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 – Moelwyn Mawr

 

22.09.21  Garth Ganol (SH 626 394) 

LIDAR image of Garth Ganol (SH 626 394)

Garth Ganol was the last of three hills we visited during the day.  Each were wooded, with the first; Bryn y Gwynt (SH 599 499) and this last hill being relatively easy walks compared to the brambled domain of the second hill; Cefn Coch (SH 610 396). 

These three hills proved an ideal way to salvage the day as the weather in the morning was particularly unwelcome, with low cloud and wet conditions in this part of Wales, which meant that our planned outing to Moel y Dyniewyd (SH 612 477) and it adjacent hills was shelved for a more favourable day. 

Garth Ganol forms a part of a small peninsula overlooking the Afon Dwyryd close to where it deposits its contents in to the sea.  Aled had previously approached this hill from the south-west and visited an intermediary top.  This approach was recommended but it would also give us a longer route through probable unsavoury undergrowth.  Therefore, we opted for the easy approach and drove up an unmarked paved road to just below the summit to its north. 

Before starting up the hill I asked permission at a house beside the road named Bryn Dwyryd, whether we could park the car beside a large barn a 100 or so metres from the house, with permission granted we eventually opted to park close to a gate which was off the paved section of road. 

Heading up through the wooded northerly slopes of the hill

The gate gave access in to woodland that forms a large part of this hill.  Above us were bee hives which we not surprisingly purposely avoided.  Once through the first gate, a dirt track led to another solid gate and from here I followed Aled as he weaved a way upward through the mature woodland to emerge out of the trees near the summit of the hill. 

Bracken, gorse and heather and the added bonus of a barb wired fence

We were now standing on a small intermediary top with the summit of the hill on the other side of a barb wired fence, between us and it was a good scattering of gorse.  Although prickly if wearing shorts; as I was, gorse is not problematic unless thick and high.  Thankfully the gorse we encountered on this hill was neither and we were soon on what looked to be the summit.  However, ground to our south-west needed investigating and I again followed Aled as he headed that way.  Once there we deemed it higher. 

Gathering data at the summit area of Garth Ganol

There were a number of points that vied for summit position, all a few metres apart and all of similar height, we chose the one we thought the highest and soon the Trimble was set up gathering data.  When back home I analysed this hill with LIDAR and this gives the Trimble set-up position approximately eight metres from the summit and as the height produced by LIDAR is 0.25m higher than the height produced by the Trimble GeoXH 6000 survey, it is the LIDAR data that is being used for listing purposes.  In our defence the summit identified by LIDAR looks to be positioned in a large outcrop of heather and gorse, with the natural ground below being extremely hard to distinguish in height compared to its near surrounds. 

Looking out toward the rough surrounds of the northern Rhinogydd and the Afon Dwyryd

We of course, were oblivious to the LIDAR summit position, but it is always good to get a comparison against data produced by the Trimble GeoXH 6000.  During data collection I stood and admired the view south-eastward across to the rough slopes forming a part of the northern Rhinogydd and eastward down the near estuary of the Afon Dwyryd.  It felt good to be on an open summit after the confines of the two previously visited wooded hills. 

Heading down with the higher cloud enshrouded Moelwynion in the background

Once data were gathered and stored we reversed our inward route, back to and then over the barb wired fence and down through the wood to the awaiting car.  It had been another excellent day with three hills visited, in good company with good conversation, a meal sitting outside a café in Llanfrothen, and a panad or two along the way! 

 

Survey Result: 

 

Garth Ganol (significant name change)

Summit Height:  75.6m (LIDAR)

Summit Grid Reference:  SH 62600 39430 (LIDAR)

Bwlch Height:  27.7m (LIDAR)

Bwlch Grid Reference:  SH 62671 40069 (LIDAR)

Drop:  47.8m (LIDAR)

Dominance:  63.30% (LIDAR)

 

 

For further details please consult the Trimble Survey Spreadsheet

 

 

 

Mapping Mountains – Trimble Surveys – Moelwyn Mawr

 

22.09.21  Cefn Coch (SH 610 396) 

LIDAR image of Cefn Coch (SH 610 396)

Sometimes a walk can take on a surreal aspect where one part is in utter contrast to another.  This hill was such an example.  Cefn Coch; with the name appearing on the Ordnance Survey One-Inch ‘Old Series’ map, is positioned above the town of Penrhyndeudraeth and is one of many similar hills in this area that qualify for P30 status that are both wooded, rocky and seemingly pathless. 

We had hoped to visit Moel y Dyniewyd (SH 612 477), but low cloud and rain meant our plans were quickly rearranged.  The weather conditions dictated lower summits and Aled suggested visiting three hills, with Cefn Coch the second, all of them wooded, which would at least shelter us from any continuing drizzled rain.  However, this also meant that I had not come prepared with the ten figure grid references for each hill. 

Moel y Dyniewyd (SH 612 477)

We approached Cefn Coch from the east having parked in a large lay-bi on the A4085 road just below its connecting bwlch.  We walked up the road to where a public footpath sign confidently pointed toward the direction of the hill.  This we followed and then started to gain height giving views across Traeth Mawr to the higher Eryri peaks. 

The Yr Wyddfa massif was still cloaked in cloud as were the higher Moelwynion, but Cnicht stared back at us, standing out with its shapely profile easily identified.  Across the intervening flatlands Moel Ddu stood out with a cloud enshrouded Moel Hebog beyond.  From where we now were this view was to be savoured and more so as earlier in the morning the gloom was almost down to road level. 

The view of the Yr Wyddfa massif before the brambles overwelmed us!

This view was at contrast to what we found the higher up the hill we went.  Online logs gave a foretaste of the undergrowth encountered, with numerous visits finding a pathless morass of brambles. 

I followed Aled as he negotiated a way upward, initially a path of sorts made its way through bracken, but this soon lost interest and disappeared when the first brambles made their entrance.  Soon afterward we encountered a wall which was easily negotiated.  On the other side more bracken and brambles led to a rock outcrop which we slithered up and over.  More brambles emerged beyond! 

We reached a point that could have been the summit, but before setting the Trimble up, Aled investigated farther on and soon called me to join him as he was standing on higher ground.  Not satisfied with this position he again investigated farther in to the mass of undergrowth and reached a point that looked as if it was the summit.  Without a ten figure grid reference for the high point we were unaware that we were still 100 metres or so from the true summit.  By now my legs had been torn to pieces with bloodied scratches making a patchwork of patterns. 

The point we were now at consisted of a large mossed rock and soon the Trimble was set up gathering data.  During data collection we sat below the equipment and debated the fineries of what constitutes a published hill list.  This subject has direct relevance to a project we are currently working on, so time now permitted that we could discuss the details at length. 

Gathering data at the point we thought the summit

Once allotted data were gathered and stored I closed the equipment down, packed it away and followed Aled through the jungle of brambles and down the slithery rock to finally emerge back on the public footpath.  It was only a short walk from here to the awaiting car. 

Back through the jungle of brambles

When back home I processed the data and checked the co-ordinates against those on the Hill Bagging website and from LIDAR analysis.  Once data were processed it was obvious that the Trimble data set was not good, which was not a surprise considering the enclosed nature of where it was taken from, therefore this will not be used.  The co-ordinates confirmed we were approximately 100 metres from the high point of the hill.  Hopefully a repeat ascent in winter to the true summit will give my legs a chance to survive the experience, when wearing trousers instead of shorts will protect them from being scratched and bloodied as they had been today. 

 

Survey Result: 

 

Cefn Coch (significant name change)

Summit Height:  86.6m (LIDAR) (significant height revision)

Summit Grid Reference:  SH 61030 39620 (LIDAR)

Bwlch Height:  51.5m (LIDAR)

Bwlch Grid Reference:  SH 61461 39763 (LIDAR)

Drop:  35.1m (LIDAR) (30-99m Sub-Twmpau reclassified to 30-99m Twmpau)

Dominance:  40.51% (LIDAR)

 

 

For further details please consult the Trimble Survey Spreadsheet

 

 

 

 

Mapping Mountains – Trimble Surveys – Moelwyn Mawr

 

22.09.21  Bryn y Gwynt (SH 599 449) 

LIDAR image of Bryn y Gwynt (SH 599 449)

This hill entered the ranks of P30s in 2018 due to LIDAR analysis conducted by Aled Williams and today it was time for him to visit his new hill!  However, this was not our original plan as we had hoped to visit Moel y Dyniewyd (SH 612 477) and its accompanying hills, but the weather for such a walk was not encouraging with low gloom and drizzled rain, and although the forecast gave for a brighter afternoon, we didn’t fancy the thought of heading up this hill in unfavourable conditions, getting wet in the process, with the prospect of wandering around in wild surrounds trying to pinpoint summit and bwlch positions.  Therefore, we needed a plan B and Aled quickly came up with one; visit a number of lower heighted P30s that neither of us had been to, including the relatively recent new P30 of Bryn y Gwynt. 

This hill was originally listed as Coed Hafod y Llyn in the Welsh P30 lists published on Geoff Crowder’s v-g.me website.  Its name was changed to Bryn y Gwynt due to local knowledge from Aled, with this name also appearing on the series of Ordnance Survey Six-Inch maps.  As well as reclassifying this hill to P30 status, the original LIDAR analysis also promoted Bryn y Gwynt to Dominant status. 

Extract from the Ordnance Survey series of Six-Inch maps

Our quickly re-arranged plan was perfect as a wooded hill would give us shelter from the drizzled rain that still fell as we got our boots on, having parked just off the A4085 road on a track that runs parallel with the train line. 

As we set off the hill loomed above us, with its whole upper section covered in deciduous trees, which on many an occasion can be a delight to walk through.  However, on other occasions deciduous woods can be hellish with no semblance of a path, with going tough through all manner of undergrowth with brambles being the main obstacle.  This hill had a bit of both, but in the main it was a lovely place to walk in. 

Aled leading the way up Bryn y Gwynt

Aled navigated us upward over rich greened rising slopes through mature woodland with plenty of space between trees and occasional rocks interspersed amongst the greenery.  It was a wonderful place to be on such a morning, but with the added bonus of autumnal colour that in a few weeks will adorn this hill, it must be a sheer delight to then visit. 

Without the aid of ten figure grid references for this and the next two summits we visited, each walk was dependent upon finding our own way to the high point, which for me today required contentedly following Aled, who made good steady progress up the hill.  However, this was still an unusual experience for me, as for each walk and survey I usually come prepared with a mass of noted detail, including summit feature and all necessary ten figure grid references for both summit and adjoining bwlch. 

We reached a point that looked to be the summit; I took a few photographs and started to assess the rock that Aled was now standing on for Trimble placement.  Before setting the equipment up we decided to continue in to the wood as ground farther on looked as if it was higher, and so it proved and significantly so. 

The second point we reached was definitely the summit and soon the Trimble was set up atop my rucksack, with the measurement offset noted between its internal antenna and the ground at its base and it was soon quietly beeping away collecting individual datum points. 

Gathering data at the summit of Bryn y Gwynt

Once allotted data were gathered and stored, I closed the equipment down, took a few photographs and packed it away.  We now reversed our inward route avoiding all steep drops and soon found ourselves back on the track with Aled’s car about 100 metres away.  One wooded hill visited and two more to go. 

 

Survey Result: 

 

Bryn y Gwynt (significant name change)

Summit Height:  59.9m (converted to OSGM15, Trimble GeoXH 6000) (significant height revision)

Summit Grid Reference:  SH 59949 44919 (summit relocation confirmed)

Bwlch Height:  28.0m (LIDAR)

Bwlch Grid Reference:  SH 60224 45248 & SH 60226 45258 & SH 60227 45259 (LIDAR)

Drop:  31.9m (30-99m Twmpau addition) (30-99m Sub-Twmpau reclassified to 30-99m Twmpau)

Dominance:  53.21% (Dominant addition)

 

 

For further details please consult the Trimble Survey Spreadsheet

 

 

 

 

Mapping Mountains – Trimble Surveys – Elenydd

 

15.10.20  Castell (SN 585 789) 

The summit area of Castell with Pendinas in the background

One of the beauties of hill bagging is the element of exploration as a list of hills will take you on an adventure to places otherwise not visited.  Many of these sink to the recesses of memory where one hill merges in to another, whilst some linger in memories eye.  I am sure Castell will be a part of the latter, as today it shone in early morning autumnal light, looking out toward the coast that sprinkled azure like to the distant horizon. 

Today consisted of hill bagging in the ever welcome company of Charles Everett.  We met in Llangurig and I then drove west with Charles navigating on a myriad of narrow country lanes to our pre-planned parking spots for mini-expeditions to nine hills that took a very leisurely, all day to visit. 

Our first hill was Castell, which prior to our visit I had analysed via LIDAR, as I had for all our subsequent hills, with only one summit of the nine not as of yet having LIDAR coverage.  LIDAR is proving a great help when out surveying, and its accuracy in position is an extremely welcome aid and addition.  

LIDAR image of Castell (SN 585 789)

Driving west toward Aberystwyth, Charles then navigated us over the Afon Ystwyth to a narrow lane leading east and then north of the hill.  Google Earth had helped pinpoint suitable parking places and we were soon walking back up the lane to where open hillside rose steeply above.  Approaching the hill from this direction avoided the wood that fringes the lower part of this hill. 

Dew laden and shaded grass swept upward toward the summit of Castell with ever widening views behind us toward the north, where the sea glistened and the monument to the Duke of Wellington on the summit of Pendinas (SN 584 802) was ever present.  I’d surveyed Pendinas in October 2018 and it proved a fine viewpoint. 

Pendinas from the ascent of Castell

The upper part of Castell as its name implies is crowned by an ancient hillfort.  This is steep sided and as Charles headed up I lingered to admire the view.  As I crested the grassed rampart Charles was busy clearing a section of the summit of gorse, which I appreciated. 

Gathering data at the summit of Castell

When I joined Charles near the summit a small herd of cows sauntered through a gap in the earthen ramparts to join us on the inner part of the ancient hill fort.  They seemed interested in what we were doing, but as the Trimble gathered its allotted data, they thankfully kept a safe distance from the equipment, no doubt partly discouraged by the copious amount of gorse. 

Heading on to the ramparts to see what the Trimble is doing

To our south morning mist lingered in the valley, highlighted by the low sun, it was so wonderful to be here quietly surveying the hill in Charles’ company as the cows grazed their way across the summit area. 

Mist laden valley

Once the Trimble was packed away we headed toward a gate and then veered right down the steep field and back to the narrow lane.  Arriving at the car the walk and survey had taken just over 45 minutes and was a fine start to the day’s proceedings.  The next hill on our route is listed as Bryn Bras (SN 573 772) and was no more than 2km to our south-west. 

 

Survey Result: 

 

Castell (significant name change)  

Summit Height:  77.2m (converted to OSGM15, Trimble GeoXH 6000) (significant height revision)

Summit Grid Reference:  SN 58516 78997 (Trimble GeoXH 6000)

Bwlch Height:  42.3m (LIDAR)

Bwlch Grid Reference:  SN 58197 78954 (LIDAR)

Drop:  34.9m (Trimble GeoXH 6000 summit and LIDAR bwlch) (30-99m Sub-Twmpau reclassified to 30-99m Twmpau)

Dominance:  45.21% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

For further details please consult the Trimble Survey Spreadsheet

 

 

 

 

Mapping Mountains – Trimble Surveys – Mynydd Twr

28.10.18  Mynydd Bach (SH 389 767)  

Visiting the summit of this hill seemed an easy affair, as logged ascents on the Hill Bagging website mainly used the access track to the north-west that leads to the two high masts and covered reservoir positioned on the summit area of the hill.  As well as giving an easy and convenient ascent it was also a short one, as it only involved a couple of hundred metres to the top.

However, as I drove up the narrow lane and arrived at the start of the track I found a high metal fence barring access, where the fence ended each side was well protected with brambles and unforgiving amounts of unsavoury undergrowth.  I parked my car for a good inspection and did consider trying to climb the locked fence, but smiled at the thought as I knew I would not be able to do this, even if wanting so, which by the way, I didn’t.

Having walked a short distance on the lane either side of the metalled fence I realised I would not be gaining access to the hill from this direction and therefore drove the short distance back down the lane to the small community of Gwalchmai and then drove north up another narrow lane which brought me to the east of the hill.  I found parking beside a gate that gave access to another track leading toward the hill, I decided to investigate.

The track led through a paddock where three horses were standing in the morning sun, one showed particular interest in me as I quietly headed up toward a mass of gorse, bracken and brambles with the summit just beyond.  This form of undergrowth is prevalent on many of the lower hills on Ynys Môn, and all that I have encountered can either be bi-passed or bashed through, but summer ascents wearing shorts is definitely not recommended!

The high ground of the paddock led me to two gates which gave access to an old stone wall and the mass of unsavoury undergrowth on the other side, but as the masts and the summit of the hill were now within reach there was only one thing for it, and within a minute or so I was over the remnants of the wall and heading through the gorse, bracken and brambles.  This conveniently led directly to the natural high point of the hill which LIDAR analysis gives as ground close to a small fenced compound where one of the masts is situated.

Within a few minutes I’d assessed the ground, stomped on a few brambles and set the Trimble up to gather data.  As the set-up position was beside the compound amongst lush vegetation I decided to gather a ten minute data set.

The Trimble set-up position at the summit of Mynydd Bach

As the Trimble quietly beeped away gathering its allotted data I roamed around the summit area, climbing the outer steps to the fenced reservoir and looking back on the Trimble which was hard to see through the mass of gorse and brambles.

Once data were gathered and stored I closed the equipment down, packed it away and tried to remember my inward route back through the unsavoury stuff.  Eventually I clambered over the old wall back on to greened land where the friendly horse wandered my way and followed me as I headed back through the paddock to my car.  All that remained was to make place-name enquiries as the hill remains unnamed on the map.

Gathering data at the summit of Mynydd Bach

The first house I called at was next to where my car was parked; the occupant was obviously in bed when I knocked on the door as when he opened it he was bare chested and still doing his trousers up, we talked for a number of minutes and he kindly directed me down the lane to the first of two small houses where he said the elderly woman would probably be able to help.

I walked down the lane toward the house with the rough and rocky slopes of the hill on my left, as I did so a man appeared and walked toward a plot of land where his daughter was planning to live.  Gwyn Thomas lived at one of the houses I’d passed on the lane; the hill was on the other side of the road to where his daughter was planning to live and was at the back of Gwyn’s house.  I introduced myself and explained my interest in hill names and asked if he knew a name for the hill; he replied immediately and told me its name is Mynydd Bach.

Gwyn Thomas with Mynydd Bach in the background

We talked for a number of minutes before I headed back up the lane after thanking Gwyn for his time.  Mynydd Bach is a proper little mountain, rough and rocky and with extensive views from its summit.  I was glad to have visited, even though the undergrowth had proven problematic, another hill bagged and just as important; another name documented.    

Survey Result:

Mynydd Bach (significant name change) 

Summit Height:  96.5m (converted to OSGM15, Trimble GeoXH 6000) (significant height revision)

Summit Grid Reference:  SH 38964 76773 (Trimble GeoXH 6000)

Bwlch Height: c 64m (interpolation)

Bwlch Grid Reference:  SH 40259 77918 (interpolation)

Drop:  c 32m (Trimble GeoXH 6000 summit and interpolated bwlch)

Dominance:  33.66% (Trimble GeoXH 6000 summit and interpolated bwlch)

For further details please consult the Trimble Survey Spreadsheet