Mapping Mountains – Trimble Surveys – Gwaun Ceste

10.08.23  Little Hill (SO 171 537, only bwlch surveyed) and Gwaun Ceste (SO 158 555) 

Gwaun Ceste (SO 158 555)

Over recent years LIDAR has resulted in many hill reclassifications, it is not overstating to say that the use of LIDAR has revolutionised hill classification.  It is also responsible for many summit relocations, and today it was a potential summit relocation that I wanted to investigate with the aid of the Trimble GeoXH 6000 in hand.

The hill in question is Gwaun Ceste, which I had visited on two previous occasions, the last of which was in July 2015.  I had then taken data from the high point beside the triangulation pillar, which consists of a patch of grass encircling the trig beside a morass of moorland, mainly consisting of heather.  It was this position that was then recognised as the high point of the hill.  However, LIDAR gives another position 0.26m higher than the data set produced by the Trimble.  This new position is approximately 180 metres to the south-east of the trig pillar, and it consists of heather. 

LIDAR summit image of Gwaun Ceste (SO 158 555)

Over recent weeks the weather had been inclement with some beautiful blue skied days interspersed amongst many wet ones; today the forecast gave for dry conditions with warm sunshine.  It was the ideal day to head up to Gwaun Ceste and take a series of data sets from these two positions.

I considered a circular walk, similar to the one I had done with Nicola Morris in 2015 when we also visited the two Pedwar hills that are named Little Hill.  However, my priority was the surveys of Gwaun Ceste and therefore I started my walk from the top of the minor road that heads from the small community of Glasgwm toward Llanfair Llythynwg (Gladestry) in the east.

After arriving and parking my car I took a series of photographs of a number of sheep, many lazing on and beside the minor road, a large tree cast shade at this time of the morning and they were happily shielded from the brightness and warmth of the sun. 

Lazy morning for the sheep

The approach to Gwaun Ceste from this direction is similar to many hills in Radnorshire as a good track gave access avoiding the moorland surrounds.  This headed around the western shoulder of the lower of the two Little Hill hills.  These tracks are a godsend as many similar heighted hills comprise moorland with rough grass but mainly heather predominating and the tracks give relatively easy access to the higher ground. 

The track heading toward Gwaun Ceste

My first task was to re-survey the bwlch of the lower Little Hill, my planned route passed over it and according to LIDAR my previous Trimble survey was approximately 30 metres from its critical point.  As I approached the bwlch the southern flank of Gwaun Ceste rose above, it looked picturesque at this time of day with blue sky above, direct sunlight on it and a foreground of purpled heather. 

LIDAR image of Little Hill (SO 171 537)

Using the Trimble as a hand-held GPS it was easy to zero in on the grid co-ordinates that LIDAR give for this bwlch.  Once at the critical point I positioned the Trimble atop my rucksack; took the measurement offset between its internal antenna and the ground at its base and once the 0.1m accuracy level was attained I set it to gather data. 

Gathering data at the bwlch of Little Hill

This was a stunningly beautiful place to be at this time of the morning.  No one else was about and with the tranquil warmth generated from the sun and just the hint of a breeze it certainly felt good to be out.  Once allotted data were gathered and stored I closed the equipment down, took a few photos, packed it away and started on the main uphill section of the day. 

The Trimble set-up position at the bwlch of Little Hill

Ahead were two main options, a steep green path that Nic and I had taken on my last visit and a track heading north-westward gaining height as it did so.  I decided on the former, with the latter hopefully found for my descent.  The continued ascent proved steep, but as ever with one or two stops to regain breath height was soon gained. 

Looking back on the bwlch area of Little Hill

The green path merged on to a track which near the LIDAR high point of the hill headed away toward the east.  It was at this point that I headed over the moor on to a series of sheep paths, the going hereabouts was never difficult and with the aid of the Trimble used as a directional device the LIDAR high point was soon reached.  This is positioned in a morass of heather, to the north-east the trig stared back at me, over such a distance it was almost impossible to judge purely by eye which point was higher. 

Gathering data at the LIDAR summit of Gawun Ceste with the trig pillar summit in the background 

I wanted to take two data sets from this position, and do likewise with the high point beside the trig pillar.  Each in relation to the other would then give a good indication of true height and importantly true summit position.  With each survey taking around ten minutes to set up and gather data, it meant I would be on the summit area for about 40 – 50 minutes.  I’ve experienced such time restraints due to surveying many times before, and these are now the norm when I go hill walking. 

The Trimble set-up position at the LIDAR summit of Gwaun Ceste

As the LIDAR summit position comprises heather I wanted to take the survey measurement down to the base of peat, on the second survey I positioned the Trimble on what looked to be the high point of this ground and found that it comprised a root ball of a clump of heather, and wondered if LIDAR had modelled this instead of the adjacent peat at its base.  The Trimble result compared to LIDAR position and height will answer this question.

Once the two data sets were gathered at the LIDAR summit I headed over to the trig pillar.  Once there I looked back on where I had just been, and again from here it was hard to judge what position was higher.  Thankfully the high point beside the trig pillar consisted of one or two slight bumps on an otherwise small area of grass and earth.  Again I took two data sets, each about a metre apart. 

Gathering data at the trig pillar summit of Gwaun Ceste with the LIDAR summit in the background

During data collection I looked at my map and followed my downward route on it toward where a footpath was indicated.  This was at a fold in the map, which wasn’t ideal.  As I hadn’t taken this route before I did not want to end up on a track losing height and ending up in the valley below.  I therefore decided to keep high on my descent and use any sheep track I could find.  In hindsight I would not recommend this. 

The Trimble set-up position at the summit of Gwaun Ceste

As data were collected beside the trig pillar I happily stood in the heather below the equipment so as not to disturb satellite reception, and scribbled all necessary information in my survey log book which will be documented at a later stage and put in the Trimble Survey Spreadsheet hosted on my Mapping Mountains site.  In the distance the peaks of Bannau Brycheiniog stood out, their blue tinged profiles easily recognisable, to my north-east the higher hills of Fforest Glud again stood out whilst to my south the bulk of the Black Mountains were a wedge of land.  Away to my west and north-west there were many hills, some I could name, but many others I could not.  I felt privileged to be out in such a place.

As the last of the individual allotted data were gathered and stored I approached the equipment and closed it down.  It was now time to head down and hopefully find a good path, this proved relatively easy to begin with as I decided to use what initially proved a good sheep path, unfortunately this all too soon petered out and my continued progress soon turned in to a slow bracken bash with some growing as high as my chest.

I found an occasional sheep path to continue on, but these soon bisected and again petered out, much of the going was pathless, some relatively easy over low moor, whilst some quite horrendous and especially with the strengthening heat which started to sap my energy levels.

I eventually emerged looking out over the connecting bwlch to Little Hill which I had surveyed earlier in the morning.  As I lost height I spotted two walkers making their way up the track I should have been on, I headed in their direction and once on the track sat to recover my breath. 

Looking across to Little Hill (SO 171 537)

From here the going down proved slow, my energy levels had plummeted which is a concern I’ve lived with for two years or more, however experience has told me to take my time and continue very slowly and this is what I did.

I was in no rush and sat and rested on another couple of occasions, the last listening to summer sounds of distant bleating sheep, the near buzzing of flies and the gentle wisp of breeze as it cascaded over the land.  Above was blue sky with dappled white and light grey of the occasional cloud, with the foreground dominated by a many hued green with the lower moor soon giving way to the customary dappled and patch-worked fields. 

Looking across at the other Little Hill (SO 142 537)

Back at the car I chatted to a couple who were resting having reached the top of the road, they were on a two day cycle ride with heavy panniers on their bikes.  Soon after they waved and headed down the road I heard the sound of a vehicle coming down the opposing track to the south. 

Aaron Brookshaw - the local Gamekeeper

The vehicle was driven by the gamekeeper to these moors, Aaron Brookshaw, after I introduced myself and explained my interest in hill names; we spoke for 10 – 15 minutes.  These unplanned encounters with people who work the land that our hills are situated on are always worthwhile.  They can give a wealth of locally known information, from feature names to the names of hills and it was no different with Aaron.  After he left, I changed and headed to Llanidloes to visit Eryl and Rita, before continuing to Newtown to watch Oppenheimer in the Regent Cinema, in all it proved an excellent way to spend the day. 

 

Survey Result:

 

Little Hill                                   

Summit Height:  469.2m (converted to OSGM15, from previous Trimble GeoXH 6000 survey)

Summit Grid Reference:  SO 17175 53749 (from previous Trimble GeoXH 6000 survey) (summit relocation)

Bwlch Height:  422.7m (converted to OSGM15)

Bwlch Grid Reference:  SO 16357 54404

Drop:  46.5m

Dominance:  9.91%

 

 

Gwaun Ceste                             

Summit Height:  542.1m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SO 15821 55547 (Trimble GeoXH 6000)

Bwlch Height:  376.9m (LIDAR)

Bwlch Grid Reference:  SO 16953 58220 (LIDAR)

Drop:  165.2m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  30.47% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

For further details please consult the Trimble Survey Spreadsheet 

Mapping Mountains – Trimble Surveys – Gwaun Ceste

 

24.06.22  Twyn y Garth (SO 107 437) 

LIDAR image of Twyn y Garth (SO 107 437)

Twyn y Garth had passed me by on many a journey as I headed south toward other hills on the A470 road.  Although I had visited its higher neighbours to the north and east, it was its inclusion in The Huws – 100 Great Welsh Hills under 2,000ft that prompted my suggestion to visit.  However, it also tied in nicely with what Aled and I planned to do with the majority of the day.  The morning of which was spent at the Crucywel (Crickhowell) archive examining historical maps and documents relating to the Black Mountains hill range.  With the archive closing at 12.30pm it gave us time to visit a hill or two in the afternoon as we headed back north.

The forecast was not conducive to hill bagging with heavy localised showers predicted and the possibility of thunder and lightning edging its way into Wales in the afternoon.  By the time we had dealt with all necessary documents at the archive centre the early morning murk that had nestled forlornly on many hill tops during our journey south, had lifted, but the grey gloom still predominated above.

The first hill we headed toward was Mynydd Llan-gors (SO 159267), as I had visited this hill on three previous occasions I waited in the car as Aled headed up, 55 minutes later and he was back at the car.  During his ascent a scud of rain passed over the land for ten minutes or so, nothing to really dampen proceedings but I wondered if this was a foretaste of what may materialise later in the afternoon.

On the drive north from Mynydd Llan-gors there was another scud of rain that again petered out after ten minutes, but the sky still remained a foreboding deep grey, with it always threatening a downpour.

There are few opportunities to park on the minor lane that heads to the north of Twyn y Garth.  We called at the two houses at the end of the lane’s paved section to ask permission to park.  No one was in, so having left a note on the dashboard explaining where we had gone, I pulled my car off the main steep gravelled track leading to each house and away we went through a gate and on to the hill.

The summit cone of Twyn y Garth rises steeply from the direction we approached, at this time of year its upper slopes were festooned in greened fern.  A conveniently placed path contoured its way beside a boundary fence heading westward, we followed this until the steep slopes above gave way to grass, and heading up at this point saved a thrash through high bracken. 

The steep slopes leading up Twyn y Garth

As we gained height the conditions became muggy, the sky to the south always threatened rain, but thankfully whilst on the hill this did not materialise.  Aled soon pulled ahead and as he disappeared over the ridge crest leading toward the high point of the hill I slowly followed.  The summit area of Twyn y Garth is encircled by the remains of an impressive ancient hill fort and I followed one of its embankments around its southern side and met Aled close to the top, he was standing beside the First World War German Field Gun that is positioned just below the high point of the hill.  This was placed on the hill in memory of the brother of Mrs Lionel Trafford and other local men who died in the 1^st World War.  I have not encountered such an object as this on any other Welsh hill.  There are more recent relics of warfare scattered on parts of Mynydd Epynt, but the placing of this German Howitzer is probably unique as a testament to lives lost during conflict. 

The 1st World War field gun positioned just below the summit of Twyn y Garth

The plaque on the field gun

Aled beside the German Howitzer

As I approached the summit, Aled joined me on top and we debated where the high point was positioned as two contenders vied for this accolade; one on the outer embankment and one on the inner embankment, with a steep ditch between.  LIDAR indicates ground on the inner embankment as higher and this is where the Trimble was set up. 

Gathering data at the summit of Twyn y Garth

As the Trimble gathered its individual datum points we stood below the equipment so as not to disturb satellite reception.  After five minutes data collection I turned the equipment off, took a few photographs and packed it away.

We quickly reversed our inward route as the sky was still threatening heavy rain.  When we arrived back at the car I checked my watch, the walk and survey had taken just 30 minutes and a few of these were spent debating where the summit was positioned! 

 

Survey Result: 

 

Twyn y Garth

Summit Height:  324.3m (LIDAR)

Summit Grid Reference:  SO 10733 43731 (LIDAR)  

Bwlch Height:  270.7m (LIDAR)

Bwlch Grid Reference:  SO 10654 43937 (LIDAR)

Drop:  53.6m (LIDAR)

Dominance:  16.53% (LIDAR)

 

 

For further details please consult the Trimble Survey Spreadsheet

 

 

 

Mapping Mountains – Trimble Surveys – Gwaun Ceste

 

17.07.21  Hergest Ridge (SO 246 557), Hergest Ridge (SO 254 562, previously Trimbled) and Hanter Hill (SO 251 570, not Trimbled) 

The Welsh summit of Hergest Ridge (SO 246 557)

The main purpose of this walk was to visit and survey the Welsh summit of Hergest Ridge, which is now classified as a Pedwar under National Top status.  The concept of National Tops is explained in a separate post and for the lists co-authored with Aled Williams affects two hills, the other is Stonewall Hill (SO 318 696) which we visited and surveyed later in the day. 

This walk would also give opportunity to visit the English summit of Hergest Ridge and extend the walk across this hill’s broad summit ridge, to a point marked with a 417m spot height on contemporary Ordnance Survey maps and then also visit the Pedwar of Hanter Hill, with this and its higher neighbour separated at the connecting bwlch by the national border between Wales and England.  As the forecast gave for extremely warm conditions we needed a relatively early start to gain the majority of height before the heat of the day struck. 

We met in Caersŵs just before 8.00am and were parked and walking by 9.00am.  I had visited these hills once before in April 2015, on that occasion I had visited the higher English summit of Hergest Ridge, and not the Welsh summit, and although taking two data sets from the summit area of Hanter Hill, I failed to survey its actual summit, which we later found to be immersed in a mass of gorse. 

Approaching the hills from the west we followed a public footpath that starts as a track leading to Upper Hanter, which was once a farm.  It was already warm and any shaded area on the track proved a welcome relief from the conditions that would increase in ferocity as the day progressed. 

The public footpath leads past the front door of Upper Hanter before continuing as a green track through a gate and then onward through copious amounts of fern.  As we walked past the house we said our ‘hello’s’ to a woman sitting in shade reading.  We chatted for a few moments before waving our goodbyes and continuing up the hill. 

On the path leading to the bwlch between Hanter Hill and the English summit of Hergest Ridge

The greened path crept up hill giving good views of our first objective; the Welsh summit of Hergest Ridge, which from this viewpoint at this time of year shone green with upper slopes of fern, middle slopes consisting of grazing fields and mature trees as foreground, it looked a good hill and one which I had bi-passed when making an ascent from the south-west during my only other visit to the English summit of Hergest Ridge. 

The Welsh summit of Hergest Ridge

The green track eventually led to the connecting bwlch between Hanter Hill and Hergest Ridge; on one side of this bwlch is Wales and on the other, England.  On my previous visit a small conifer plantation was positioned just below the bwlch, this has now gone with the trees cut down. 

Hanter Hill from its connecting bwlch

The bwlch is also the meeting point of a number of tracks; we opted for the track leading to the English summit of Hergest Ridge, leaving Hanter Hill for later.  This ascent proved warm, with the left hand side of the track giving a semblance of shade.  Reaching a T-junction of tracks we then headed south-west loosing height as we did so, aiming for the Welsh summit and leaving the higher English summit until after. 

The new Pedwar is covered by LIDAR, which Aled and I had analysed.  The summit is close to a pool, which today was almost dry with just the last remaining vestiges of water giving some respite to the sheep who visited. 

LIDAR image of the Welsh summit of Hergest Ridge (SO 246 557)

The green track leads to within a few metres of this hill’s high point which consists of a small patch of gorse and fern.  The concept of National Tops was raised a few months ago and we had debated its merits and details on a number of occasions, having done so it was good to now be here standing on the Welsh summit of Hergest Ridge. 

Aled heading toward the Welsh summit of Hergest Ridge

We quickly assessed the lay of land and having decided its high point the Trimble was soon set-up gathering data.  During data collection Aled sat on the green track whilst I stood 50 or so metres away submerged in bracken.  Once allotted data were gathered and stored the equipment was closed down, packed away and I re-joined Aled on the green track and followed him back toward the higher English summit of Hergest Ridge. 

Gathering data at the Welsh summit of Hergest Ridge

The upper part of Hergest Ridge is open and any fences that exist are few and far between.  On a clear day the hill gives excellent walking on greened tracks with extensive views south to the distinctive profile of the Bannau Brycheiniog, east to the Clee Hills and Malvern Hills, and the higher Radnorshire hills to the west and north. 

It was a joy to be back on this hill; however conditions were decidedly warm and only on occasion did a welcome cooling breeze drift across its upper slopes.  We were soon on the higher summit which today had a number of horses beside it.  These slowly moved away as we made our way to the highest rock that constitutes the summit.  It was time for a rest and a bite to eat and the rocks proved an ideal place to sit and recuperate. 

The English summit of Hergest Ridge

We had no firm plan to visit the 417m map heighted top to the north-east, but as another track headed from close to its high point down to the connecting bwlch with Hanter Hill we decided to continue on the main ridge toward it. 

This top is crowned by nine monkey puzzle trees which are an unusual adornment for any summit at this altitude in this country.  Two benches are placed on their periphery and the larger gave another opportunity to sit and rest.  Just below the summit is the Whet Stone, which is marked on the map.  The stone is large, but is not Neolithic and in all likelihood found its way to its present position naturally. 

Monkey Puzzle trees at over 400m

From here it was only a short distance down the track to the bwlch between Hanter Hill and Hergest Ridge.  This bwlch has been Trimbled and LIDARed, therefore a second data set was unnecessary, however I hoped to take a data set from the true summit of Hanter Hill; something I failed to do on my previous visit. 

Hanter Hill from near the Whet Stone

The path leading up Hanter Hill proved a hot plod.  I watched as Aled quickly pulled ahead.  I paced myself going up, stopping once to take on water, look at the expanding view and to take a few photographs.  Soon I reached the hill’s summit area. 

On my previous visit I had taken two data sets from the summit area of Hanter Hill, neither of which matches the position of the summit produced by LIDAR.  This position is submerged in gorse.  As I recovered a modicum of breath I watched as Aled approached the gorse and headed in to it.  I soon followed but wearing shorts later emerged scratched and bloodied, with thorns still sticking in my legs. 

LIDAR image of Hanter Hill (SO 251 570)

When at the high point the gorse proved so dense that when I placed the Trimble on top of it, it remained in place.  Because of this I wondered about gathering data, but the thought of kneeling to take a measurement offset, coupled with four journeys in and out of the gorse waiting for the Trimble to achieve its 0.1m accuracy level before data should be locked and then waiting for allotted data to be gathered was enough to discourage me – LIDAR would suffice! 

The Trimble GeoXH 6000 at the summit of Hanter Hill

We now headed down to the bwlch and followed the green track of our ascent route back to Upper Hanter where the woman; Janet van der Linden, was still outside enjoying the morning’s shade.  We stopped and chatted, I joked that we had wondered if on our return we would be met with glasses of lemonade.  She smiled and went inside and brought out a jug of cold water with two glasses. 

A welcome sight; Janet with fresh chilled water

The water was refreshing and from a spring, it was very welcome.  We chatted about the old farm house and the route we had taken and where we were now heading.  This proved a much needed rest as even walking down hill in the increasing warmth proved tiring.  Having thanked Janet we headed down the continuation of the green track to the awaiting car and then headed northward toward Presteigne, where we stopped and replenished with goodies from the local Spar, before joining up with a narrow lane heading toward The Warren and Stonewall Hill, the latter our second Nation Top of the day. 

 

Postscript: 

Since the survey of these hills full LIDAR coverage is now available.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height and positional data that is now freely available for England and Wales.  Consequently the numerical details for these hills have been analysed using this technique, resulting in the LIDAR height and position for some of these hills being prioritised in preference to that produced by the Trimble GeoXH 6000.

Survey Result: 

 

Hergest Ridge

Summit Height:  401.0m (converted to OSGM15, Trimble GeoXH 6000) (Pedwar addition under National Top status)

Summit Grid Reference:  SO 24693 55769 (Trimble GeoXH 6000)

Bwlch Height:  269.5m (LIDAR)

Bwlch Grid Reference:  SO 22053 55707 (LIDAR)

Drop:  131.5m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  32.80% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

Hergest Ridge

Summit Height:  426.9m (converted to OSGM15, from previous Trimble GeoXH 6000 survey)

Summit Grid Reference:  SO 25435 56259 (from previous Trimble GeoXH 6000 survey)

Col Height:  269.5m (LIDAR)

Col Grid Reference:  SO 22053 55707 (LIDAR)

Drop:  157.4m (Trimble GeoXH 6000 summit and LIDAR col)

Dominance:  36.88% (Trimble GeoXH 6000 summit and LIDAR col)

 

 

Hanter Hill

Summit Height:  415.0m (LIDAR)

Summit Grid Reference:  SO 25199 57096 (LIDAR)

Bwlch Height:  346.9m (converted to OSGM15, from previous Trimble GeoXH 6000 survey)

Bwlch Grid Reference:  SO 25392 56820 (from previous Trimble GeoXH 6000 survey)

Drop:  68.1m (LIDAR summit and Trimble GeoXH 6000 bwlch)

Dominance:  16.41% (LIDAR summit and Trimble GeoXH 6000 bwlch)

 

 

For details on the survey of the English summit of Hergest Ridge and the bwlch survey of Hanter Hill

For further details please consult the Trimble Survey Spreadsheet