Mapping Mountains – Trimble Surveys – Craig Berwyn

 

26.11.20  Moel yr Henfaes (SJ 077 385), Y Drum (SJ 082 378), Pt. 581.7m (SJ 086 373) and Cefn Dylif (SJ 089 369) 

Y Drum (SJ 082 378)

For many years it was as if I was walking with blinkers on, as I concentrated on the higher 2,000ft mountains and rarely ventured to any hill that was lower.  It was the listing of the Deweys that opened my eyes to the lower hills, closely followed by the remaining Twmpau.  And two hills on today’s walk show how blinkered my vision was, as the first hill; Moel yr Henfaes I had only visited once before in August 2000, whilst the last hill; Cefn Dylif I had visited on 21 occasions.  Both hills are on the same ridge, with the former at its north-westerly end and the latter joining the main Berwyn ridge.  But the difference in totals is purely down to height. 

I was joining Mark and Aled for this walk and the arrangements to meet and route and hills to visit were quickly organised the preceding evening.  We met in Cynwyd and took two cars to the end of a steep minor road and parked beside the farm buildings at Rhos-y-maerdy.  This was at 350m, which helped somewhat. 

The way to the hill

I set off a few minutes before the others and made my way up the track that continues from the end of the paved road.  Conditions were beautiful with the remnants of mist still in the valley below and the higher Berwyn tops clear with autumnal blue sky above, whilst further to the north and west many of the higher tops were cloaked in a blanket of grey. 

The view west with mist in the valley and a grey murk over the higher tops

Breaking away from the track a field led up beside the Nant y Cwm toward the bwlch between Moel yr Henfaes and Y Drum, in time this would be surveyed, but our first objective was the summit of Moel yr Henfaes.  I heard Mark and Aled before I could see them, with their voices echoing against the stillness of the morning.  By the time they emerged on to the field below I was now immersed in heather, making slow, rough progress ever upward. 

An occasional sheep path amongst the heather helped, but in the main it was rough and pathless.  Bit by bit height was gained and I eventually reached the ridge and swung left up toward the summit.  Within a minute or so of arriving on top I was joined by Mark and Aled. 

As the Trimble gathered summit data we sat and stood close to the cairn in the morning sunshine looking out across a myriad of hills, some clear, others still cloaked in grey, but all inviting. 

Gathering data at the summit of Moel yr Henfaes

It was only a short distance back toward the connecting bwlch which is the critical one for the next hill on the ridge; Y Drum.  This was in a sea of tussock grass and heather and as I stood knee deep in the stuff Mark used his hand-held GPS to zero in to where the 551m spot height appears on the ground.  The whole area was awash with large tussocks and this was our best way to approximate where the bwlch lay.  Before setting the Trimble up, I assessed the lay of land and as I positioned the equipment on top of my rucksack, Mark and Aled headed toward the summit of Y Drum. 

Gathering data at the bwlch of Y Drum

Once data were gathered and stored I closed the equipment down, packed it away and stumbled my way to a part of the hill where the heather had been cut, this at least enabled easier underfoot conditions, and the temptation of a grazed and closely cropped grassy field was not too far away.  This I reached and within a couple of minutes I joined the others at the summit. 

Moel yr Henfaes (SJ 077 385)

The summit of Y Drum is attractive and consists of a small rocky knoll.  After setting the Trimble up to gather data we each sat, socially distanced on a rocky rib that extended out from the summit area.  A few minutes later it was time to head off again, this time down to the bwlch that is the critical one for Moel yr Henfaes. 

Gathering data at the summit of Y Drum

I headed off before the others and had the Trimble set up gathering data as they waved and headed past me up toward the summit of a 582m map heighted hill that had recently been promoted to Sub-Uchaf status.  The proceeding summit and bwlch survey will confirm its status one way or the other. 

Gathering data at the bwlch of Moel yr Henfaes

Its summit was beside the ridge fence overlooking a steep drop down to its bwlch.  By the time I arrived at its high point, Mark and Aled had assessed the lay of the land and chosen the place for Trimble placement.  As the equipment gathered summit data, Aled headed down to assess the bwlch.  Once data were gathered and stored I joined him, whilst Mark headed off and waited for us just beyond the bwlch. 

Mark and Aled heading to the summit of what used to be a 500m Sub-Uchaf

We took two data sets from the area of the bwlch, each on the hill to hill traverse.  The ground above and to our north was steep, and whilst the Trimble gathered its sixth and seventh data set of the day we debated whether this hill would retain its sub status. 

Only one hill remained to survey and after closing the equipment down I followed Mark and Aled up a vehicle track on the moor toward a fence and then across it to the rocky rib and cairn that make up the summit of Cefn Dylif.  The last time I had visited this summit was in August 2007, a lot has changed in my life since then, some good, some not so good, and although it is clichéd to say; the allure of the hills remain as a constant. 

Gathering data at the summit of Cefn Dylif

After the summit was surveyed we headed down to the bwlch which has the continuation of our inward track crossing it, before it continues down following the course of the Nant Rhydwilym to the Afon Ceiriog.  It was easy to pinpoint the critical point and as the Trimble was set up Mark and Aled went to find the book beside the memorial to the Wayfarer. 

Gathering data at the bwlch of Cefn Dylif

Many years ago a form of garage stood at this bwlch, its roof finally gave up and collapsed and now any lingering remnants have been removed.  It leaves this part of the Berwyn garage free, and all the better for it. 

The Wayfarers Memorial

The bwlch survey was the ninth data set of the day and once safely stored I closed the Trimble down, took a few photos and packed it away and we headed down the track back to the awaiting cars.  It had been another good day on the hill. 

Postscript: Since the survey of these hills with the Trimble GeoXH 6000 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.  Y Drum and Cefn Dylif have also been surveyed by Alan Dawson using a Leica RX1250.  Therefore, it is a combination of these surveying methods that form the listed data.

 

Survey Result: 

 

Moel yr Henfaes  

Summit Height:  584.5m (converted to OSGM15)

Summit Grid Reference:  SJ 07755 38589

Bwlch Height:  547.4m (converted to OSGM15)

Bwlch Grid Reference:  SJ 08418 37600

Drop:  37.1m

Dominance:  6.34%

 

 

Y Drum  

Summit Height:  579.1m (converted to OSGM15, Trimble GeoXH 6000 and Leica RX1250)

Summit Grid Reference:  SJ 08247 37893 (Trimble GeoXH 6000 and Leica RX1250)

Bwlch Height:  549.1m (converted to OSGM15, Leica RX1250)

Bwlch Grid Reference:  SJ 07986 38259 (Leica RX1250)

Drop:  30.0m (Trimble GeoXH 6000 and Leica RX1250 summit and Leica RX1250 bwlch) (500m Sub-Twmpau reclassified to 500m Twmpau) (Dewey addition)

Dominance:  5.18% (Trimble GeoXH 6000 and Leica RX1250 summit and Leica RX1250 bwlch)

 

 

Pt. 581.7m  

Summit Height:  581.7m (converted to OSGM15)

Summit Grid Reference:  SJ 08664 37360

Bwlch Height:  568.7m (converted to OSGM15)

Bwlch Grid Reference:  SJ 08659 37320

Drop:  13.0m (500m Sub-Uchaf deletion)

Dominance:  2.23%

 

 

Cefn Dylif  

Summit Height:  618.5m (converted to OSGM15, Leica RX1250) (significant height revision)

Summit Grid Reference:  SJ 08943 36943 (Leica RX1250)

Bwlch Height:  581.3m (converted to OSGM15, Trimble GeoXH 6000)

Bwlch Grid Reference:  SJ 09068 36590 (Trimble GeoXH 6000)

Drop:  37.3m (Leica RX1250 summit and Trimble GeoXH 6000 bwlch)

Dominance:  6.03% (Leica RX1250 summit and Trimble GeoXH 6000 bwlch)

 

 

For further details please consult the Trimble Survey Spreadsheet

 

Mapping Mountains – Trimble Surveys – Craig Berwyn

02.09.17  Garnedd Wen (SJ 131 311) and Mynydd Mawr (SJ 133 286)

Mynydd Mawr (SJ 133 286)

Having been away from the hills for two months I wanted a fairly easy walk to ease my way back on to them and combining Garnedd Wen with Mynydd Mawr was a perfect way for my right knee to recuperate without being tested too much.

A narrow road heads eastward from Maen Gwynedd toward Llanarmon Dyffryn Ceiriog and the grass verge close to the connecting bwlch between the two hills proved an ideal parking spot.

I set off at 8.30am just as the early chilled morning gave way to the first warmth of the day.  It felt good to be back on the hills amongst quiet surrounds with a radiant blue sky above and just a breath of breeze adding to the beauty of patch worked green fields which were dotted in white sheep smothering the land.

A vehicle track on the hillside soon gave way to a closely cropped grassy field which led up toward the summit of my first of two hills of the day; Garnedd Wen, which is listed as a 400m Sub-Pedwar.  Skirting the summit I headed down toward the hill’s critical bwlch and aimed for a gate giving access on to moorland and a track heading toward a fence that crosses the bwlch in a hill to hill direction.  After assessing the lay of land from a number of directions I decided that one of the fence posts was as good as any to be declared the position of this hill’s critical bwlch and set the Trimble up accordingly.

As the Trimble gathered its customary five minutes of data I stood back and admired the main Berwyn ridge which from this viewpoint butted against the lay of land as it blocks the course of west to east ridges, immediately in front was the continuation of steep land toward the ridge leading to Mynydd Tarw, however tempting this was I realised that a gentle walk was required to accustom my knee to the rigours of hill walking and over ambitious plans may prove detrimental in the long term.

The main Berwyn ridge

Gathering data at the critical bwlch of Garnedd Wen

Y Garn (SJ 080 272)

With the Trimble packed away I headed to the summit of Garnedd Wen where the remains of quartz rocks were jumbled together overlooking the greened and pleasing slopes of Mynydd Mawr, a marvellous scene to look at for someone who has been devoid of mountain views for the last two months.

Mynydd Mawr from the quarzt rocks atop Garnedd Wen

I again positioned the Trimble on a fence post having judged the land at its base to be the summit of the hill, this time improvising and laying my Goretex coat on the post as a part of the barb wired fence had been hammered in to its top, by placing the Trimble on top of my coat it protected its underside and elevated it above its immediate surrounds, once the offset was measured with a steel tape it bleeped away gathering its 300 allocated datum points.

The gentle north-western slopes of Mynydd Mawr

Gathering data at the summit of Garnedd Wen

By now the first clouds had bubbled up in an otherwise spotless blue sky, and by the time I retraced my steps back down the hill to the narrow road more clouds had appeared.  After taking a data set at one of two possible bwlch positions of Mynydd Mawr I slowly plodded up beside a fence toward its summit, the north-easterly ridge of this hill is relatively broad and long, and gave chance for my mind to wander as height was slowly gained.

The summit of Mynydd Mawr is crowned by a triangulation pillar with elevated land approximately 5 metres to its west and 19 metres to its east, with the high point of each on exposed rock that forms a small rock crest which is more prominent on the eastern side.  I took data sets from each high point before setting off back on my inward route.

Gathering data from the point 5 metres west of the trig pillar on Mynydd Mawr

Gathering data from the point 19 metres east of the trig pillar on Mynydd Mawr

The Trimble set-up position at the summit of Mynyd Mawr with the trig pillar in the background

Following the fence line back down the hill the profile of Y Gurn looked forever majestic, a wonderful hill considering its relatively lowly height.  All that remained was to take a second data set from the continuation of the land that makes up the bwlch of Mynydd Mawr, this time from the position that I considered to be the critical point, as this was beside a gate that led to the narrow road where my car was parked it was a convenient place to end the day’s surveying.

Y Gurn (SJ 184 293)

Gathering data at the critical bwlch of Mynydd Mawr

The walk proved ideal in length to test my recently operated on right knee, and was also ideal to re-accustom myself to the hills and using the Trimble after a two month layoff.  

Survey Result:

Garnedd Wen 

Summit Height:  496.0m (converted to OSGM15) 

 

Summit Grid Reference:  SJ 13181 31156

Bwlch Height:  472.3m (converted to OSGM15)

Bwlch Grid Reference:  SJ 13046 31401

Drop:  23.8m 

Dominance:  4.79%

Mynydd Mawr

Summit Height:  534.7m (converted to OSGM15)  

Summit Grid Reference:  SJ 13306 28624

Bwlch Height:  430.0m (converted to OSGM15)

Bwlch Grid Reference:  SJ 14135 30581

Drop:  104.6m 

Dominance:  19.57%

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Trimble Surveys – Craig Berwyn

19.06.17  Gurn Moelfre (SJ 184 293) only bwlch surveyed, Hen Graig (SJ 176 309), Blaen Trinant (SJ 172 319), Cefn Hir Fynydd (SJ 154 311) and Pt. 432.2m (SJ 163 301)

Blaen Trinant (SJ 172 319)

With the temperature forecast to edge toward 30° I set off early and navigated the narrow country lanes north-east of Llanrhaeadr-ym-Mochnant toward Pantglas Ucha; a farm whose tracks into the hills gave options for parking.  This, and the area around Llanfyllin has drawn me back on numerous occasions of late, the hills hereabouts are mainly green pasture, but are generally steep in nature and shapely in profile, with the whole area quietly nestled in beautiful landscape.

My first objective was to survey the critical bwlch of Gurn Moelfre; one of the most distinct hills in the neighbourhood.  LIDAR data gives this hill’s bwlch on the narrow lane to the north-west of its summit.  Leaving my car I walked down the lane toward the bwlch as Comins and Moel y Gwelltyn; two hills I’d visited less than two weeks ago, looked down from across the valley, both hills have a striking profile and they looked welcoming in their greened summerness with a foreground of sheep whose morning slumbers had been disturbed as I’d passed.

Gurn Moelfre (SJ 184 293)

The shapely profile of Comins on the left and Moel y Gwelltyn on the right

All was quiet at the bwlch as I set the Trimble up, a long wait then developed, one of the longest I’ve had to endure as it took 40 minutes for the required 0.1m accuracy level to be attained before data should be logged.  I found this slightly wearisome as I wanted to gain height before the heat of the day hit.  I checked the equipment every five minutes hoping that the magic 0.1m would be finally showing, during this long wait two cars passed, each I flagged down and waved around my rucksack, the drivers must have wondered what on earth I was doing as it was barely past 8.00am.  I spent much of the time in thought, letting my mind wander to weird and wonderful places, occasionally I would look and concentrate on the mature trees either side of where the Trimble was positioned, they were marvellous things, huge and dominant with luxuriant green leaves edged in the morning’s sun, a dragon fly flew past and I watched it zigging and zagging to and fro, up and down the lane and into the hedgerow and near trees.  The Trimble reached 0.11m accuracy and I thought it would only be another two minutes before the 0.1m mark was attained, unfortunately the accuracy level bounced back up and I almost gave up the whole process, but thankfully I persevered as a few minutes later the magical 0.1m showed itself and I quickly pressed ‘Log’ and hoped that no other cars would appear in the next five minutes, thankfully none did and once five minutes of data were stored I proceeded on a track leading toward Hen Graig; my first hill of the day.

Gathering data at the critical bwlch of Gurn Moelfre

Dappled light

Even at this relatively early hour the sun beat down, I’m prone to flake out when it’s too hot and I’m on the hill, and have experienced times when I’ve wobbled and felt ill due to excess heat, so had come well prepared with four litres of water.  However, as I slowly made progress up the track bending itself around the western slopes of Hen Graig the heat smothered me, and with hardly a breath of breeze it felt like continental Europe was visiting the Welsh uplands for the day.

Pt. 432.2m (SJ 163 301) from the ascent of Hen Graig

Leaving the main track until later I followed a fence line and green track over the connecting bwlch which I planned on surveying on my way down and slowly plodded to the small rocky knoll at the summit of Hen Graig, I’d visited this summit once before in July 2003 and had then connected it up with the other hills I planned on visiting today, but had approached them from a different direction.

Gathering data at the summit of Hen Graig

Leaving the summit I retraced my route back through copious amounts of thistles to the connecting bwlch and used LIDAR data to zero in to the critical point.  As the Trimble gathered its allotted five minutes of data I sat on the earthen bank attached to a fence and rested.

Gathering data at the critical bwlch of Hen Graig

The track I had used on my ascent continued from the area of the bwlch toward the summit of Blaen Trinant, a hill I had previously surveyed using my old wooden staff.  Away in the distance a screeching sound of a tractor floated across the land, I eventually spotted it busying itself on a steep slope.  All around the lushness of summer enveloped the land with green growth seemingly having no bounds, sheep tried in vain to keep in shade prostrate on rutted tracks until disturbed by my approach.  Bulbous cloud sprang up, a greyed white with a hazed blueness to the sky washing out much of the colour, the land slept, still and sombre, quiet in a heat haze.

Leaving the track I headed toward the summit of Blaen Trinant which consists of grazed grass beside the debris of a few breeze blocks.  A constant companion during the early hours was the profile of Gurn Moelfre, it peered down upon proceedings with an almost disdainful look, with its height and shapely outline giving it dominance upon its immediate land.

Gathering data at the summit of Blaen Trinant

Although I’d paced myself and due to the surveying, rested frequently, the heat was piercing and sweat glistened from every pore as I walked down to another rutted track where the critical bwlch of Blaen Trichant is positioned.  I soon had the Trimble set up and gathering data.

Gathering data at the critical bwlch of Blaen Trinant

By now I was starting to wilt and although I had thought of also visiting Garnedd Wen I decided to evaluate the time and how I felt after reaching the high road where the bwlch of my next hill; Cefn Hir Fynydd is placed.  The track I was on forms a part of the Upper Ceiriog Way, and this section led across the upper northern side of Cefn Hir Fynydd, this hill is elongated and its summit was ahead of me shimmering into view, by now I rested at each fence junction where a gate gave further access on the track.  I left the track to step over a dilapidated and rusting gate to gain access to the long grassed summit ridge, this I followed using the grid reference produced by Aled through his analysis of LIDAR data to take me to the high point, this proved to be at the far end of the ridge, by the time I arrived at the high point I needed a rest.

The grass proved so long I flattened it at the summit to give the Trimble a better chance of satellite reception, and once activated I stood back and waited until the customary five minutes of data were gathered.  Just below me a gate gave access back onto the track which led down to the high road where the critical bwlch of Cefn Hir Fynydd is placed, again the grid reference produced by Aled’s analysis of LIDAR data took me to the point where data should be logged, thankfully the convenience of a fence post meant that I could set the Trimble up at this grid reference giving it elevation above its immediate surrounds and also safeguarding it from cars that may come this way.  As data were collected I considered my onward route, I had planned on visiting Garnedd Wen, a hill I had not visited before, and surveying its bwlch and summit, and the critical bwlch of Mynydd Mawr which is placed further up the narrow road from where I now was.  However, I knew the heat was taking its toll and I was beginning to flag, I looked up toward the land leading to Garnedd Wen and deciding that this hill could wait for another day I packed the Trimble away and followed the narrow road down south-eastward toward Pant-y-maen farm, by the time I arrived it felt as if the whole land was baked in heat as a stillness pervaded all.

Gathering data at the summit of Cefn Hir Fynydd

Gathering data at the critical bwlch of Cefn Hir Fynydd

Garnedd Wen, too hot and too far for me today

I knocked at the door hoping to make place-name enquiries as the last hill of my walk stood steeply above the farm and is unnamed on Ordnance Survey maps, no one was in.  I called out as I walked through the farm yard wondering if someone was working in an outbuilding, again, no response.  Before heading toward the green track leading from the farm yard to the bwlch of this hill I stopped at a water trough where the gentle sound of cascading water flickered in the sunlight, I spent time cupping handfuls of cooling water and splashing it over my face, within a few minutes of leaving the farm and wandering up the green track, my face was dry.

A well needed refreshing break

The bwlch of the last hill proved a blaze of green and having assessed the lay of land I took two data sets, both near one another before packing the Trimble away and slowly gaining height to another track that led up the steepening slopes of this last hill.  I stopped frequently to regain breath and wipe sweat from my brow.

Gathering data at the critical bwlch of Pt. 432.2m

The high point was in a grazing field and as the Trimble gathered data I stood back and savoured the view and the imminent prospect of getting back to my car to change into dry clothes and get my walking boots off. 

Gathering data at the summit of Pt. 432.2m

Heading down the field I spotted a vehicle track through the grass that led to a gate which gave access on to the track where my car was parked, it was only a short route down and one that I took slowly, arriving at the car was a pleasure and getting my boots off more so. 

Survey Result:

Gurn Moelfre

Summit Height:  523m (spot height)

Summit Grid Reference:  SJ 18445 29388 (hand-held GPS via DoBIH)

Bwlch Height:  289.5m (converted to OSGM15)

Bwlch Grid Reference:  SJ 17806 29915

Drop:  234m

Dominance:  44.65%

Hen Graig

Summit Height:  433.0m (converted to OSGM15) 

 

Summit Grid Reference:  SJ 17668 30905

Bwlch Height:  392.9m (converted to OSGM15)

Bwlch Grid Reference:  SJ 17457 31308

Drop:  40.1m

Dominance:  9.27%

Blaen Trinant

Summit Height:  442.2m (converted to OSGM15)  

Summit Grid Reference:  SJ 17253 31962

Bwlch Height:  416.8m (converted to OSGM15)

Bwlch Grid Reference:  SJ 16857 31848

Drop:  25.5m (400m Sub-Pedwar status confirmed)

Dominance:  5.76%

Cefn Hir Fynydd

Summit Height:  464.6m (converted to OSGM15) 

 

Summit Grid Reference:  SJ 15499 31174

Bwlch Height:  411.7m (converted to OSGM15)

Bwlch Grid Reference:  SJ 14575 30922

Drop:  52.9m

Dominance:  11.38%

Pt. 432.2m

Summit Height:  432.2m (converted to OSGM15) 

 

Summit Grid Reference:  SJ 16375 30157

Bwlch Height:  357.9m (converted to OSGM15)

Bwlch Grid Reference:  SJ 16231 30803

Drop:  74.4m

Dominance:  17.20%

For further details please consult the Trimble Survey Spreadsheet