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