Mapping Mountains – Trimble Surveys – Mynydd Epynt

 

02.11.24  Pt. 428.9m (SO 035 449) 

Pt. 428.9m (SO 035 449)

Lack of daylight hours dictated that this was our last hill of the day.  It was 3.20pm when we set off from the narrow road that bisects this hill from its higher neighbour to the north.

At this time of year the hill consists of grass and dulled autumnal bracket.  Green tracks lead across the hill, bisecting at points, giving both farmers and hill walkers ease of passage.  The underfoot conditions and the rolling nature of the land hereabouts give a semblance of gentleness to the hill.  It was an ideal choice for our last hill of the day and would give Charles a new P30.  I had previously visited the hill in 2008 when including it in a good lengthy circuit with its higher northerly neighbour. 

Convenient place to park a car

Leaving the car I followed Charles on a green track that contoured its way around an intermediary bump.  Although there was no breeze, a slight chilled feeling pervaded the hill as late afternoon gently turned to dusk.  This only added to the quality of being out in such land. 

Heading for the hill

Wet surrounds indicated the low points of the track as it continued around a second intermediary bump, which again we bi-passed with the track contouring its way around.  From here it was only a short distance to the high point of the hill which reared up in front of us as an elongated flattish broad ridge.

Prior to visiting I had LIDAR’ed the hill and although the ten figure summit grid reference proved not to be needed, as I eventually resorted to sighting by eye, I nevertheless initially used the Trimble as a hand-held device to zero in on what LIDAR gives as the summit position. 

LIDAR image of Pt. 428.9m (SO 035 449)

However, the summit consists of numerous small bumps, a number of which vied for the high point.  It was now that I dispensed with the grid reference produced by LIDAR and sighted across the top from a number of directions before choosing what was judged as the high point.  The Trimble was soon set up gathering data. 

Charles heading for the summit

During data collection I stood away from the equipment writing all necessary detail in my surveying notebook.  Once five minutes of data were gathered and stored I walked back to the equipment, turned it off and took a few photos.  Before packing it away we were joined by an enthusiastic Tess the dog and her human companion, who unfortunately neither of us asked her name.  I had spotted her a while earlier as she ran across the hill, she was now heading toward us and asked what we were doing, having thought we may be studying ferns. 

Gathering data at the summit of Pt. 428.9m (SO 035 449)

It was lovely meeting her; she lived on a small holding near by and used this and its adjacent hill to run on.  During the conversation Tess ran this way and that, a never ending four legged bundle of enthusiastic energy jumping up to greet us whilst barking her happiness. 

At the summit

As the two of them ran off down the hill we also headed down toward the near green track, and then retraced our inward route.  The walk had taken just over an hour and by the time we arrived back at the car, dusk was setting. 

 

Survey Result:           

 

Pt. 428.9m (significant name change)  

Summit Height:  428.9m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SO 03592 44968 (Trimble GeoXH 6000)

Bwlch Height:  396.7m (LIDAR)

Bwlch Grid Reference:  SO 03648 45409 & SO 03664 45405 (LIDAR)

Drop:  32.1m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  7.49% (Trimble GeoXH 6000 summit and LIDAR bwlch)  

 

 

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Trimble Surveys – Hirddywel

11.07.20  Allt y Moch (SO 022 849)  

Allt y Moch (SO 022 849)

In August 2003 I set out with good intention to reach the forested summit of Y Foel (SO 018 840).  After about 45 minutes I emerged out of the trees having had one of those adventures when you’re not sure where you’ve been or where you now are.  I salvaged the day by heading across the intervening valley and finding a forestry track that led me toward Allt y Moch.  I proceeded to survey this hill with my old basic levelling staff and concluded that it had approximately 29.4m of drop.  This method of surveying is only basic, but was responsible for a number of hill reclassifications.  Considering its method many results are accurate, however some aren’t, and this could be one of them as the latest online mapping suggests this hill to be a P30 and therefore I wanted to revisit and survey it with the Trimble GeoXH 6000.

Access to the hill is easy as there’s one or two places to park at the end of a narrow paved road that makes its way uphill toward one of the many access tracks that lead into the western part of the Pegwn Mawr range.  From here it was a short walk on the continuation of the track before taking a branch off on the left that led straight to this hill’s bwlch.

The track leading to the bwlch

I remembered from my last visit that the bwlch had some sort of construction on it, this proved to be a high sided large sheep fold.  Thankfully it wasn’t positioned over the critical point.  I spent an inordinate amount of time at this bwlch as it took seven attempts before the Trimble complied with my wishes and reached its 0.1m accuracy level before data should be logged.  At one point I removed its battery and then re-booted it.  Why this happened I do not know, but wonder if five months inactivity had made it sluggish, a little like its owner, perhaps.

During the first bwlch survey I decided to take at least one more data set on the valley to valley traverse, and during this second survey I decided a third was needed.  This would give a good spread of results and show the lay of land over a 20 metre or so distance.

Gathering data at the bwlch of Allt y Moch

A greened track led up from the bwlch toward the summit, it was so good to be in such a place, it wasn’t dramatic, but it was a hill and I’d missed their openness over the last four months during the enforced and necessary lock down.

Once at the summit I proceeded to take four further data sets, three from near to where the 421m spot height appears on the Ordnance Survey 1:25,000 Explorer map and one from where the summit ridge continues north-westward.  During each data set I stood below the Trimble and looked out to the west across miles of cultivated, forested and in patches wild land toward the higher hills of the Aran and Berwyn.

Gathering data at the summit of Allt y Moch

Packing the Trimble away I retraced my route back to the connecting bwlch and headed down beside a fence line which took me to within a few metres of where I’d parked my car.  Allt y Moch would be a fine addition to the Y Pedwarau, we’ll just have to wait for the data to be processed until its status is hopefully confirmed.

Survey Result:

Allt y Moch

  

Summit Height:  419.7m (converted to OSGM15)

Summit Grid Reference:  SO 02202 84938

Bwlch Height:  389.6m (converted to OSGM15, from subsequent Trimble GeoXH 6000 survey)

Bwlch Grid Reference:  SO 02366 84827 (from subsequent Trimble GeoXH 6000 survey)

Drop:  30.1m (400m Sub-Pedwar reclassified to Pedwar)

Dominance:  7.17%

For details on the second Trimble GeoXH 6000 survey of this hill

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Trimble Surveys – Esgeiriau Gwynion

19.11.19  Moel y Tryfel (SH 975 154)  

Moel y Tryfel (SH 975 154)

With reports on the Hill Bagging website that the upper section of Moel y Tryfel had been cleared of forestry it felt prudent to pay the hill a visit, and although until recent times this hill was listed as a marginal Pedwar, its summit and connecting bwlch had been LIDARed by Aled Williams, so its status was safe, but still, a Trimble summit survey wouldn’t go amiss.

LIDAR image of Moel y Tryfel

Today’s little wander was in the company of Mark Trengove, and with a late afternoon meal arranged at The Raven in Welshpool, once Mark had arrived at my home we could have a leisurely buttered crumpet or two with a mug of tea / coffee before heading west to the small community of Foel and the narrow minor road that leads in to the hills and more specifically to the base of Moel y Tryfel.

As I donned my wellies for the first time this season the sky above was hazy with high cloud delicately intermingled with a gentle and seasonal blue, however the forecast gave for cloud edging in from the west and as we walked through the farm yard close to where we had parked, the first glimmers of this dull greyed cloud mass was already on the horizon.

Heading for the hill

To our north the conifered area of Moel y Tryfel rose above pastured grazing fields, with mature trees hiding what we hoped was the de-felled summit area.  Our path contoured the hillside gaining height slowly and aiming for a gate which gave access through a brackened and gorse laden gap in the forestry, this soon led on to a wide forest track.  It was this track which in time would lead us around the easterly upper part of this hill and give us access to its summit area.

The gap through the trees leading to the forest track

We were told at the farm that the conifers were still being felled and to our north the distinct hum of machinery wafted across the hill.  We examined the LIDAR bwlch position before heading further up towards the summit, as it was immersed in conifers to the east of a minor forest track we headed back to the main track and continued skirting the upper easterly part of the hill.

Two or three rougher tracks head off up the hill from the main track, choosing the last of these we plodded our way up until close to the summit and then abandoned it in favour of a direct route to the high point.

Nearing the summit

The summit of Moel y Tryfel now consists of rough felled ground with newly planted trees adding greenery to the immediate surrounds.  We assessed the ground for the highest point and soon the Trimble was set up gathering its allotted data.

Gathering data at the summit of Moel y Tryfel

By now the western murk had quickly overtaken any semblance of blue that pierced the start of our walk.  The surrounding higher hills were now immersed in clag and it proved an ideal time to leave the summit and head back to the main forest track.  We hoped to continue round the northerly and westerly slopes of the hill on this track which in time would take us back to the farm we had parked at.  However, forestry operations stopped us as trees were being uprooted, their branches quickly skimmed off and their bulk cut, we did ask if we could pass but were politely told that we couldn’t, therefore we headed back up the track and reversed our inward route.

The afternoon ended with a good meal in The Raven before Mark headed home.  The day had proved excellent, with good company, a wee hill and walk followed by the meal.  It always amazes me how such a day can instantly refresh the soul.

Survey Result:

Moel y Tryfel 

Summit Height:  406.2m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 97503 15479 (Trimble GeoXH 6000)

Bwlch Height:  371.9m (LIDAR)

Bwlch Grid Reference:  SH 97947 15395 (LIDAR)

Drop:  34.3m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  8.44% (Trimble GeoXH 6000 summit and LIDAR bwlch)

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Trimble Surveys – Pumlumon

13.09.19  Newydd Fynyddog (SH 914 003), only bwlch surveyed

The land mass extending north from the higher summit of Bryn Amlwg comprises the 427m map heighted summit of Newydd Fynyddog.  Beyond this are slopes descending to the stream valleys below.

Newydd Fynyddog (SH 914 003)

The land taking in Newydd Fynyddog is quiet and consists in the main of grazing fields.  Its connecting bwlch is to the south-west of its summit and the critical point of this bwlch is close to the minor road that passes from Bontdolgadfan in the west to Talerddig in the east.  This bwlch is similar to its summit; quiet and peacefully situated.

I’d visited this hill once before in October 2013, but unsurprisingly had never visited its bwlch, until today.  The reason for visiting was to survey it, and this was the third of six planned roadside bwlch surveys that would take me on a road trip extending from Llanidloes to the road passing over Y Berwyn.  With many of these bylchau adjoined to high and prominent hills.

The bwlch of Newydd Fynyddog

I parked my car adjacent to a gate giving access in to the field where the bwlch of Newydd Fynyddog is placed.  I rarely park in front of a gate and this is not to be encouraged, but as I was only a minute or so walk from it I could easily move my car if a farmer wanted access.

The area of the bwlch proved a delightful place to spend 20 minutes and especially so as it was bathed in early afternoon sun that cast vivid clear colour.  I’d come prepared with a ten figure grid reference of where interpolation places this bwlch and once in the field spent a number of minutes assessing the lay of land, with the greened grass ebbing upward on the valley to valley traverse toward a fence corner, from which the land then ebbed downward.

One of two set-up positions where data were gathered for the bwlch of Newydd Fynyddog

I chose two positions to take data from, each on the hill to hill traverse, one of which was in a slight dip that encouraged me to think it the critical point, but which may prove otherwise.

Gathering data at the bwlch of Newydd Fynyddog

As data were gathered I stood and enjoyed the feel of being out, albeit not on a summit.  But this feeling was one to savour.  An occasional sound of someone working near land would wisp its way downward from a high field, otherwise the only other sound that broke the quiet surrounds was an occasional passing vehicle.

At the bwlch with Newydd Fynyddog in the background

Once data were gathered and stored I lazily made my way back to the gate and my car and proceeded to drive the short distance eastward to Talerddig where the fourth bwlch survey of the day awaited, that connecting to Pen y Fan.

Survey Result:

Newydd Fynyddog

Summit Height:  427m (spot height)

Summit Grid Reference:  SH 91452 00381 (hand-held GPS via DoBIH)

Bwlch Height:  289.4m (converted to OSGM15, Trimble GeoXH 6000)

Bwlch Grid Reference:  SN 90173 99835 (Trimble GeoXH 6000)

Drop:  138m (Trimble GeoXH 6000 summit and spot height summit)

Dominance:  32.24% (Trimble GeoXH 6000 summit and spot height summit)

  

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Trimble Surveys – Pumlumon

13.09.19  Pen y Waun Fawr (SN 878 949), only bwlch surveyed

The view down the Pennant gorge is unexpected and rather stunning as the ice aged glaciers have carved a great swathe of land and left an almost symmetrical steep sided gorge.  The view can be awe-inspiring.

The Pennant gorge

The land either side of this gorge is pastoral with greened grazing fields in time giving way to moorland.  When looking down the gorge the hill on the eastern side is known as Pen y Waun Fawr.  I’d visited its summit once before in October 2003 surveying hills with my old basic levelling staff as I did so.  Since these days LIDAR is now available and the summit of this hill has subsequently been analysed by Aled Williams.  However, LIDAR does not cover its connecting bwlch, and this was my next surveying objective during a day which comprised six roadside surveys, and all done in glorious sun drenched weather.

Pen y Waun Fawr (SN 878 949)

Ordnance Survey maps indicate that the critical bwlch for this hill is on or immediately beside the minor road that heads north toward Bontdolgadfan.  To check on the width of the road and parking I’d accessed a Google car via my laptop the previous evening and found the connecting bwlch for this hill was placed on the minor road.  Therefore, I would have to position my car directly over the bwlch and use the car’s roof as an improvised tripod.

Thankfully the minor road is just wide enough to squeeze one parked car adjacent to the mature boundary hedge and leave sufficient space for any vehicle to pass on the other side.  When I arrived I parked and spent a few minutes wandering down either side of the car assessing the lay of land.  Contouring on the OS Maps website implies that the critical point of this bwlch is beside a fence that heads downhill from the west, I judged the critical point to be a few metres further south, however the road hereabouts was relatively flat for ten metres or so.

Once I’d moved my car in to position, I placed the Trimble on its roof and measured the offset between its internal antenna and the ground below and proceeded to stand on my recently bought aluminium surveying steps, which proved ideal to see the Trimble’s screen and create the file whilst setting the equipment up to gather data.

The Trimble set-up position at the bwlch of Pen y Waun Fawr

During this the road remained relatively quiet with only an occasion passing cyclist and a rogue car or two.  Once the Trimble attained the 0.1m accuracy level before data should be logged I pressed ‘Log’ and moved the steps to the front of the car and walked a short distance away and politely gestured with a hand wave and smile at any vehicle that then passed.  Only one pulled up to ask if I was all right, with the presumption that my car may have broken down.  I thanked them for stopping but said everything was all right, except for the bwlch which really should have been in the adjacent field and not on the road!

Gathering data at the bwlch of Pen y Waun Fawr

There’s a surreal enjoyment that can be found with surveying a road.  It can be dangerous, to the person conducting the survey as well as to the equipment as evidenced by the unfortunate dicing with death the Trimble experienced when it was run over.  However, the Trimble is a sturdy beast and I’ve learnt from past experience, and now come well prepared with a car roof and surveying steps.  The surreal quality still remains though, and this kind of activity is not one that I envisaged being a part of my life even a few years ago.

Done the job and now ready to be packed away

Once allotted data were gathered and stored I closed the equipment down, took a few photos, packed it away and headed down to Bontdolgadfan and the hill road toward Talerddig where the high point of the road nestled beside a field where the next roadside survey was to take place.  

Survey Result:

Pen y Waun Fawr

Summit Height:  401.3m (LIDAR)

Summit Grid Reference:  SN 87843 94922 (LIDAR)

Bwlch Height:  330.1m (converted to OSGM15, Trimble GeoXH 6000)

Bwlch Grid Reference:  SN 88483 94552 (Trimble GeoXH 6000)

Drop:  71.2m (LIDAR summit and Trimble GeoXH 6000 bwlch)

Dominance:  17.74% (LIDAR summit and Trimble GeoXH 6000 bwlch)

  

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Trimble Surveys – Pumlumon

13.09.19  Bryn Amlwg (SN 921 973), only bwlch surveyed

Beyond the gate is the bwlch of Bryn Amlwg

Bryn Amlwg is a great bulk of a hill whose summit now has wind turbines scattered across it.  These are a part of the Carno wind farm which was first installed in 1996 with 56 wind turbines.  The Carno II project extended the number to 68 with the new turbines reaching a tip height of 80m.

I’d visited the summit of Bryn Amlwg on one previous occasion, in October 2013.  I found the approach from the east to be attractive, and although the vast upland area of this hill still gives distant views any semblance of tranquillity it once had is now replaced by the hummed thud of turbine blades.

The trig pillar and wind turbines at the summit of Bryn Amlwg

Bryn Amlwg is a relatively prominent hill, and as such is listed as a Marilyn and Lesser Dominant.  Today it was its connecting bwlch and not its summit that I wanted to survey.  This point had already been LIDARed by Aled Williams, but as I had enjoyed a morning of breakfast at Suzanne’s, a visit to Lisa’s and catch up with Eryl and Rita in Llanidloes; this hill’s bwlch was just a few miles away and would form the first of six such surveys during the remainder of the day.

The bwlch of Bryn Amlwg is placed to the south-west of its summit in a closely cropped field next to a minor road and beside the drive that leads to a house named Hirnant.  Having knocked on the front door and received no reply I drove back down the drive and parked beside the minor road.  As I stepped out of my car a post van drew up, I explained what I wanted to do and the postman said that the field probably wasn’t a part of Hirnant’s land and that he was sure nobody would mind me wandering around in it for a few minutes.

The gate giving access to the field was only a few metres from where I had parked my car and I was soon walking on the cropped grass beside the mature boundary hedge which kept the minor road at bay.

The land gently ebbed upward to where the critical point lay; it then gently ebbed downward in a more confident fashion.  The point where each met was relatively easy to pinpoint and having the ten figure grid reference produced by Aled’s LIDAR analysis zeroed me in toward the critical point.

Once the Trimble was positioned atop my rucksack and the measurement offset between its internal antenna and the ground below was noted, I set it to gather data and stood back in the early afternoon sunshine.

Gathering data at the bwlch of Bryn Amlwg

The Trimble GeoXH 6000 set-up position at the bwlch of Bryn Amlwg

Five minutes data collection soon passes, and today I stood and looked out on a vividly greened and manicured field that blazed its way in to the almost iridescent blue above.  Both colours screamed out in unison.

Once data were gathered and stored I packed the Trimble away, turned and retraced my way back to the access gate, not a thing had stirred at Hirnant.  My next bwlch survey was only a short drive on the minor road and connects to the Pedwar of Pen y Waun Fawr (SN 878 949).  

Survey Result:

Bryn Amlwg

Summit Height:  488m (spot height)

Summit Grid Reference:  SO 92161 97346 (hand-held GPS via DoBIH)

Bwlch Height:  318.7m (converted to OSGM15, Trimble GeoXH 6000)

Bwlch Grid Reference:  SO 87945 93874 (Trimble GeoXH 6000)

Drop:  169m (spot height summit and Trimble GeoXH 6000 bwlch)

Dominance:  34.68% (spot height summit and Trimble GeoXH 6000 bwlch)

  

For further details please consult the Trimble Survey Spreadsheet