Mapping Mountains – Trimble Surveys – Banc Llechwedd Mawr

 

03.09.25  Twyni Mawr (SN 606 938) 

Twyni Mawr (SN 606 938)

Blanks on the map can be interesting to investigate.  These are the places that Ordnance Survey designate in flux, as in the ground they inhabit is unstable.  These include quarries, landfills and other places terra-formed by human interference.  However, they also include places that have not been altered by man’s need to make big holes or bury a lot of stuff in the ground. 

The blank on the map

Nowadays other online mapping show contours for such places, this gives perspective to the lay of land.  Today I was visiting friends and if the weather acted kindly we planned on visiting one of these blanks on the map.  I mention the weather as leaving Welshpool and driving west the cloud base soon closed in with drizzle becoming ever more present.  Approaching the coast this turned into heavy showers with the narrow roads leading to Ynys-las becoming water-logged.  I suppose after an unseasonably warm summer, a bit of rain was a change! 

Extract from the interactive mapping hosted on the WalkLakes website

I was heading to the Searivers Caravan Park, where Eryl and Rita were enjoying a few days relaxation, including coastal walks between what was proving to be a particularly wet spell of weather. 

The Searivers caravan site at Ynys-las

By the time I pulled up outside their home from home the rain was bucketing down, so much so that I ran from the car to the front door and hoped it was opened without delay.  The next hour or so I was very happily settled on a chair, with a mug of tea and assorted biscuits at hand as we caught up with all manner of things, whilst the rain continued to fall.  As time progressed a glimmer of semi-brightness appeared out to sea, this quickly pushed inland and heralded a tempting flash of sunlight as the rain calmed its deluge.  Rita said; ‘right if we’re going to go we need to get ready and make the most of whatever dry spell we have’.  This we did, and soon were walking through the site toward the narrow dead end road and the gate on its opposite side which gives access to the complex of dunes.

Prior to my visit I’d examined this blank on the map via LIDAR, building up the coloured contours until the high point and the connecting bwlch of these dunes was found.  LIDAR gives this point as having 18.4m of drop, so it easily qualifies as a Welsh P15, whilst maps record the name of Twyni Mawr for this area, which is apt as a translation of this can be big dunes. 

LIDAR summit image of Twyni Mawr

Whatever the occasion it’s always good to see Eryl and Rita, whom I’ve shared so much with over the years, especially so with Eryl; including travelling and treks around the Alps, Nepal, Tibet, Vietnam and Cuba, nowadays our ambitions are reduced, but the friendship is still strong. 

Information board at the access to the dunes

Our access to the high point of Twyni Mawr was via a wooden walk way which continues to the coastal sands and the sea beyond; where the walk way crests the dunes a convenient bench had been installed.  Not surprisingly this point gives extensive views out to sea and also inland to what today were cloud enshrouded hills.  Although the view was to be admired the cloud out to sea looked like more showers were on their way, so not lingering I followed Eryl as he started down the walk way whilst suggesting the best way to the high point of the dunes was to cut back using one of many valleys that interweave amongst the dunes.  Eryl had investigated some of these and cautioned that when in them it’s hard to know where exactly you are. 

The wooden walk way heading into the dunes

The path beyond the high point of the wooden walk way

Leaving the walk way we headed into the dunes and accessed the valley directly below the western flank of the high point.  It was here that Eryl stayed, watching me and Rita as we headed the short distance across the valley to the base of the steepening dune.  

The valley leading to the high point of Twyni Mawr.  Photo: Eryl Selly

Heading toward the summit of Twyni Mawr.  Photo: Eryl Selly

I’d brought an umbrella, which is a norm for me even on some higher hills, as if confronted by rain it can shield my camera equipment much better that a Goretex coat, and although it was never used today as whatever rain did come across was never heavy enough to seek protection, it proved an ideal replacement for a walking pole for Rita, who used it to steady herself as we slid ourselves uphill on the steepening sand dune.

Once at the top of the steep bit it was only a short walk on a narrow path across the ridge of the highest dune to its summit.  Here we posed for the customary photographs before continuing on the narrow ridge path back toward where Eryl was patiently waiting for us on the wooden walk way. 

At the summit of Twyni Mawr.  Photo: Rita Selly

Heading back to the caravan the whole adventure had only taken 55 minutes, and we were ever so lucky with the weather as only a skidding light shower had blown across the land whilst on the dunes, which was fortunate considering how heavy the showers had been on my way toward Ynys-las and on my arrival.

We ended the day with a trip into Aberystwyth for a lunchtime meal at the University Art’s Centre before settling down to watch The Roses in the cinema.  It even brightened up for our drive back to Ynys-las and my continued journey to Welshpool.  It proved an excellent day out. 

 

Survey Result: 

 

Twyni Mawr 

Summit Height:  22.8m (LIDAR) (significant height revision)  

Summit Grid Reference:  SN 60614 93828 (LIDAR)

Bwlch Height:  4.4m (LIDAR)

Bwlch Grid Reference:  SN 60576 92484 (LIDAR) 

Drop:  18.4m (LIDAR) (Welsh P15 addition)

Dominance:  80.55% (LIDAR)

 

 

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Trimble Surveys – Banc Llechwedd Mawr

09.07.22  Banc yr Ŵyn (SN 741 902) 

Banc yr Ŵyn (SN 741 902)

The only time I had visited this hill was 22 years ago in August 2000, during a four hill Dewey walk taking 2 hours 50 minutes.  I have slowed since those heady days when hills were easy affairs to get up.  Nowadays my hill walking is more circumspect, with route, distance and amount of ascent being factors that all too easily keep me away from the higher hills.  Although my pace has slowed, the fact that I’ve visited the higher Welsh hills on a multitude of occasions is also a determining factor and as I always enjoy venturing on to new ground, it is always a pleasure to visit new hills.

Earlier in the morning Aled and I had visited Disgwylfa Fawr (SN 737 847) and Disgwylfa Fach (SN 756 838).  By the end of the walk the conditions were warming to an uncomfortable degree, therefore the hills we planned on now visiting consisted of small walks and we chose wisely with an ascent of Banc yr Ŵyn from the convenience of its forest track to the north proving ideal as my last walk of the day.

It took a long time to drive from the track beside Llyn Syfydrin to the track heading toward the forestry that surrounds Banc yr Ŵyn.  However, the land hereabouts is stunning in its simplicity with openness predominating, with lakes and hills adding depth and perspective to the landscape.

Having driven on the track leading in to the forestry Aled navigated as I continued toward the junction of tracks with a narrower one leading south toward the summit of the hill, it was here that we parked.

Leaving the car we followed the track as it headed confidently southward, gaining height through dappled light that cast down from a deep blue sky.  The track soon led toward the upper, open hillside and nestled its way on the eastern side of the summit ridge before reaching close to the high point of the hill. 

LIDAR image of Banc yr Ŵyn (SN 741 902)

Prior to visiting the hill Aled and then I had LIDARed it.  The bwlch only has partial LIDAR coverage with its critical point just missing LIDAR.  However, its summit is covered and as the area taking in its high point consists of long grass at this time of year I knew it would be all too easy to miss the exact high point with the Trimble placement. 

Heading up the track leading to the summit

Gathering data at the summit of Banc yr Ŵyn

I soon had the Trimble set up gathering summit data and joined Aled sitting in thick grass looking out toward the Sub-Pedwar of Castell, which now has its upper section felled of conifers.  It looked a fine hill from this direction.  It was good to rest and enjoy the brisk breeze as it skimmed across the upper hill.  For me the uphill of the day was now over, which was a relief as conditions were decidedly warm and would continue to be so for a number of hours to come. 

Castell from Banc yr Ŵyn

Approaching the car at the end of another good, albeit hot day on the hill

Once the Trimble had gathered its allotted data I switched it off, took a few photographs and packed it away.  Leaving the summit we reversed our inward route down the track to the awaiting car.  It had been good to be out in blissful sunny conditions, with the hills chosen just giving enough for the day, without the warming conditions becoming too torturous. 

 

Survey Result: 

 

Banc yr Ŵyn

Summit Height:  501.7m (LIDAR)

Summit Grid Reference:  SN 74195 90213 (LIDAR)

Bwlch Height:  c 428m (interpolation)

Bwlch Grid Reference:  SN 74031 90845 (interpolation)

Drop:  73.7m (LIDAR summit and interpolated bwlch)

Dominance:  14.69% (LIDAR summit and interpolated bwlch)

 

 

For further details please consult the Trimble Survey Spreadsheet

 

 

 

  

Mapping Mountains – Trimble Surveys – Banc Llechwedd Mawr

 

09.07.22  Disgwylfa Fawr (SN 737 847) and Disgwylfa Fach (SN 736 838) 

Disgwylfa Fawr (SN 737 847)

As the forecast gave for particularly warm conditions from late morning on, we had a relatively early start having driven down the track leading to Llyn Syfydrin.  This lake is positioned in the heartland of the Pumlumon range and gives easy access to Disgwylfa Fawr and its adjacent hills.  We planned on visiting two hills on this first walk of the day.  However, there are a number of P30s in this area, many of which can be combined during extended walks via connecting tracks through quiet, almost forgotten land. 

Llyn Syfydrin

Intermittent cloud gave some respite from the sun as we left the car and made our way on the track leading toward the old building of Syfydrin.  Before reaching this we branched leftward on another track; unmarked on my map, which steadily gained height before levelling off.  This approach headed direct toward the western flank of Disgylfa Fawr, a hill I had only visited once before in March 2003, when along with Eryl and Stephen we visited six hills during a 5 hour 15 minute walk starting from the western shore of the Dinas Reservoir.  On this first visit this land left me with an impression of openness and wildness, with bleached moor and remains of old farm houses adding a feeling of abandoned tranquillity. 

Aled heading up the steep slopes of Disgwylfa Fawr

Nowadays earthen tracks indicating the off road use of trail bikes gauge part of this land and two of these tracks led steeply up the western flank of Disgwylfa Fawr.  I put my head down and ever so slowly started on the steep uphill plod, whilst Aled wisely took a route contouring up and waited for me at the top of the steep section.  Occasionally I rested, turned and looked down toward the lake and the continuation of land as it headed westward toward the sea, which this morning crested the horizon, temptingly blue with its straight lined edge piecing the point between sea and sky. 

Taking a rest whilst on the steep section

Once over the steepest section I followed Aled as he headed toward the summit of the hill, which is crowned with a small cairn.  The views from this vantage point are extensive and whilst I set the Trimble up to gather data, Aled sat looking north out toward the expanse of Nant y Moch Reservoir and a multitude of hills that radiated out in all directions. 

LIDAR summit image of Disgwylfa Fawr

Prior to visiting these hills Aled had analysed them via available LIDAR which only covers the higher of the two.  With the summit now being Trimbled the LIDAR would at least give an accurate height and position for the bwlch of Disgwylfa Fawr. 

LIDAR bwlch image of Disgwylfa Fawr

As the Trimble slowly beeped away gathering its individual datum points, I sat beside Aled whilst a slight breeze blew across the upper hill.  When data are collected gives time for my body to rest, with my mind taking over with conversation and view to enjoy.  All too soon though, the Trimble had gathered its allotted data and once switched off and photographs taken we headed down the southern slopes toward our second hill of the day; Disgwylfa Fach. 

The inward route from Llyn Syfydrin

Aled at the summit of Disgwylfa Fawr

Gathering data at the summit of Disgwylfa Fawr

Between Disgwylfa Fawr and Disgwylfa Fach is the critical bwlch for the latter, smaller heighted hill.  A fence followed the course of the bwlch in the valley to valley direction.  Either side of the fence was a mass of high reed grass, indicating bog.  We had encountered slithers of peaty wetness on the lower part of our walk down to this bwlch and even though it was high summer the ground was still wet.  In winter this would probably be a quagmire.  We debated where the critical point of the bwlch was positioned and decided it roughly followed the course of the fence and therefore I placed the Trimble on a convenient fence post, took a measurement offset between its internal antenna and the ground at its base and as Aled made his way through almost waist high reed grass to the relative comfort of the grassland beyond, I set the equipment to gather data. 

Heading toward Disgwylfa Fach

Crossing the bwlch

As the Trimble gathered its allotted data I initially lay on the reed grass below the equipment, but my shorts soon got wet and therefore I spent five minutes or so kneeling on tussocks of reed grass endeavouring to remain as dry as I could. 

My view during the bwlch survey

Gathering data at the bwlch of Disgwylfa Fach

It proved a slow plod up to the summit of Disgwylfa Fach.  At this time of year great swathes of the Pumlumon hills are covered in thick grassland, which can be torturous to walk through.  The route from bwlch to summit was not great in distance but was pathless, first through the reed grass at the bwlch followed by thick grass on the upper slopes.  It was heavy going and especially as the sun was increasing in strength and the temperature was ebbing ever upward. 

Gathering data at the summit of Disgwylfa Fach

As the Trimble gathered data from the summit of Disgwylfa Fach I again joined Aled and sat, relaxed and enjoyed the view.  Moments like this are to be savoured as all too soon the five minutes usually allocated for data collection are over and it is time to pack the equipment away and head off. 

The grasslands of the Pumlumon hills

We now had to reclaim lost height to crest the broad south-western ridge of Disgwylfa Fawr.  This was relatively easy with sheep paths followed leading us back to our inward track above the old building of Syfydrin.  By the time we arrived back at the car the temperature had rocketed.  But there were still two more walks to do, both relatively small in length, with just one for me whilst Aled planned on doing the both. 

Almost back at the car

Leaving Llyn Syfydrin I drove up the track to the narrow paved road and followed this southward toward Ponterwyd and then connected with another narrow road heading north toward Nant y Moch Reservoir, which in time led us toward our next track leading toward Banc yr Ŵyn (SN 741 902); which for me would be my last hill of a very hot day. 

 

Survey Result 

 

Disgwylfa Fawr

Summit Height:  506.1m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 73729 84737 (Trimble GeoXH 6000)

Bwlch Height:  352.5m (LIDAR)

Bwlch Grid Reference:  SN 73605 86685 (LIDAR)

Drop:  153.6m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  30.35% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

Disgwylfa Fach

Summit Height:  414.2m (converted to OSGM15)

Summit Grid Reference:  SN 73653 83882

Bwlch Height:  375.4m (converted to OSGM15)

Bwlch Grid Reference:  SN 73652 84116

Drop:  38.8m

Dominance:  9.36%

 

 

For further details please consult the Trimble Survey Spreadsheet

 

 

 

Mapping Mountains – Trimble Surveys – Banc Llechwedd Mawr

 

22.11.20  Moel y Llyn (SN 710 914), Moel y Llyn (SN 712 916), Pt. 508.8m (SN 716 914), Pt. 510.6m (SN 717 912), Banc Bwlch y Garreg (SN 729 918), Pt. 511.4m (SN 733 917), Esgair Fraith (SN 738 918) and Bryn Mawr (SN 723 906)

Moel y Llyn (SN 712 916)

This article could be entitled In Praise of Wellies.  For me, this footwear is a necessity once autumnal months set in and then progress in to winter.  Although my winter conversion from standard walking boots to the welly happened many years ago, it is only after I purchased the Trimble GeoXH 6000 that their benefits have been truly felt.  These benefits mainly consist of standing ankle deep in bog as the Trimble is gathering data at a bwlch, and today this was in evidence and as I did so, I wondered if I would even contemplate doing something similar in standard walking boots, my conclusion; probably not. 

Today I was out with Aled, we met in Machynlleth and then travelled toward Aberystwyth, turning off the main road in Tal-y-bont and following the narrow mountain road toward Nant y Moch Reservoir.  Our hills were positioned to the north with an extra hill tagged on at the end of the walk to the immediate south of the road if time and inclination permitted. 

We were walking by 8.20am across the bog just below the road and then gaining height beside an old boundary that contoured the adjacent hillside and headed west.  The conditions were ideal, with just a light breeze that brought a chilled feeling to the early morning, and with clear visibility and high cloud. 

The old boundary soon turned in to a path cutting through a rocked rib and aiming toward another good path that ascends from one of the farms in the valley below.  This now led up to the bwlch between Moel y Llyn to the west and another P30 to the east. 

The northern section of these hills were planted in conifers many years ago and as we debated where the critical point of the bwlch lay, two trail riders roared up the track that cuts a swathe up the periphery of the forest.  We stopped and chatted with them for a few minutes before they headed off on a minor track through the trees.  This left me to set the Trimble up and wait for it to gather its allotted data. 

Gathering data at the bwlch of Banc Bwlch y Garreg

Moel y Llyn is a fine hill; it consists of a number of tops, two of which have relatively large ancient cairns that have been remodelled to incorporate neat modern-day hill cairns.  One of these is the high point of the hill, the other is to its south and it was this lower summit that we now aimed for.  Once there we debated where the Trimble should be set up, as the rocks that incorporate the ancient cairn can now justifiably be thought of as a part of the hill, we therefore set the Trimble up at the base of the modern cairn and left it gathering its individual data points for six minutes. 

The higher of the Moel y Llyn summits

Between this summit and the higher is an attractive small lake and it is close to here that the bwlch for the lower hill is situated.  As we walked the short distance toward it, flashes of light illuminated the higher summit.  Sunlight on the hill at this time of year is always appealing; it accentuates the almost bleached moor and reed grass highlighting its delicate yellowed shade.  Light and shade add depth to any landscape, and this morning I stood for a few moments captivated by the scene of lake, rocky summit and late autumnal colour. 

Llyn Moel y Llyn

Looking back at the lower of the two Moel y Llyn summits that were surveyed

Once the bwlch had been Trimbled we headed up to the highest summit of Moel y Llyn, this again consists of a large ancient cairn that has now been remodelled to incorporate a modern neat cairn with the added indulgence of a near triangulation pillar on it.  Having chosen the spot for Trimble placement I set the equipment up and sat behind the cairn with Aled until the allotted five minutes of data were gathered and stored. 

Nearing the summit of Moel y Llyn

Gathering data at the summit of Moel y Llyn

Our route now headed east following the edge of the northern conifer plantation surveying each summit and bwlch as we did so.  Our next point to survey was the summit of a 511m map heighted hill.  At one time this vied for the summit of the qualifying P30, but it was usurped a number of years ago by its adjacent top.  The first summit consists of moor grass and after it had been surveyed we headed down to its connecting bwlch which consists of a large flattish bog.  Although wet in places it was nowhere near as bad as what we encountered later in the walk, and once we had assessed the lay of land a point for Trimble placement was chosen and the allotted data gathered and stored. 

Banc Bwlch y Garreg (SN 729 918)

Only a short ascent followed to the summit of the qualifying P30 and as I set the Trimble up on its high point I looked further east to the continuation of our route.  We had at least three further hills to visit and survey and the edge of the forestry would lead toward the first two of these.  I appreciated the time spent when the Trimble gathered its allotted data, as this gave me a few minutes to rest and recuperate, although all too quickly it was time to set off and head toward sheep paths through the tussock grass that gave a semblance of semi-decent underfoot conditions. 

Gathering data at the summit of Pt. 510.6m (SN 717 912)

The next point to survey was the bwlch connecting our last hill to the higher Banc Bwlch y Garreg and this was placed in a large tussock laden bog.  As I got to grips with the tussocks Aled made a detour around the bog to get on to drier land to its east.  During this he directed me to the lowest fence post that indicated where the critical point of this bwlch may lie.  I was on ground just to the north of this fence in a section of land where conifers had not been planted, or if they had, they had become water laden many years ago.  The whole place consisted of large tussocks and standing water and I spent an inordinate amount of time waiting for the Trimble to gather its data whilst standing ankle deep in water.  Walking boots would not have been appropriate and it would have been difficult to survey such a bwlch if not wearing wellies. 

Heading toward the next bwlch

Gathering data at the bwlch of Pt. 510.6m (SN 717 912)

It was a slow plod to the summit of Banc Bwlch y Garreg, as we neared its high point we each looked in to the adjacent conifers as LIDAR gives the high point of this hill approximately 19 metres in to the trees, this is a rogue summit as LIDAR is prone to give on occasion in forestry.  All land headed down from the adjacent fence in to the conifers and therefore I set the Trimble up on the summit that is easily identified and which is free of the conifer infestation and headed the short distance to where Aled was sitting and waited for the summit data to be gathered. 

Heading toward the summit of Banc Bwlch y Garreg

Gathering data at the summit of Banc Bwlch y Garreg

We were making good progress and had two summits remaining to visit, with a third as an extra to tag on at the end of the walk if wanted.  The next hill was further east and as its bwlch was to the north of the ridge fence amongst unsavoury looking land and had been LIDARed by Aled, this was bi-passed in favour of its summit.  The low point of the land between consisted of another bog but once this was delicately stepped through all that remained was the steepening slope leading up to its top.  The section of forest to the north of the ridge fence taking in the high point of this hill has recently been felled and the summit of the hill was over the fence amongst the debris of felled forestry. 

Banc Bwlch y Garreg from its adjacent easterly top

By now I was feeling tired and knew that one more hill would be sufficient for my days exploits.  Therefore, once the Trimble was set up and after it had gathered its allotted data we headed down toward a vehicle track that in time would be our way back out from the hills, but before this we headed up the same track toward the summit of Esgair Fraith, which has a map spot height of 499m. 

Heading down toward the track with the forested hill of Esgair Fraith in the background

We soon left the main forest track and veered right on to a narrower track that headed up in to a clear section of land free of forestry where the summit of Esgair Fraith is positioned.  This hill has two mounds vying for its high point, the one further north is the higher, and this is still thankfully free of trees.  The Trimble proceeded to gather ten minutes of data from the summit and I was thankful for the rest. 

Aled approaching the summit of Esgair Fraith

Gathering data at the summit of Esgair Fraith

Once the Trimble was packed away we retraced our inward route back across the lower mound and down to the main forest track which in time led us all the way back to the awaiting car. 

Heading back toward the track

On our way down the track I flagged down a farm vehicle and Aled proceeded to ask about names of near hills.  The farmer grazed land close to Llyn Dwfn and Llyn Conach; this is wild and rough land, and he confirmed many names and told us about the old estate that was sold to the Forestry Commission.  As we neared the car the adjacent hillside was aglow with the last flickers of sunlight, this only lasted a few minutes, but it was a welcome addition at the end of a day on the hill. 

Late afternoon light

However, there was one last hill to contemplate; the 489m map heighted Bryn Mawr.  I knew I wouldn’t be heading up it, but after a quick instruction on how to operate the Trimble, Aled shot up it as I remained at the car and got changed.  Thirty minutes after leaving the car he was back at it and he had also gathered data from the summit. 

It had been another good day on the hill with some beautiful late autumnal light and in all eight summits Trimbled. 

 

Survey Result: 

 

Moel y Llyn  

Summit Height:  513.0m (converted to OSGM15)

Summit Grid Reference:  SN 71075 91418

Bwlch Height:  504.6m (converted to OSGM15)

Bwlch Grid Reference:  SN 71113 91558

Drop:  8.4m

Dominance:  1.63%

 

 

Moel y Llyn  

Summit Height:  521.1m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 71264 91689 (Trimble GeoXH 6000)

Bwlch Height:  c 417m (interpolation)

Bwlch Grid Reference:  SN 75214 92896 (interpolation)

Drop:  104.1m (Trimble GeoXH 6000 summit and interpolated bwlch)

Dominance:  19.97% (Trimble GeoXH 6000 summit and interpolated bwlch)

 

 

Pt. 508.8m  

Summit Height:  508.8m (converted to OSGM15)

Summit Grid Reference:  SN 71666 91458

Bwlch Height:  498.8m (converted to OSGM15)

Bwlch Grid Reference:  SN 71738 91396

Drop:  10.0m

Dominance:  1.97%

 

 

Pt. 510.6m  

Summit Height:  510.6m (converted to OSGM15)

Summit Grid Reference:  SN 71749 91285

Bwlch Height:  476.7m (converted to OSGM15)

Bwlch Grid Reference:  SN 72327 91576

Drop:  33.9m

Dominance:  6.63%

 

 

Banc Bwlch y Garreg  

Summit Height:  520.0m (converted to OSGM15)

Summit Grid Reference:  SN 72977 91812

Bwlch Height:  466.3m (converted to OSGM15)

Bwlch Grid Reference:  SN 71556 91588

Drop:  53.7m

Dominance:  10.34%

 

 

Pt. 511.4m  

Summit Height:  511.4m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 73343 91742 (Trimble GeoXH 6000)

Bwlch Height:  490.8m (LIDAR)

Bwlch Grid Reference:  SN 73790 91963(LIDAR)

Drop:  20.6m (Trimble GeoXH 6000 summit and LIDAR bwlch) (500m Sub-Twmpau addition)

Dominance:  4.02% (Trimble GeoXH 6000 summit and LIDAR bwlch)  

 

 

Esgair Fraith  

Summit Height:  497.2m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 73893 91825 (Trimble GeoXH 6000)

Bwlch Height:  477m (spot height)

Bwlch Grid Reference:  SN 73776 91929 (spot height)

Drop:  20.2m (Trimble GeoXH 6000 summit and spot height bwlch)

Dominance:  4.06% (Trimble GeoXH 6000 summit and spot height bwlch)

 

 

Bryn Mawr  

Summit Height:  487.7m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 72354 90624 (Trimble GeoXH 6000)

Bwlch Height:  414.0m (LIDAR)

Bwlch Grid Reference:  SN 72436 90975 (LIDAR)

Drop:  73.7m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  15.11% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

For further details please consult the Trimble Survey Spreadsheet