Mapping Mountains – Trimble Surveys – Yr Eifl

 

17.09.22  Mynydd Mawr (SH 140 258) 

Mynydd Mawr (SH 140 258) from a previous visit to the hill

As a child my family holidayed at Morfa Nefyn and Edern.  I have a distant memory that during one of these holidays we headed to the end of Pen Llŷn and drove up the concrete road that leads to the summit of Mynydd Mawr.  We could have done this more than once, but my memory only retains small segments from my childhood and even these only give me the semblance of one distant childhood visit. 

For many years we spent our holidays in this house in Morfa Nefyn

It would be many years later when I next visited this hill and since then I have been back to survey its summit and visited again with my brother.  This time I was with my aunt, cousin and brother.  We were staying in Nantlle and a road trip taking in the beauty of the Llŷn had been suggested. 

The view from the coast at Nefyn

It is all too easy to accept the land one lives in; after all it is the land one is used to.  However, heading from Welshpool to Nantlle my aunt and cousin both marvelled at the beauty of the land we were travelling through.  I had done this journey countless times over many years and although I would like to think my eye is still appreciative of this land, there is no doubt an acceptance on my part, as for me it is a constant.  Seeing it with new eyes through the experience of my aunt and cousin gave me added appreciation of just how beautiful this land is and by that fact, how fortunate I am to live where I do.

On our way down Pen Llŷn we visited the old houses where we holidayed, reminiscing on times now long gone.  A multitude of narrowing lanes lead west down the Llŷn toward the paved road that starts its way up Mynydd Mawr, this soon turns in to a concrete road ending at the top of the hill, where a levelled section gives adequate parking for a number of cars.  We weren’t the only ones heading up this hill, there were a few walkers on the manicured green paths, but in the main it was the convenience of a car that brought people here. 

Looking inland toward the high Eryri peaks

Having parked I sauntered off to stand on the high point and before joining Bryn, Shirley and Julie I took a few minutes to look inland toward the higher peaks of Eryri which were framed by a sweeping coastline.  It was a stunning view, whilst behind the great swathe of the Irish Sea dominated, following this around and the bulk of Ynys Enlli looked back as a darkened silhouette, whilst to its right a slight greyed outline of the distant Wicklow hills, south of Dublin could just be picked out.

Leaving the summit I joined Bryn, Shirl and Julie on the series of steps leading down with the distant Ynys Enlli ahead.  We followed these for a while before stopping, all round was the expanse of sea, a huge blue mass stretching to the horizon. 

Looking out toward Ynys Enlli

We stayed looking out to sea for quite some time and once heading back up the steps we veered rightward to join one of the paths leading up the hill toward the top, this soon led us back to the car.  It’s always good to visit this summit, be it by foot or car.  It signifies an end of land and if the weather conditions are favourable, as they were today, it can give a dramatic element to this beautiful land that we live in. 

 

Survey Result:

 

Mynydd Mawr

Summit Height:  160.0m (converted to OSGM15, from previous Trimble GeoXH 6000 survey)

Summit Grid Reference:  SH 14021 25869 (from previous Trimble GeoXH 6000 survey)

Bwlch Height:  64m (spot height)

Bwlch Grid Reference:  SH 14952 26292 (spot height)

Drop:  96m (Trimble GeoXH 6000 summit and spot height bwlch)

Dominance:  60.00% (Trimble GeoXH 6000 summit and spot height bwlch)

 

 

For details on the survey of Mynydd Mawr

For details on the 2^nd visit to Mynydd Mawr

 

For further details please consult the Trimble Survey Spreadsheet

 

 

 

Mapping Mountains – Trimble Surveys – Yr Eifl

11.04.21  Mynydd Mawr (SH 140 258) 

Mynydd Mawr (SH 140 258) from my previous visit to the hill

The last time I visited Mynydd Mawr was in the early life of my Trimble when accompanied by Aled and Mark we visited the hill and I surveyed its summit.  On that day we chased daylight hours as this was in Decemeber 2014 and after descending the hill we walked up the adjacent Mynydd y Gwyddel.  Here we stayed watching as the last embers of daylight sank behind the blackened profile of Ynys Enlli giving a beautiful sun set. 

Watching the sun set after my previous visit to Mynydd Mawr

Today was at contrast as I was out with my brother; Bryn, touring the Llŷn and investigating its minor roads.  We had no definite destination, just to get out whilst enjoying the company that Covid had starved us of over the last year or so. 

Although we had no definite destination I had mentioned driving up Mynydd Mawr, but again we just aimed west and carried on.  By doing this we found ourselves at the base of the hill, and once here we were definitely going to aim for its summit. 

The weather conditions were also at contrast to my last visit, this as described above gave late afternoon winter light before we stood and quietly watched the sun set.  Today showers were forecast with a mixture of sleet and snow.  Before setting off we had watched large flakes of snow fall for an hour or so, cloaking near hills.  By the time I drove up the concrete access road leading to the top of Mynydd Mawr the snow had quickly thawed from this part of the world and glimmers of sun and little breeze warmed us as we got out of the car. 

The end of the concrete road

Bryn headed off toward a rocky knoll to look out to sea, whilst I scampered up to the high point of the hill.  Away to our west and out to sea huge shower clouds were massing.  Beyond Ynys Enlli, which today was greyed with slithers of spring green on its slopes, whitened winter showers were also breaking out across the sea.  But the one that dominated was blackened grey with a whitened cap; this took up much of our immediate attention.  It massed out to sea forever heading eastward directly toward the end point of the Llŷn. 

Gathering data at the summit of Mynydd Mawr during my previous visit

Same place, but different weather conditions

My brother called over as I headed his way from the summit, he just stood and pointed out to sea toward the increasingly large darkened mass of wintery shower cloud.  We knew it was heading directly toward us as by the time I had sauntered a little lower to look back up and take a few photographs, and then having re-joined Bryn, the wind had picked up and the last vestiges of sunlight were now overtaken by the darkened mass. 

Darkened shower clouds mass

We looked out to sea one last time and headed toward the car.  Driving down the concrete access road the first large drops of rain hit the windscreen.  By the time we were back on the narrow roads it was sleeting and the onward journey involved watching as huge showers took over the sky.  These were accentuated as small parts of the land were still bathed in sunshine, whilst seemingly all other land was greyed and covered in wet murk. 

It was a dramatic journey back to Nantlle watching the ever changing sky as large shower clouds obliterated the landscape.  However, it had been a good road trip and especially as we’d made the summit of Mynydd Mawr before the sleet had set in. 

 

Survey Result: 

 

Mynydd Mawr

Summit Height:  160.0m (converted to OSGM15, from previous Trimble GeoXH 6000 survey)

Summit Grid Reference:  SH 14021 25869 (from previous Trimble GeoXH 6000 survey)

Bwlch Height:  64m (spot height)

Bwlch Grid Reference:  SH 14952 26292 (spot height)

Drop:  96m (Trimble GeoXH 6000 summit and spot height bwlch)

Dominance:  60.00% (Trimble GeoXH 6000 summit and spot height bwlch)

 

 

For details on the survey of Mynydd Mawr

For details on the 3^rd visit to Mynydd Mawr

 

For further details please consult the Trimble Survey Spreadsheet

 

  

Mapping Mountains – Trimble Surveys – Yr Eifl

03.10.18  Cae Doctor (SH 304 399)  

The summit of Cae Doctor (SH 304 399)

This hill was the last of seven visited during the day with each summit being Trimbled, and as a marginal P30 and its bwlch not LIDARed, the summit and bwlch needed Trimbling. 

The summit of this hill comprises two glazing fields that are separated by an old and high field boundary incorporating a stone wall, gorse hedge and fence.  If time permitted I wanted to take a data set from each side of this boundary, but as the high ground of each field was visually similar, one data set was deemed sufficient if also bwlch data were gathered.

Leaving the car we followed a track that soon brought us to the boundary hedge, and deciding to survey the eastern side Aled walked the periphery of the field boundary and stopped where he judged the natural summit of the hill to be situated, within a couple of metres this matched the grid coordinates produced by LIDAR.

I placed the Trimble on top of a fence post to give it elevation above its immediate surrounds and with the assistance of Aled measured the offset between its internal antenna and the ground below and once the 0.1m accuracy level was attained pressed ‘Log’ and we each then stood either side of the equipment and a few metres away from it.

Gathering data at the summit of Cae Doctor

During data collection two vehicles appeared on the hillside opposite, the higher one belonged to the local gamekeeper, whilst the lower vehicle was dropping feed off for livestock and turned out to be the local farmer, we found this out after the Trimble had gathered its allotted data and was packed away, as when we walked toward the gate giving access to our inward track we were met by the local farmer, who seeing us in the field had driven up the track to find out what two people were doing standing in her field for ten minutes or so about 50 metres apart.  It was time for an explanation.

The Trimble set-up position at the summit of Cae Doctor

The local farmer is Awen Roberts and she proved more than helpful as once the Trimble and its function and our interest in upland place-name research was explained she told us that the field where we had been standing is known as Cae Doctor, and the adjacent field on the other side of the boundary hedge is known as Cae Myllt, and she then gave permission for the other high field to be surveyed.

Having thanked Awen we walked in to the other high field, found its natural high point and again I positioned the Trimble on an adjacent fence post and waited for the allotted data to be gathered and stored.  All that remained was to visit and gather a data set from the bwlch.

Gathering data at the summit of Cae Myllt

The bwlch for this hill lies in a long valley that is steep sided with a public footpath leading us to where contour interpolation places its critical point.  Again the Trimble was placed on top of a fence post to give it elevation and the offset measured, and once the allotted data were gathered we walked back up to the awaiting car and I then drove the short distance to Nefyn. 

Heading toward the bwlch

The first data set in the area of the bwlch

The reason for doing so is that the Ordnance Survey Interactive Coverage Map hosted on the Geograph website gives a 37m spot height at a road junction that could be the position of this hill’s critical bwlch, although we had dismissed this from our on-site visit to the valley as ground beyond where the Trimble had gathered data seemed to descend toward this road junction.  However, being a completest I wanted this last data set as a comparison with the previous one.

The second data set in the area of the bwlch

Once this last data set was stored I joined Aled in the car and drove back to pick his car up.  Once home Aled analysed LIDAR and determined the height and position of this hill’s bwlch, and when coupled with the Trimble summit data the hill retains its P30 status and increases its known drop value, and these values are given below.

  

Survey Result:

Cae Doctor (significant name change)

Summit Height:  67.0m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 30425 39978 (Trimble GeoXH 6000)

Bwlch Height:  35.8m (LIDAR)

Bwlch Grid Reference:  SH 30747 40107 (LIDAR)

Drop:  31.2m (Trimble GeoXH 6000 summit and LIDAR bwlch) (30-99m Sub-Twmpau reclassified to 30-99m Twmpau)

Dominance:  46.59% (Trimble GeoXH 6000 summit and LIDAR bwlch)

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Trimble Surveys – Yr Eifl

03.10.18  Moel y Penmaen (SH 338 386)  

As I drove north from Yr Orsedd (SH 299 270) toward Moel y Penmaen the morning’s sunshine had been replaced with a flat greying sky which had pushed eastward blanketing the higher hills. 

Approaching Moel y Penmaen Aled directed us to the track leading to Penmaen Uchaf; the farm at the south-eastern base of what was going to be our sixth hill of the day.  We decided to drive up the track and ask if we could park and visit the hill from the convenience of the farm, thankfully the framer said yes.

A green track led from the farmyard through a gate around the eastern side of the upper part of Moel y Penmaen.  To our north-east the nipple like summit of Mynydd Carnguwch stood out, monochromed against the grey sky with a lightened glimmer of sunlight piecing the greened fields in the foreground.

Heading for the summit

Mynydd Carnguwch

Leaving the green track it was only a short distance to the summit which consists of attractive patches of rock, with two vying for the high point of the hill.  I soon had the Trimble set up on what we both thought to be the highest, improvising by balancing the rear of the equipment on my glasses case to keep it horizontal.

Gathering data at the summit of Moel y Penmaen

All that remained was a second data set, this time taken from the small patch of rock that we considered lower, and as we had another hill to visit and time was pressing a two minute data set was taken, which according to Trimble is the minimum advised for an accurate result.

Gathering data at the second Trimble set-up position on Moel y Penmaen

Once the Trimble was packed away we followed our inward route down the hill and thanked the farmer for giving us permission to park and visit the hill from his farm and then headed off toward our last hill of the day; Cae Doctor (SH 304 399).

Survey Result:

Moel y Penmaen

Summit Height:  153.1m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 33804 38683 (Trimble GeoXH 6000)

Bwlch Height:  92.8m (LIDAR)

Bwlch Grid Reference:  SH 34629 39659 (LIDAR)

Drop:  60.3m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  39.39% (Trimble GeoXH 6000 summit and LIDAR bwlch)

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Trimble Surveys – Yr Eifl

03.10.18  Yr Orsedd (SH 299 270)  

Yr Orsedd (SH 299 270)

Part of the fun of visiting a small heighted hill is the adventure of getting to its summit; this can involve all manner of clandestine manoeuvres and even when within reach of its all-important high point a profusion of undergrowth can add complication to the matter at hand.  Visiting these small heighted hills also gives opportunity to make local place-name enquiries as many of these hills do not possess a map name.

Having visited three near hills and gone on a bag of chips hunt for a lunch time snack Aled and I headed the short distance from Abersoch south-westward toward the small community of Llanengan, where two fields about 500 metres apart vie for the accolade of claiming P30 status.  The prestige of being classified as the P30 used to belong to the 64m map heighted south-westerly hill which is known locally as Bryn Tŷ Newydd, however eagle eyed map studiers spotted that the Ordnance Survey Interactive Coverage Map hosted on the Geograph website gives a 66m spot height to the north-easterly hill which is known locally as Yr Orsedd.

As LIDAR confirms Yr Orsedd as higher than Bryn Tŷ Newydd we only had the former on our radar to visit and Trimble today.  I parked my car to the east of the summit, toward the end of a road junction giving sufficient space for other cars to pass and away we went heading toward a gate which gave access to a manicured field leading toward the summit of the hill.

Aled heading toward the summit

Even from this approach the gorse on the upper part of the hill was on show and as we arrived at the boundary fence adjacent to the summit it looked positively evil.  Aled headed in to it first and easily found the high point, he stood on the summit amongst the gorse, chest high in the stuff, and this didn’t give me much hope for Trimble satellite reception.  I soon joined Aled and positioned the Trimble atop my rucksack giving it a semblance of elevation above its immediate surrounds, and stood back as it ebbed down to its 0.1m accuracy level before data should be logged.  This was attained remarkably quickly considering its position, and once gathering data I left it in situ for ten minutes.

Aled at the summit of Yr Orsedd

Gathering data at the summit of Yr Orsedd

As the Trimble gathered its allotted data I looked out toward Garn Fadrun, its scree laden slopes edged in a hint of afternoon sunshine.  To the south-west Bryn Tŷ Newydd shone back manicured green with a foreground of grazing cattle and Mynydd Cilan as backdrop.  Below us a quad bike buzzed around in the adjacent field, and we wondered if this was the local farmer, and if so he would probably be able to help with the name of the hill, but as I switched the Trimble off and packed it away he had driven off.

The Trimble set-up position at the summit of Yr Orsedd

The scree laden slopes of Garn Fadrun

The manicured grazing fields of Bryn Tŷ Newydd

We descended north from the summit and called at a house hoping to ask about the hill and its name, no one was in.  Undeterred I headed up the road toward the next house and Kate met us on her drive, once introductions and explanations had been given she explained that her partner; Wyn, was the farmer who we had seen on his quad bike and that he had headed down to Porth Neigwl (Hell’s Mouth) to feed the cattle.  Thanking Kate we went in search of Wyn.

I flagged Wyn down as he drove back up the road from Porth Neigwl and he told us the names for both hills; Yr Orsedd and Bryn Tŷ Newydd, the details of which will appear in a Significant Name Changes post, and after thanking Wyn for his time we headed north toward our next hill; Moel y Penmaen (SH 338 386).

Survey Result:

Yr Orsedd (significant name change)

Summit Height:  67.5m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 29952 27038 (Trimble GeoXH 6000) (summit relocation confirmed)

Bwlch Height:  32.0m (LIDAR)

Bwlch Grid Reference:  SH 29808 27337 (LIDAR)

Drop:  35.4m (Trimble GeoXH 6000 summit and LIDAR bwlch) (30-99m Sub-Twmpau reclassified to 30-99m Twmpau)

Dominance:  52.52% (Trimble GeoXH 6000 summit and LIDAR bwlch)

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Trimble Surveys – Yr Eifl

03.10.18  Clip y Gylfinhir (SH 223 284)  

Clip y Gylfinhir (SH 223 284)

Clip y Gylfinhir was previously surveyed with the Trimble GeoXH 6000 on the 28^th December 2014, the resulting height proved substantially lower than the 270m spot height that appears on the Ordnance Survey 1:25,000 Explorer map, and as the Standard Deviation and Estimated Accuracies indicated the data set was not good, I wanted to re-visit and survey this hill’s summit ever since.  The opportunity to do so was now here as Aled and I had visited Mynydd Penarfynydd and Mynydd y Graig and it was only a short drive from these hills to the parking area at the base of Clip y Gylfinhir, and whilst surveying this hill Aled could visit the adjacent Mynydd y Rhiw, a hill he had not previously been up.

Clip y Gylfinhir thrusts upward and is coned in profile, it stands out even from afar as a pimple like addition to the southern slopes of its higher neighbour; Mynydd y Rhiw, and the hill has association with the Tylwyth Teg; the mythological fairy like creatures of Welsh folklore.

As Aled headed north toward the trig pillar atop Mynydd y Rhiw I left a friendly Shetland pony beside my car and as it nuzzled its head against the boot, and hoped that it would not attempt to eat my rear wiper blade whilst I was on the hill!

Aled on the summit of Mynydd y Rhiw

A paved road leads to the adjacent mast and radar station that now sits beside Clip y Gylfinhir, from this paved road the hill thrusts upward, with it being steep on all sides.  I followed the road to its end and slowly plodded up the steep rocky slopes toward its summit where an autumnal breeze met me as it blew in from the sea.

The previous time this hill was Trimbled I’d placed the equipment aligned with the highest rock, this time I wanted the Trimble to be elevated above its immediate surrounds and therefore placed it on top of my rucksack which acted as an improvised tripod, having measured the offset between its internal antenna and the ground below I pressed ‘Log’ and waited for ten minutes of data to be gathered and stored.

Gathering data at the summit of Clip y Gylfinhir

The Trimble set-up position at the summit of Clip y Gylfinhir

As the Trimble gathered data I sat below it watching Aled making good progress up the path to the summit of Mynydd y Rhiw, he was descending the hill as the Trimble continued beeping away gathering its 600 individual datum points, once data were stored I closed the equipment down, packed it away and headed down to the paved road and arrived back at the car no more than a minute or so before Aled did likewise.

Survey Result:

Clip y Gylfinhir

Summit Height:  267.8m (converted to OSGM15) (significant height revision)

Summit Grid Reference:  SH 22395 28472

Bwlch Height:  240.1m (converted to OSGM15) (from previous Trimble GeoXH 6000 survey)

Bwlch Grid Reference:  SH 22514 28524 (from previous Trimble GeoXH 6000 survey)

Drop:  27.7m

Dominance:  10.34%

For details on the first Trimble survey of Clip y Gylfinhir

For further details please consult the Trimble Survey Spreadsheet