoulder.  Thankfully I did not slither very far, as even on this southern side the continuation down the rock was not welcoming.  I didn’t talk for a number of minutes as I suspect the shock of the situation had kicked in.  After partly recovering I headed back up, this time keeping below the small ridge, touching its high point with my hand and then hooking my right leg up so my foot at least also touched the high point, and then slowly made my way down to re-join Aled who waited on the safety of the small patch of grass. 

At the summit, just after slipping down it! (Photo: Aled Williams)

I was still aware that I was not saying much as we clambered back over the wall.  I then headed down the steep ground and waited in the cleft between the rock walls out of the wind as Aled headed over to visit an adjoining sub.  By the time he arrived back at the cleft I was in chatty mode.  I had also had time to examine my various grazes and what no doubt will be impressive bruising in a day of two.  

As suspected, my right thigh came out in a good bruise a couple of days later 

Standing there on my own waiting for Aled also gave me time to ponder how fortunate I had been as I was standing on a narrow ridge of rock in wind, with underfoot conditions particularly slippery and the thought of what would have happened if I had fallen on the northern side of the ridge is not very comforting as I would have gone over a sheer drop down in to the cleft.  The thought of this kept me awake for the following night as I closed my eyes and had horrible images of dropping in to mist enshrouded oblivion.  Thankfully I survived to see another day, and my thanks to Aled for grabbing me just as I had halted and being attentive after the event. 

Out of the murk heading toward the relative safety of the valley below

The onward journey was not as exciting as the summit adventure, but was much safer as we followed the quad bike track down from the bwlch through a series of gates and over stiles.  The underfoot conditions were particularly wet, but the path gave passage toward the safely of the car in the valley below.  Third to last hill survived, just another two to go. 

 

Survey Result:

 

Pt. 576.0m                                

Summit Height:  576.0m (LIDAR)

Summit Grid Reference:  SH 55928 47521 (LIDAR)

Bwlch Height:  560.4m (LIDAR)

Bwlch Grid Reference:  SH 55885 47595 (LIDAR)

Drop:  15.6m (LIDAR) (Welsh Highland Sub addition) (Welsh Highland Sub reclassified to Welsh Highland P15)

Dominance:  2.70% (LIDAR)

 

 

For further details please consult the Trimble Survey Spreadsheet

  

Mapping Mountains – Trimble Surveys – Moel Hebog

10.12.22  Ynys Tywyn (SH 571 385) 

Ynys Tywyn (SH 571 385)

Ynys Tywyn is easily accessed from the centre of Porthmadog, it is one of those small hills that pays dividends, with little ascent being rewarded with extensive views.  I had visited once before in December 2014 when along with Aled we decided upon an easy hill as the forecast winter rain was bearing down on us.  On that occasion its summit was Trimbled.

That ascent was part of many that Aled had organised as we continued our investigation of Traeth Mawr; the flatlands to the immediate east of the Cob.  The Cob is the embankment built on the outskirts of Porthmadog to keep the sea from heading inland at high tide.  When it did so, the islands of Traeth Mawr must have been a wonderful sight, poking their wooded summits above the sea.  These now landlocked islands can still be accessed, although many are rough underfoot, but they are also rewarding to investigate. 

Plaque on wall at the start of the walk

Today we were in the company of a film crew from the Cynefin programme which is broadcast on S4C.  They were concentrating on the area surrounding Porthmadog and in particular the Cob.  They had approached Aled to be a part of this programme having found his article on Traeth Mawr published on Mapping Mountains, suggesting that a visit to one of these islands with the Trimble in tow would be good to film.

I drove to Aled’s and arrived at 7.10am having experienced slow progress on much of the route due to a dusting of snow on the road.  The journey was particularly beautiful as moonlight highlighted silhouetted hills that shone back under their covering of snow. 

Aled with the film crew from the Cynefin programme on S4C; Heledd Cynwal, Aled Davies-Jones, Lleucu Gruffydd and Rhys Thomas

We met Lleucu and Heledd; the producer and presenter in the centre of Porthmadog before having an early morning paned.  Afterwards we were joined by Aled and Rhys; the director/cameraman and cameraman respectively.  By now a mixture of winter rain and occasion hail was descending from above.

The walk to the top of Ynys Tywyn is only short, following a path through its wooded slopes to the impressive slanting rock that constitutes its summit.  The upper part of the hill had a sprinkling of frost on it adding winter colour to the scene.

It is not my intention to go in to any great detail of the filming in this article as a future On Location with S4C post will document this.  We stayed on top for almost two hours with Aled being filmed explaining the process behind using an Abney level and the Trimble. 

Porthmadog with winter showers pushing inland from the coast

During this I happily listened to the proceedings from the background enjoying being out on this small island, which nowadays is connected to the town of Porthmadog by the Cob.  I spent much of the time watching the play of light as winter showers pushed inland from the coast.

In the distance snow-capped peaks occasionally emerged from their winter shroud, with the upper part of Cnicht springing out of the grey misted scene with its pyramidal summit profile looking ever impressive.  However, many hills were obscured with deep grey cloud penetrating their depths. 

Snow-capped hills

For a relatively small hill Ynys Tywyn certainly has a dramatic and expansive view.  The workings of the film crew would occasionally be interrupted by the hoot emanating from the steam train as it chugged its way across the Cob, bellowing smoke across the harbour surrounds. 

At the summit of Ynys Tywyn with Aled explaining the fineries of the Trimble

The last shots were of Aled explaining the fineries of the Trimble and then it was time to head down.  For Aled the filming would go on for the rest of the day, but for me it was time to head home before the roads froze and darkness fell. 

 

Survey Result: 

 

Ynys Tywyn 

Summit Height:  21.8m (converted to OSGM15) (from previous Trimble GeoXH 6000 survey)

Summit Grid Reference:  SH 57192 38506 (from previous Trimble GeoXH 6000 survey)

Bwlch Height:  N/A (sea level)

Bwlch Grid Reference:  N/A (sea level)

Drop:  21.8m (from previous Trimble GeoXH 6000 survey) (30–99m Double Sub-Twmpau addition)

Dominance:  100.00% (from previous Trimble GeoXH 6000 survey)

 

 

For details on the survey of Ynys Tywyn

For further details please consult the Trimble Survey Spreadsheet   

  

Mapping Mountains – Trimble Surveys – Moel Hebog

 

10.04.21  Graig Goch (SH 496 485), Graig Goch (SH 495 484), Graig Goch (SH 497 485), Mynydd Graig Goch (SH 497 485), Graig Goch (SH 498 483), Garnedd Goch (SH 511 495) and Pt. 733.4m (SH 525 502) 

Garnedd Goch (SH 511 495)

Since getting the Trimble there are few places that I’ve wanted to survey more than the hills that comprise the Nantlle ridge.  In the past these hills dominated many of my weekends as my mother lived in Nantlle.  When visiting I would open the skylight at night in the converted attic bedroom, let my eyes become accustomed to the dark and then follow the ridge line from the upper part of Garnedd Goch to the ground above Craig Cwm Silyn.  On moonlit nights these hills sparkled with their crags plummeting to the darkened moorland and grazing fields below. 

The Nantlle ridge is one of the walking highlights of Wales.  It beckons with many a subline hill profile.  Many years ago I took every opportunity to visit, the majority of which were two car linear walks; either with a friend to accompany me doing the ridge or with someone to drop me off at one end of it.  These were the days before Mynydd Graig Goch was declared a 2,000ft mountain, this ‘news’ still entertains many of the locals. 

When the survey result of Mynydd Graig Goch hit the headlines I proceeded to visit its high point each month until my monthly round total matched the other 2,000ft Welsh hills, this entailed 16 ascents.  I’d set off usually from the parking area close to the high mast that dominates the skyline to the north-west of the hill.  Occasionally I investigated the paths leading up the hill via its bwlch connecting it with Garnedd Goch. The hill never disappoints; its summit tors are marvellous to either walk or scramble up.  The hill is also the last 2,000fter in Wales before the Llŷn heads westward.  Mynydd Graig Goch is a fine hill and I hadn’t visited it for 12 years.  Neglecting such a hill can also enthuse to re-visit and when this hill and its many tors were suggested for a surveying expedition I was easily tempted. 

The person doing the tempting was Aled who wanted one particular tor surveyed.  Mark joined us for the day and by around 10.30am we were parked and walking up the track leading toward Llyn Cwm Dulyn.  As both Aled and Mark are quicker than me, I set off before them slowly gaining height on the path that heads up from the track leading to the lake.  This was the same path that we used when originally surveying Mynydd Graig Goch in 2009.  Then the weather deteriorated and proved positively vile on the summit, where we hunkered down for over two hours as James Whitworth’s Leica equipment gathered the all-important summit data. 

Garnedd Goch rising above Llyn Cwm Dulyn

Today the forecast gave mainly dry conditions with the prospect of wintery showers in the afternoon brought on by a chilled northerly breeze.  As I made steady progress up the well-defined path I occasionally glanced backward and although other people were using the same path there was no sign of Aled or Mark. 

By the time I neared the upper rocky part of the hill I had two pairs of gloves, an ear warmer and fleece balaclava on as the northerly breeze was wind-like.  However, the ridge was clear as indeed were all near hills.  It was a sheer joy to be back on this hill, its tors brought back so many memories, the people with me and the reasoning for repeating visits, all add to the varied texture of memory, the company shared and the weather conditions encountered, even that chilled two hour wait for data to be gathered when I ended up shivering and soaked through, this still brings a smile to my face when I think of it. 

The first tor I reached was the one I thought Aled wanted surveying.  Its high point consisted of a flake of rock.  I positioned the Trimble with its internal antenna aligned with the high point and then wedged it in place with a number of rocks.  By the time five minutes of data were gathered and stored I was joined by Aled, who looked at me and asked why I was surveying this tor, when I replied that I thought this was the one he wanted surveying, he laughed and pointed down to our south-west where a lower but more prominent tor was positioned.  I laughed back at him, but as the summit of this first tor had been surveyed we decided to do likewise for all the other major tors on the hill. 

Gathering data at the first rock tor - Graig Goch (SH 496 485)

As the Trimble was packed away Mark emerged with a broad grin on his face and was soon standing in celebratory fashion beside the flag pole that now adorns this tor.  The second rock tor we surveyed is impressive, we collected data from its connecting bwlch and summit during which Aled and Mark hunkered down out of the chilled northerly wind and I stood an appropriate distance away from the equipment so as not to get in the way of satellite reception and waited for the allotted data to be gathered and stored. 

Gathering data at the second rock tor - Graig Goch (SH 495 484)

Between the second tor and the high point of Mynydd Graig Goch is another tor of similar, but importantly slightly lower height.  This was surveyed with the Leica Smartrover in 2009 and also proved to break through the magical 609.6m / 2,000ft benchmark height.  The same tor was now surveyed with the Trimble GeoXH 6000. 

Gathering data at the third rock tor - Graig Goch (SH 497 485)

The next tor on our continuing surveying agenda was the pinnacle of rock that constitutes the summit of Mynydd Graig Goch.  To my knowledge this is the first time this point has been surveyed since the Leica equipment was strapped to its side.  Then just over two hours of data were gathered, today it was six minutes. 

The Leica SmartRover gathering data at the summit of Mynydd Graig Goch

During data collection I stood below the equipment looking out toward Garnedd Goch as it rose skyward with its impressively built wall framing its south-westerly flank.  Shadows danced across near hills, whilst others sank in shade with their profiles rearing skyward.  This part of Wales as with many others is always special as valley and hill meet in usually dramatic fashion. 

Gathering data at the fourth rock tor - Mynydd Graig Goch (SH 497 485)

Garnedd Goch with the snow-capped Yr Wyddfa and Y Lliwedd in the background

Once the Trimble was closed down we had one last remaining tor to visit and survey, this had its bwlch and summit Trimbled before we headed down to the path across the moor that heads for the connecting bwlch between Mynydd Graig Goch and Garnedd Goch. 

Gathering data at the fifth rock tor - Graig Goch (SH 498 483)

Reaching the bwlch we said our goodbye’s to Mark as he wanted to visit the Pedwar of Ffridd Arw Uchaf and that would entail repositioning his car.  This left Aled and I to survey the bwlch of Mynydd Graig Goch which proved one of the easiest to identify as it was tight on both the hill to hill and the valley to valley traverse.  Once the allotted data were gathered and stored I followed Aled on the same path that Mark was now descending, toward the connecting wall that heads up to the summit of Garnedd Goch. 

Heading toward the bwlch of Mynydd Graig Goch

Gathering data at the bwlch of Mynydd Graig Goch

I rested a few times heading up beside the wall but made steady progress.  Eventually the remains of the weather battered trig pillar came in to view as did the large ancient cairn that now incorporates the summit of this hill.  When I joined Aled at the summit we debated where data should be gathered.  There were two large rocks below the trig pillar, but as other smaller rocks were higher and these seemed solid enough we decided that as they had been there an inordinate amount of time they could be deemed as being a part of this hill’s summit. 

Gathering data at the summit of Garnedd Goch

From the summit of Garnedd Goch the view opens to the high Eryri peaks with Yr Wyddfa still snow-capped and looking forever inviting with its great ridges curving around its higher domain.  It always entices from this view and more so from the highest point of the Nantlle ridge which was now ahead of us. 

Yr Wydfa from Garnedd Goch

Between us and this high point was the connecting bwlch of Garnedd Goch and we were soon there assessing where its critical point lay.  Its whereabouts was not too difficult to pinpoint and soon the Trimble was set up quietly beeping away gathering its all-important data. 

Gathering data at the bwlch of Garnedd Goch

Just the last major uphill of the day remained; toward the high point of the Nantlle ridge.  This is given as Craig Cwm Silyn in many hill lists, however this name is strictly applicable to its northerly cliff face and not to the hill itself, as this is known locally by a different name which, for now, is being kept back, so the hill is being listed by the point notation. 

Approaching the high point of the Nantlle ridge

The summit of this hill is positioned in its wind shelter where two small embedded rocks vie for its high point.  Having chosen our preferred highest I set the Trimble up on top of my rucksack to give it elevation above its immediate surrounds, measured the offset between its internal antenna and the ground at its base and waited for the 0.1m accuracy level to be attained before data should be logged.  Once this figure appeared on the screen I pressed ‘Log’ and joined Aled sitting on a part of the tumbled rock making up the wind shelter as the allotted data were gathered and stored. 

Gathering data at the summit of Pt. 733.4m (SH 525 502)

This summit affords one of the best views anywhere in Wales with Yr Wyddfa as backdrop and the slender grassed ridge leading from Mynydd Tal y Mignedd to Trum y Ddysgl as foreground, with the latter seemingly suspended in motion.  Similar to a painted picture hung and admired, this view never disappoints. 

One of the best views in Wales

All that remained was to devise a route off the hill and I left Aled to do that.  I happily followed as we looked down the steep crags of a part of Craig Cwm Silyn as our path slithered across its top.  Beyond this we encountered rough ground, leaving the path to cross the wall that makes its way up Garnedd Goch from its north-west.  The rough ground continued beyond with tough moor grass and hidden rocks and it did not make for a quick descent although it felt as if we sped across it. 

Heading down

Down we went and eventually connected with the path that leads upward to the bwlch where Mark had left us.  This now gave favourable underfoot conditions giving relatively easy going and led us to the outflow of Llyn Cwm Dulyn where a footbridge joined with our mornings inward track.  The last hour or so had given beautiful colour with the hills starting to glow in early evening light.  It was a fitting end to a magical day on the hill. 

 

Postscript 

Since visiting these hills full LIDAR coverage is now available.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height and positional data that is now freely available for England and Wales.  Consequently the numerical details for these hills have been analysed using this technique, resulting in the LIDAR height and position being used for some of these hills.

 

Survey Result: 

 

Graig Goch

Summit Height:  607.4m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 49645 48570 (Trimble GeoXH 6000) 

Bwlch Height:  c 603m (interpolation)

Bwlch Grid Reference:  SH 49671 48586 (interpolation)

Drop:  c 4m (Trimble GeoXH 6000 summit and interpolated bwlch)

Dominance:  0.72% (Trimble GeoXH 6000 summit and interpolated bwlch)

 

 

Graig Goch

Summit Height:  597.9m (converted to OSGM15)

Summit Grid Reference:  SH 49522 48444   

Bwlch Height:  585.9m (converted to OSGM15)

Bwlch Grid Reference:  SH 49541 48497

Drop:  12.0m

Dominance: 2.01%

 

 

Graig Goch

Summit Height:  609.6m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 49707 48555 (Trimble GeoXH 6000) 

Bwlch Height:  606.3m (LIDAR)

Bwlch Grid Reference:  SH 49717 48534 (LIDAR)

Drop:  3.3m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  0.54% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

Mynydd Graig Goch

Summit Height:  609.8m (converted to OSGM15, Trimble GeoXH 6000) 609.8m (converted to OSGM15, Leica SmartRover 1200)

Summit Grid Reference:  SH 49729 48515 (Trimble GeoXH 6000) SH 49729 48515 (Leica SmartRover 1200)    

Bwlch Height:  535.9m (converted to OSGM15)

Bwlch Grid Reference:  SH 50929 48808

Drop:  73.8m (Trimble GeoXH 6000) 73.9m (Leica SmartRover 1200 summit and Trimble GeoXH 6000 bwlch)

Dominance: 12.11% (Trimble GeoXH 6000) 12.11% (Leica SmartRover 1200 summit and Trimble GeoXH 6000 bwlch)

 

 

 

Graig Goch

Summit Height:  607.35m (converted to OSGM15)

Summit Grid Reference:  SH 49877 48393   

Bwlch Height:  599.8m (converted to OSGM15)

Bwlch Grid Reference:  SH 49858 48418

Drop:  7.6m

Dominance:  1.24%

 

 

Garnedd Goch

Summit Height:  701.9m (converted to OSGM15)

Summit Grid Reference:  SH 51114 49522   

Bwlch Height:  676.8m (converted to OSGM15)

Bwlch Grid Reference:  SH 51908 49970

Drop:  25.1m

Dominance: 3.58%

 

 

Pt. 733.4m

Summit Height:  733.4m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 52555 50262 (Trimble GeoXH 6000)   

Bwlch Height:  334.9m (LIDAR)

Bwlch Grid Reference:  SH 55308 49663 (LIDAR)

Drop:  398.5m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance: 54.34% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Trimble Surveys – Moel Hebog

08.04.18  Pt. 532.7m (SH 574 441), Moel Ddu (SH 579 441), Moel Ddu (SH 579 442) and Mynydd Gorllwyn (SH 585 427)

Moel Ddu (SH 579 442)

Today’s walk proved a good circuit of hills above Llyn Cwmystradllyn in the company of Mark and Aled, with the main surveying objective being a 534m map heighted hill that I had surveyed in May 2000 using a basic levelling technique as having 29.1m of drop.  This we planned on combining with the two higher Moel Ddu summits and the 239m map heighted Mynydd Gorllwyn as our last hill.

The early morning low cloud had risen by the time we set off walking around the western side of the lake, following an old track past forgotten and derelict farmsteads whose robust lower walls still stand firm.

Mark and Aled on the track leading to the Gorseddau Quarry

Although the forecast was good there was still a winter feel to the land with bare trees and fawn coloured reed grass enclosing the adjacent fields.  Passing the old Plas-llyn and its shielding copse of trees, moss predominated on the lower bark and root, a sign of damp and the passage of time.

Moss on trees

Ahead lay the remains of the Gorseddau Quarry with the lofty heights of Bryn Bannog above, one merging in to the other.  We stopped for a bite to eat close to a quarry wall that would not be out of place in the stone work of the Inca.  Here I de-layered as sun broke through high cloud and the warmth of spring gave a welcoming feel.

Bryn Bannog and the Gorseddau Quarry

This wall wouldn't be out of place in Cusco

Moel Hebog

The first point to survey was a short distance above and consisted of a large, flat looking bog, this is the bwlch area of Moel Ddu, and I sloshed about in its unsavoury depths for a few minutes trying to find where the most appropriate placement was to take the data set, during this Aled and Mark stood on a raised hummock of dry land directing me one way and the other, I eventually opted for land close to the stone wall that crosses the bwlch.

Gathering data at the bwlch area of Moel Ddu

The upper part of Moel Ddu now dominated the horizon, this is a fine hill set back from its higher neighbours and we had about 200m to gain in height before standing on its summit, and most of this uphill proved rather steep.

Moel Hebog and the Gorseddau Quarry

The ascent toward the Moel Ddu ridge

Nearing the ridge connecting to Moel Ddu we had options for which summit to visit first and decided to head for the hill that I had surveyed 18 years ago.  This hill has two tops vying for its high point, and both were Trimbled.  During this the waters of Llyn Cwmystradllyn nestled in the high valley below and reflected sky and cloud.

Gathering data at the first of two surveys for the summit position of Pt. 532.7m

Llyn Cwmystradllyn

The second top surveyed for summit position has a large flat rock on its high point and the merit of including this in the measurement of the hill was debated at length as when standing on it, it wobbles.

Gathering data at the second of two surveys for the summit position of Pt. 532.7m

The next surveying objective was the connecting bwlch of this hill and as Mark and Aled soaked in the sunshine and view, I headed down toward the bwlch and used the ten figure grid reference produced by LIDAR analysis for positioning of the Trimble atop my rucksack, and once the measurement offset was taken between its internal antenna and the ground below, I waited for the 0.1m accuracy level before data should be gathered and then pressed ‘Log’ and waited for the allotted data points to be collected and stored.  Next stop the summit of the southern top of Moel Ddu.

Gathering data at the critical bwlch of Pt. 532.7m

This hill had also been surveyed using a basic levelling technique in May 2005 and today with Aled’s assistance the Trimble was positioned rather precariously on a balanced rock on the edge of the summit cairn, with an offset taken to the highest part we could find of the large rock that sits below the cairn.

The two Moel Ddu summits

As the Trimble beeped away gathering another data set Mark and then Aled headed over to the higher summit of Moel Ddu, and once the Trimble had done its stuff I joined them.

Gathering data at the summit of Moel Ddu (SH 57911 44136)

By now threatening dark grey cloud was massing to the east with the peaks of the Arenig immersed in what was no doubt heavy rain, thankfully we were still in sunshine but we wondered if the rain would edge our way.

The Trimble was positioned a few metres from the base of the large cairn atop the higher of the Moel Ddu summits on ground that the three of us judged was higher than that at the immediate base of the cairn.  As data were gathered the dark grey cloud began its slow path westward toward the high Moelwynion which were now bathed in threatening grey.

Gathering data at the summit of Moel Ddu (SH 57958 44205)

To our north the hills of Yr Wyddfa were also bathed in the mass of grey cloud as indeed was Cnicht, with light and shade giving depth to the land, and yet we remained in sunshine.

Dark clouds massing

Cnicht

Before leaving the confines of Moel Ddu I wanted to survey the connecting bwlch between the two summits, this was on moor grass away from the high stone wall that passes over the bwlch and also away from the steepening slopes of the lower summit.

Gathering data at the area of the bwlch of the lower of the two Moel Ddu summits

We had one hill remaining to visit; Mynydd Gorllwyn which was southward from where we now were and entailed loosing height down toward land to the north of its bwlch.  The bwlch looked another boggy affair and its survey could wait until after the summit.

Mynydd Gorllwyn

Mynydd Gorllwyn is a fine hill, sunbathed as it was when we visited with rain showers to its south across the northern Rhinogydd, it dazzled in the sun invitingly and we headed toward its north-western slopes on a semblance of green land away from the fawned land of tussocks that pre-dominated the hill.

Cnicht

Cnicht and Moelwyn Mawr

Storm clouds massing over the Moelwynion

The going to the summit proved tough at the end of a long day on the hill with heat and steep ground proving wearisome, but soon the high point came in to view and as we sat and soaked in the land to our south that plunged down to the valley below, the Trimble beeped away gathering its last summit data set of the day.

Striking light on Moel Ddu

Gathering data at the summit of Mynydd Gorllwyn

All that remained was the connecting bwlch and this was in a land infested with high tussock grass that few must venture to.  As I remained with the Trimble, Aled and then Mark headed up to a track that would in time lead us back to my car.  However, I waited at the bwlch resting beside a fence until the last of the day’s data sets was stored and then slowly sweated my way up to the track to join them.

Nearing the end of another excellent day

The track headed southward as the grey mass of rain cloud edged northward away from us.  Arriving back at the car and getting my boots off was a delight, we were soon sitting in The Ring at Llanfrothen enjoying an evening meal and good conversation, a perfect way to end the day.

  

Postscript 

Since visiting these hills full LIDAR coverage is now available.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height and positional data that is now freely available for England and Wales.  Consequently the numerical details for these hills have been analysed using this technique, resulting in the LIDAR height and position being used for some of these hills.

Survey Result:

Pt. 532.7m

Summit Height:  532.7m (converted to OSGM15)

Summit Grid Reference:  SH 57455 44182

Bwlch Height:  503.9m (converted to OSGM15)

Bwlch Grid Reference:  SH 57647 44157

Drop:  28.9m 

Dominance:  5.42%

Moel Ddu

Summit Height:  550.1m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 57911 44136 (Trimble GeoXH 6000)

Bwlch Height:  535.6m (LIDAR)

Bwlch Grid Reference:  SH 57937 44167 (LIDAR)

Drop:  14.5m (Trimble GeoXH 6000 summit and LIDAR bwlch) 

Dominance:  2.63% (Trimble GeoXH 6000 summit and LIDAR bwlch)

Moel Ddu

Summit Height:  552.4m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 57958 44205 (Trimble GeoXH 6000)

Bwlch Height:  353.6m (LIDAR)

Bwlch Grid Reference:  SH 57528 44918 (LIDAR)

Drop:  198.8m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  35.98% (Trimble GeoXH 6000 summit and LIDAR bwlch)

Mynydd Gorllwyn

Summit Height:  239.3m (converted to OSGM15)

Summit Grid Reference:  SH 58519 42702

Bwlch Height:  197.9m (converted to OSGM15)

Bwlch Grid Reference:  SH 58095 42705

Drop:  41.4m

Dominance:  17.30%

For further details please consult the Trimble Survey Spreadsheet