Friday 14 June 2019

Mapping Mountains – Trimble Surveys – Elenydd


10.04.19  Cripiau (SN 798 836), Banc yr Haul (SN 802 828), Pt. 518.7m (SN 802 825), Peraidd Fynydd (SN 811 824), Peraidd Fynydd (SN 809 825), Pt. 547.3m (SN 807 810), Cefn Croes (SN 808 799 [bwlch only SN 806 811]) and Pt. 555.7m (SN 803 810)  

Banc yr Haul (SN 802 828)

I’d been delaying a visit to the forested delights of Peraidd Fynydd for ten years or more, but with only a few remaining Welsh 500m P15s to visit a concerted effort was required to get my total nearer completion, so this hill needed a visit.

By the time I left Eidteddfa Gurig an east wind chilled to the bone and I started walking in what would not go amiss as full winter gear.  Usually walker’s head north from this point to the higher Pumlumon hills, but my destination today was south to open hillsides followed by forestry and ending close to the Cefn Croes wind farm before retracing my inward route back to the comforts of my car.

A steep uphill soon led to the summit of Cripiau and within a few minutes the Trimble was set atop my rucksack and data gathered.  During this process I stood with my back to the wind overlooking the descending westerly lands toward the coast.  Cloud just skimmed the higher Pumlumon tops to my north, but this was soon blown away as that east wind continued.

Gathering data at the summit of Cripiau

My next hill was due south and known locally as Banc yr Haul, I’d visited this hill twice before, each time surveying it.  The first in July 2000 with my old basic levelling staff and the second with Graham Jackson in February 2010 when we line surveyed the hill in winter conditions.

The land between Cripiau and Banc yr Haul undulates and has one or two old fences crossing it; otherwise it is bleak and wonderfully beautiful.  The connecting bwlch was soon Trimbled and I then pressed on to the conically rising summit of Banc yr Haul which is a delight to the eye compared to many of the rounded summits hereabouts.

Gathering data at the critical bwlch of Cripiau

Cripiau from the approach to Banc yr Haul

I had a number of objectives during this walk, the data from the first two hills can be compared to LIDAR analysis conducted by Aled and the second hill’s line survey, whilst there were two 500m P15s that I had not previously visited, the second of which was Peraidd Fynydd with 5m contouring on the OS Maps website showing its westerly top higher than its 547m spot heighted easterly top, I wanted to visit each and if the Trimble behaved itself gather data from their summits.  There were also two hills leading toward the Cefn Croes wind farm with one having been surveyed with my old basic levelling staff many years ago, this is a marginal P15, and both I planned on Trimbling.

Gathering data at the summit of Banc yr Haul

The connecting bwlch of Banc yr Haul was relatively sheltered and its critical point easy to identify and as the Trimble gathered its customary data I stood back out of the wind waiting patiently for the allotted five minutes of data to be stored.

Gathering data at the critical bwlch of Banc yr Haul

Pt. 518.7m (SN 802 825) from the summit area of Banc yr Haul

Ahead lay a steep slope leading to a 519m spot heighted summit which was the first of two 500m P15s I had not previously visited.  Its high point is at a junction of fences with forest butting up against the old fence on its south-western and south-eastern sides, unfortunately for surveying purposes its high point is positioned under a fallen tree and therefore having taken a ten figure grid reference from its summit I positioned the Trimble away from the trees having aligned it with the hill’s high point.  Once data were gathered and stored I headed down its slopes to enter the forest.

The Trimble marks the spot; at the summit of Pt. 518.7m (SN 802 825)

When I entered the trees my memory whizzed back to Graham and I sheltering from the snow in this spot nine years ago as the figures from our line survey were added up.  Today, conditions were more favourable, albeit that east wind still chilled.

The gap in the trees led to a wide sweeping corner on a part of the access track leading to the Cefn Croes wind farm, I was now sheltered from the wind and enjoyed being in the sun.  The connecting bwlch for the 519m map heighted hill is positioned beside the wide sweeping bend of this track and soon the Trimble was atop my rucksack gathering data.

Gathering data at the critical bwlch of Pt. 518.7m

A steady plod soon brought me to where the track continues out of the forest in a south-eastern direction which in time would lead to the high wind turbines, but I now wanted to visit Peraidd Fynydd and opted to take the north-eastward track leading down through the forest to the Nant Garw Mawr.  As I walked down the track luxuriating myself out of the wind I thought that I’d probably suffer in the afternoon sun reclaiming the height I was now loosing.

Beyond the stream the track veered south-eastward and led to felled forestry which rather conveniently has a narrow gravelled path of sorts which leads up to the forest break to the south of the easterly summit of Peraidd Fynydd.  So far everything was relatively easy, the forest break is now open on its southern side and led westward to where felled forestry ends and the conifers begin.  Entering the forest the break continued through the trees and choosing a point to leave it I used the Trimble as a hand-held device to zero in on the high point of the easterly top which consists of a greened area just free of trees and in a small break of its own.  I was hopeful for satellite coverage, and waited a long time before activating the Trimble.  Before leaving I wanted to take another data set but the equipment could not fix on to the minimum of five satellites required before logging can start.

The graveled path leading up through felled forestry toward the summit of Peraidd Fynydd

At the summit of the easterly of the two Peraidd Fynydd tops

Heading through the trees on a compass bearing I soon found myself on the continuation of the forest break that had brought me in to the trees, and opposite a gap in the trees led up the slopes of the westerly top.  Toward the top of the gap I turned right and followed a distinct ridge to its high point.  It was impossible to judge which of these two tops is higher as there is no direct line of site between them, and I had little hope of the Trimble logging on to the minimum of five satellites, let alone gathering data, but I switched it on and left it placed on top of a mound of moss under a tree and continued on the ridge to check if all ground descended from this point, it did.  Retracing my steps to the Trimble I took a few photos of it on the summit and was just about to switch it off and pack it away as it made a sound indicating that it had logged on to five satellites, considering its position I was more than surprised and soon it was beeping away gathering five minutes of data.

The route toward the summit of the westerly of the two Peraidd Fynydd tops


Gathering data at the summit of the westerly of the two Peraidd Fynydd tops

Leaving the summit I retraced my inward route back to the gap and down to the forest ride and followed this to the felled forestry and the narrow gravelled path down to the forest track where I sat on a conveniently placed bale of hay in the sunshine feeling knackered but happy.

Reclaiming height on the forest track back to where it heads toward the Cefn Croes wind farm proved a slow process as the sun warmed proceedings.  My efforts were broken when a vehicle pulled up, I chatted with the driver for five minutes or so, he worked at the wind farm and was pleasant to meet and this gave me the opportunity to recover from my uphill route.

The two tops of Peraidd Fynydd from the access / forest track

As I left the forestry following the continuation of the access track toward the wind farm the next point to survey was the bwlch of a 556m spot heighted hill and its critical point was beside the track.  Once data were gathered and stored I continued on the track as it calved its way through the next hill I wanted to survey with its connecting bwlch to the east of its summit and in a bog.

Gathering data at the critical bwlch of Pt. 555.7m


The Cefn Croes wind farm

I took two data sets on the valley to valley traverse in the bog and stumbled toward the Trimble through small tussocks of bog grass as I checked on its progress, once the allotted data were stored I switched it off and headed in the bog to the next point to survey.  During this I stood back and immersed myself in the scene, these hills are wild affairs, although the wind farm has taken part of this wild quality away, however they are still pleasing.

Gathering data at one of two positions surveyed for the critical bwlch of Pt. 547.3m

As I slowly plodded out of the bog and back through a gate on to the access track and up initial steep slopes to the next summit I felt wiped out and knew that the outward route would have to be taken slowly.  I took data sets from two positions on the summit area of this small hill, one on an attractive grassed area and the other amongst tussocks, with the former my candidate for its high point.

Gathering data at the summit of Pt. 547.3m (SN 807 810)

I only had one survey remaining that I wanted to complete but between me and it lay another bwlch, at the time I didn’t know that this is the critical bwlch connecting to Cefn Croes, but as I was passing I thought I’d better gather data from it.  As the Trimble did its stuff I sat on grass beside a fence under the access track not wanting to move, just wanting to sit and recover.

Gathring data at the critical bwlch of Cefn Croes
Just one summit remained; the 556m spot heighted hill whose connecting bwlch is placed beside the access track and which I had surveyed as I emerged out of the confines of the forest.  Its high point consists of wind- blown grass and as the Trimble gathered its data I sat below it to its west and looked out on the wild surrounds of Llynnoedd Ieuan.

The last survey of the day; at the summit of Pt. 555.7m (SN 803 810)


The last hill of the day; Pt. 555.7m (SN 803 810)

All that remained was the long walk out.  I’d asked the person who had pulled up in his vehicle what time the remaining workers at the wind farm would be heading down the access track to the A44, he told me at about 4.00pm.  Leaving the last summit I walked down its grassed northerly ridge and made it back on to the track at 4.05pm, ate a banana and continued north slowly on the track stopping occasionally in the faint hope of hearing a vehicle approaching.  Suddenly the hum of a red van rounding a corner ignited forlorn hope and I stood, smiled, and pleaded with a thumb in the air for it to stop, the driver smiled and waved and ever so slowly passed, he went so slowly that I thought he was stopping, he wasn’t, and I watched him disappear in a red dot around the next corner.

By now I thought I’d struggle over Banc yr Haul and Cripiau on my way back to Eisteddfa Gurig, so decided to wait at the wide sweeping corner where the gap through the trees gives access toward these two hills, hoping for more vehicles to approach.  Soon one appeared and stopped, the driver offered to drop me at the road but couldn’t take me up to Eisteddfa Gurig as he was already late to pick his daughter up, however he said that a delivery lorry was on its way down the track and the driver was heading toward Welshpool.  I’d waved at this same delivery lorry as it headed toward the wind farm earlier in the afternoon, it soon appeared and the driver took pity on me and within a few minutes I was sitting in the cab.

The driver; Keiron Maddocks enjoyed hill walking so we happily chatted about the hills I had just visited and his various trips to the Lakes and Scotland.  I felt relieved to have got a lift and thanked Keiron a number of times as he drove down the remainder of the track toward the A44.

Keiron saved me a long walk out

I waved him off as he dropped me beside my awaiting car, and duly paid the £5.00 parking fee putting the money through the red doored letter box as instructed.  All that remained was a visit to Eryl and Rita’s in Llanidloes for a couple of hours catch up and a very welcome mug of tea and a lovely meal.       

        

Survey Result:



Cripiau 
 
Summit Height:  510.5m (converted to OSGM15)

Summit Grid Reference:  SN 79838 83644

Bwlch Height:  485.1m (converted to OSGM15)

Bwlch Grid Reference:  SN 79927 83280

Drop:  25.4m

Dominance:  4.98%






Summit Height:  525.6m (converted to OSGM15)

Summit Grid Reference:  SN 80202 82864

Bwlch Height:  495.0m (converted to OSGM15)

Bwlch Grid Reference:  SN 80293 82632

Drop:  30.6m (Trimble GeoXH 6000)  30.6m (Level and Staff line survey)

Dominance:  5.83%





Pt. 518.7m

Summit Height:  518.7m (converted to OSGM15)

Summit Grid Reference:  SN 80249 82542

Bwlch Height:  500.5m (converted to OSGM15)

Bwlch Grid Reference:  SN 80329 82559

Drop:  18.2m (Uchaf status confirmed)

Dominance:  3.51%





Peraidd Fynydd

Summit Height:  547m (spot height prioritised)

Summit Grid Reference:  SN 81166 82428

Bwlch Height:  c 526m (I)

Bwlch Grid Reference:  SN 80853 82417 (I)

Drop:  c 21m 

Dominance:  3.84%





Peraidd Fynydd 
 
Summit Height:  546.7m (converted to OSGM15)

Summit Grid Reference:  SN 80994 82517

Bwlch Height:  c 533m (I)

Bwlch Grid Reference:  SN 81044 82468 (I)

Drop:  13.7m

Dominance:  2.51%





Pt. 547.3m
  
Summit Height:  547.3m (converted to OSGM15)

Summit Grid Reference:  SN 80706 81044

Bwlch Height:  530.9m (converted to OSGM15)

Bwlch Grid Reference:  SN 80823 81083

Drop:  16.4m (Uchaf status confirmed)

Dominance:  3.00%





Cefn Croes  

Summit Height:  573m (Lev)

Summit Grid Reference:  SN 80800 79953 (HH)

Bwlch Height:  529.5m (converted to OSGM15)

Bwlch Grid Reference:  SN 80617 81118

Drop:  43m

Dominance:  7.59%





Pt. 555.7m

Summit Height:  555.7m (converted to OSGM15)

Summit Grid Reference:  SN 80394 81092

Bwlch Height:  531.5m (converted to OSGM15)

Bwlch Grid Reference:  SN 80417 81360

Drop:  24.1m

Dominance:  4.34%








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