Mapping Mountains – Trimble Surveys – Fforest Glud and Hirddywel

26.07.18  Great Rhos (SO 182 638, bwlch only [SO 177 718]) and Pegwn Mawr (SO 023 812, bwlch only [SN 926 800])

It was only a short walk down a vehicle track heading toward the rail line through the parched land of a field to where I wanted to gather Trimble data from.  Thankfully all was quiet as I went about my business; I had consulted the timetable before deciding which bwlch to survey first and no trains were planned to use this track for the next 80 minutes.  However, as I placed the Trimble atop my rucksack to give it elevation above its immediate surrounds and measured the offset between its internal antenna and the ground below, I was conscious that I should not linger.

The vehicle track leading down toward the rail line

Thankfully the Trimble attained its 0.1m accuracy level before data should be logged in the customary quick way, and once it was activated to gather data I stood back and counted the seconds to when the allocated five minutes of data were collected and stored.  I then switched the equipment off, took a number of photographs from different directions and packed the Trimble away, gathered up my rucksack, and opened the gate giving me access back in to the field leading toward my car.

Gathering data at what proved to be the critical bwlch of Great Rhos

Once on the minor lane I walked past my car and up the track toward Maylord farm as I wanted to gather a data set from where the current listed position of this bwlch is given, and even though this was visually much higher on the hill to hill traverse it would complete all necessary surveys for this bwlch position.

The Trimble set-up position for the second survey at the southerly bwlch

The critical point of this higher position is placed beside the gravel track leading to Maylord farm, and as the Trimble beeped away in the morning sunshine I gained height to its north-east and took a series of photographs looking back down on its position, that of my car and the rail line below.  Once five minutes of data were gathered I closed the Trimble down, packed it away and headed back to my car for the drive north to the outskirts of Llangurig where the northerly bwlch is placed.

Gathering data for the second position at the southerly bwlch

LIDAR covers this northerly bwlch although its analysis is not as easy as many other bylchau I have looked at over recent months, the reason for this is that the A 470 road has elevated the ground it is built on and the disused railway has created a cutting.  However, extensive LIDAR analysis led me to believe that the natural bwlch is still intact and I came prepared with three ten figure grid references and their respective heights produced by LIDAR analysis. 

LIDAR image of the northern bwlch

The first position to survey was where LIDAR places the natural bwlch, the second is a remaining natural bwlch that is higher on the hill to hill traverse and therefore not the natural bwlch, with this second point having been recently terra-formed by the introduction of wide gravelled tracks, and the third position is where the valley to valley traverse meets in the railway cutting.

I parked on the wide gravelled track which heads up toward Maesgwyn farm, from here a public footpath heads across the field to where the natural bwlch is positioned, as I was entering the field a large wagon chugged its way down the gravel track and stopped beside my car and the diver shouted over that it was best that I park in the near lay-by as vehicles would be using the track during the next few hours, I duly moved my car and proceeded to walk back on the road to gain access to the gate leading in to the field.

By now the sun was increasing in strength and even though all I did was walk on relatively level ground it brought beads of sweat to my brow, the blue of the sky was radiant above and as I went about this next series of surveys, cars hurtled past on the A 470, all blissfully unaware of the unusual proceedings being conducted in the field next to the road!

The ten figure grid reference produced by LIDAR analysis zeroed me in to the critical and natural bwlch and once the Trimble had been set up I gathered 11 minutes of data.  I was not the only one in the field as a herd of cows were slowly grazing their way toward where the Trimble was placed, thankfully none came too close and the survey proceeded without any difficulty.

Gathering data at what proved to be the intact natural and critical bwlch of Pegwn Mawr

LIDAR analysis also indicates that there is another remaining natural bwlch that is higher on the hill to hill traverse and therefore not the natural bwlch, and whilst here I thought I should also gather data from this second point, which I duly did.  This second point is where ground has recently been disturbed through the construction of either a new track or the widening of existing tracks, and another five minutes of data were gathered from this position.

Gathering data for the second position at the northerly bwlch

All that remained was to gather a data set from the disused rail cutting; thankfully a gate gives easy access to this from the main road close to where my car was parked.  And again the ten figure grid reference obtained from LIDAR analysis directed me to the critical point, as this was deep in an overgrown cutting I decided that 15 minutes of data should be gathered, and whilst the Trimble did its stuff I tried to persuade one of three grazing cows that it did not want to eat the Trimble, thankfully once it had taken a few unwelcome steps toward it my encouragement not to come any closer seemed to do the trick and it gently backed away to continue chomping on grass.

The Trimble being eyed up by an inquisitive cow in the overgrown remains of the railway cutting

Gathering data for the third position at the northerly bwlch

As the Trimble gathered this last data set of the day I sat on a grassed hummock and watched the three cows whilst luxuriating myself in the warmth of the morning.  Once 15 minutes of data were gathered and stored I headed back to my car and called on good friends in Llanidloes; Eryl and Rita, to sit in the sun for a number of hours catching up with conversation and enjoying a lovely lunch, an excellent end to a good morning’s surveying.

Survey Result:

Great Rhos

Summit Height:  659.9m (converted to OSGM15, from subsequent Trimble GeoXH 6000 survey)

Summit Grid Reference:  SO 18213 63896 (from subsequent Trimble GeoXH 6000 survey)

Bwlch Height:  281.3m (converted to OSGM15)

Bwlch Grid Reference:  SO 17776 71803

Drop:  378.6m

Dominance:  57.38%

Pegwn Mawr

Summit Height:  585.3m (converted to OSGM15, average of two subsequent Trimble GeoXH 6000 surveys)

Summit Grid Reference:  SO 02391 81239 (from subsequent Trimble GeoXH 6000 survey)

Bwlch Height:  285.9m (converted to OSGM15, natural bwlch)

Bwlch Height:  283.8m (converted to OSGM15, disused rail cutting)

Bwlch Grid Reference:  SN 92693 80074 (natural bwlch)

Bwlch Grid Reference:  SN 92601 80035 (disused rail cutting)

Drop:  299.3m (natural bwlch)

Drop:  301.5m (disused rail cutting bwlch)

Dominance:  51.14% (natural bwlch)

Dominance:  51.51% (disused rail cutting bwlch)

For an in-depth examination of these two hills and their respective bylchau

For details on the 1st summit survey of Pegwn Mawr

For details on the 2nd summit survey of Pegwn Mawr

For details on the summit survey of Great Rhos

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Trimble Surveys – Fforest Glud

06.10.17  Carneddau (SO 076 543), Carneddau (SO 069 551), Carneddau (SO 063 545), Carneddau (SO 066 540), Caer Fawr (SO 058 530) and Caer Einion (SO 063 530)

Carneddau (SO 063 545)

The land heading north-east from the town of Llanfair-ym-Muallt (Builth Wells) has three distinct and compact hill ranges, with the Llandegley Rocks furthest north-east, Gilwern Hill in the centre and the Carneddau in the south-west.  Over recent weeks I’d visited the Llandegley Rocks and Gilwern Hill area, today I wanted to complete these three compact hill groups and visit the Carneddau.

I parked outside Upper Pentre having chatted with the young farmer who had come out to see what I was up to, he had confirmed, as others had done before him that the hills that hill baggers consider as separate entities are just part of the one hill known locally as the Car-neth-ee hill.

As I wandered up the remaining steep and narrow lane to the last farm house; Rhiwlas, the sun had appeared over the shoulder of Aberedw Hill and the trees and undergrowth beside the lane were illuminated in early autumn colour, this shone and almost sparkled in intensity as a clean and low sun did wondrous things to the quiet and peaceful surrounds.  Down in the valley to the east the last throngs of mist were clinging to dew soaked fields as sheep scattered hillsides grazed nonchalantly.

Early autumnal colour

Early morning mist still clinging to a dew soaked valley

My first surveying objective was positioned in a reed infested bog, not the worst of the day by any means, but a foretaste of what was to come, this bwlch is connected to a 376m map heighted hill which stood out above me and to my north-east, elongated in shape and partly silhouetted by the low sun, once bwlch data were stored I walked to its summit.

Gathering data at the critical bwlch of the first of the Carneddau hills (SO 076 543)

The summit proved a tremendous vantage point to pick out the others hills I planned on visiting during the day, with the bulk of the highest of these Carneddau hills showing its attractive south-eastern side with a distinctive crag dropping to slopes of green grazed grass and dulled bracken below.

The south-eastern side of the highest of the Carneddau hills (SO 069 551)

Gathering data at the summit of the first of the Carneddau hills (SO 076 543)

After the Trimble was packed away I back-tracked toward the bwlch and picked up a path through bracken to the lower part of land below the crag.  Above me early morning grey cloud banks accentuated the vivid blue of an otherwise clear sky.  I chose a path that circumvented the crag on its west and continued up to the land beyond and leading to the high point of the day’s walk.

The fourth of the Carneddau hills (SO 066 540) 

In the distance an occasional loud cry of a farmer out on the hill meandered across the land, and although the person’s voice floated in the breeze I could not pinpoint where it came from, as I gained height the delicateness of grass fixed my concentration, with each thin stem seemingly dancing as it swayed to and fro as a morning westerly breeze gave solace from the early autumn warmth of clear skied sunshine.

Looking across at Castle Bank (SO 087 561) a hill I'd surveyed a few weeks before

The third of the Carneddau hills (SO 063 545)

Looking back on the hill I'd just surveyed; the first of the Carneddau hills (SO 076 543)

I’d come prepared with a series of ten figure grid references produced by Aled from his LIDAR data analyses and these helped in pinpointing set-up positions at a number of summits and bylchau during the walk, and the summit of the highest of the Carneddau proved to be 3 metres from where a few stones mark what many believe to be the high point of the hill.

Gathering data from the summit of the highest of the Carneddau hills (SO 069 551)

I’d visited the Carneddau once before with three friends when we had traversed from north to south and remember being impressed by their openness and solitude, and now many years later I was back and looking out from their highest summit to an open and bewitchingly peaceful land of rounded summits, occasional rock outcrop and greened paths leading this way and that amongst brackened slopes, but above all it was the openness of the hill that I found appealing.

The distant Caer Fawr (SO 058 530)

The next two Carneddau hills (SO 066 540) on the left and (SO 063 545) on the right

The next summit lay south-west and is adorned by a trig pillar, on the way I surveyed its connecting bwlch and again the LIDAR data produced by Aled zeroed me in to its correct position.

Gathering data at the critical bwlch of the third of the Carneddau hills (SO 063 545)

This next Carneddau hill has a northerly top which is given a 435m spot height on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website and as the trig pillar is given a 436m height I wanted to gather data from each, and duly did, with the view from beside the trig being particularly impressive, this is also where the ashes of Albert George New were scattered, and a small unobtrusive plaque commemorates the detail, Albert had chosen a beautiful place to be beside.

Gathering data from the northerly top of the third of the Carneddau hills (SO 064 548)

Gathering data from the summit of the third of the Carneddau hills (SO 063 545)

A fence led down to the next bwlch and as the Trimble gathered its customary five minutes of data I spotted two people heading toward the high point of the Carneddau, the only walkers I saw all day.  This bwlch proved to be another delightfully quiet spot amongst the hills, an undisturbed place of green grass and dulled bracken.  A number of paths led up the opposing hill side heading through bracken to the gentler high green slopes above.

The highest of the Carneddau hills (SO 069 551)

Gathering data from the critical bwlch of the fourth of the Carneddau hills (SO 066 540)

The highest of the Carneddau hills (SO 069 551)

The third of the Carneddau hills (SO 063 545) with its northern top on the right

The summit of the last of four individual hills that form the larger Carneddau hill has a large cairn and a hollowed out wind shelter on top, I examined the lay of land from a number of directions and prodded at a number of rocks that all vied for the high point of the hill, choosing one that didn’t move I set the Trimble up aligned with the rock’s high point with the equipment balanced on my rucksack.  Five minutes later I closed it off, packed it away and headed down toward a fence and wall which led to the next bwlch of the day.

Gathering data at the summit of the fourth of the Carneddau hills (SO 066 540)

By now the clear blue skies of the morning were quickly overtaken with high cloud hazing the sun and dulling the colour.  My next hill had an individual name; Caer Fawr, and it stood out robust and squat with the wall I was following striding out confidentially straight down toward its connecting bwlch.

My last hill of the day; Caer Einion (SO 063 530)

Caer Fawr (SO 058 530) with the distinctive square blocked conifer plantations of Mynydd Epynt in the background

The fourth of the Carneddau hills (SO 066 540)

As I approached its connecting bwlch I stopped to admire a standing stone now incorporated within a boundary of fences with barbed wire wrapped around it on one side.  It is an impressive silent monolith.

The monolith

Walking toward this next bwlch it was evident that is was somewhere beside a large reddened and decidedly horrible looking bog, as I approached I muttered that I would not be going in to that and made a mental note to avoid it at all costs, ten minutes later and I was venturing in to its wobbly domain.  However, upon processing this data I had misread the ten figure grid reference Aled had produced from LIDAR data and I was now heading in to a huge blanket bog thinking I was heading for the critical bwlch of the hill, and unknown to me I had read the co-ordinates incorrectly and would end up 100 metres from where I should have been, to confound this, the critical bwlch was behind me on dry ground.

The whole area was a blanket bog and oozed methane as I tried not to succumb to its foul smelling depths, I tottered from one water laden tussock to another as each footstep moved all the land around me, it was like walking on an expansive water bed.  I eventually zeroed in to the misread grid reference produced by LIDAR and tried to find semblance of dry ground to wait for the allotted five minutes of data collection.  I was thankful to leave the blanket bog intact.

Gathering data at what I thought to be the critical bwlch of Caer Fawr

Leaving the bog, a path led up to the northern slopes of Caer Fawr, I slowly plodded up to the summit of the hill, which is crowned by an attractive rock outcrop merging in to its greened surrounds; I set the Trimble up aligned with its high point and waited for the allotted datum points to be stored.  I now had a chose whether to visit Caer Einion or to make my way back contouring the hill toward my inward route; I smiled when I thought of this chose as I knew I would visit this last hill.

The Carneddau from the approach to Caer Fawr

Gathering data at the summit of Caer Fawr (SO 058 530)

Caer Einion is only small in prominence and the lowest in height that I would visit during the day, but it is attractive in profile and commands the southern lands of the Carneddau, its defensive embankments and ditches form small ramparts leading down to its connecting bwlch.

Caer Einion (SO 063 530)

After descending the north-eastern slopes of Caer Fawr I followed a sheep path toward the last bwlch I wanted to survey during the day, this was positioned on grass beside bracken, and as the Trimble gathered data I looked down on my outward route and contemplated the best way of getting there.

Gathering data at the critical bwlch of Caer Einion

The summit of Caer Einion is crowned by a low lying small rock outcrop and again as the Trimble gathered its data I tried to decide which option was best for my descent.  Once the Trimble had done its stuff I headed back to the connecting bwlch and descended west to where a footpath is marked on the map.  To get to it I slowly stumbled my way through head high bracken as the sun again made an appearance through thinning high cloud.  The going proved slow and pathless but eventually I popped out on an old green track of sorts which gained height above Graig-ddu and immerged close to Hendre-einon, here I stopped to talk with the occupant of each and passed away a contented 20 minutes or so in the afternoon sunshine as Ann told me about her life and living in Graig-ddu, she was a seeker of quiet surrounds and a life unencumbered, she had found it and as I waved my goodbyes there was a part of me that envied her lifestyle, but also relished the thought that she had found what she wanted.

Gathering data at the summit of Caer Einion (SO 063 530)

Caer Fawr (SO 058 530)

The footpath beyond Hendre-Einon led across forgotten fields to a small foot stile and planked crossing of a ditch back toward Upper Pentre where my car was parked.

The Carneddau did not disappoint, and the memory of all those years ago when I first visited still remains, they are stunning open hills with a solitude and peacefulness to be savoured.                 

Survey Result:

Carneddau (significant name change)

Summit Height:  375.0m (converted to OSGM15)

Summit Grid Reference:  SO 07652 54311

Bwlch Height:  344.7m (converted to OSGM15)

Bwlch Grid Reference:  SO 07300 54197

Drop:  30.3m (Sub-Trichant reclassified to Trichant)

Dominance:  8.08%

Carneddau

Summit Height:  443.8m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SO 06991 55194 (Trimble GeoXH 6000)

Bwlch Height:  237.6m (LIDAR)

Bwlch Grid Reference:  SO 07153 55931 (LIDAR)

Drop:  206.2m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  46.47% (Trimble GeoXH 6000 summit and LIDAR bwlch)

Carneddau (significant name change)

Summit Height:  435.8m (converted to OSGM15)

Summit Grid Reference:  SO 06304 54532

Bwlch Height:  399.3m (converted to OSGM15)

Bwlch Grid Reference:  SO 06652 55124

Drop:  36.5m

Dominance:  8.36%

Carneddau (significant name change)

Summit Height:  430.7m (converted to OSGM15)

Summit Grid Reference:  SO 06627 54067

Bwlch Height:  390.7m (converted to OSGM15)

Bwlch Grid Reference:  SO 06552 54519

Drop:  39.9m

Dominance:  9.27%

Caer Fawr

Summit Height:  393.1m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SO 05818 53082 (Trimble GeoXH 6000)

Bwlch Height:  356.3m (LIDAR)

Bwlch Grid Reference:  SO 05954 53561 (LIDAR)

Drop:  36.8m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  9.37% (Trimble GeoXH 6000 summit and LIDAR bwlch)

Caer Einion

Summit Height:  350.9m (converted to OSGM15)

Summit Grid Reference:  SO 06356 53057

Bwlch Height:  335.1m (converted to OSGM15)

Bwlch Grid Reference:  SO 06341 53177

Drop:  15.8m

Dominance:  4.51%

For further details please consult the Trimble Survey Spreadsheet