Tuesday 21 July 2015

Mapping Mountains – Trimble Surveys – Y Berwyn


17.07.15  Grugfryn (SJ 248 356) and Y Graig Wen (SJ 240 371)  

Grugfryn (SJ 248 356)

Another evening walk had been arranged with Mark to visit two Pedwarau above Glyn Ceiriog, and with the evening’s light stretching to 9.30pm – 10.00pm we could indulge ourselves with a meal in the Oak beforehand.  I had a horrendous journey via Oswestry as part of my planned route had been closed; this meant that a 45 minute car journey lapsed into a frustrating 1 hour 40 minutes.  Thankfully Mark was still at our pre-arranged meeting place when I arrived 25 minutes late.

We parked our cars on the side of the road at SJ 245 353 and sauntered a couple of hundred metres east to a narrow lane heading left and uphill, this we followed to its top where a gate gives access into Plas-crogen Wood.  This wood consists mainly of coniferous trees with renegade deciduous saplings appearing forlornly struggling for light. 

Plas-crogen Wood is a part of the hill named Grugfryn and is listed as a Pedwar with a 403m summit spot height, I hoped to survey this summit but as the upper part of the hill is covered in conifers I wondered if I would succeed.

Once over the gate we had two tracks to choose from, one went straight up the hill and looked overgrown, whilst the other curved rightward and looked less overgrown.  First impressions can sometimes be deceptive and as we started up the right hand track this proved correct, as within a minute or so we encountered gorse and a multitude of branches overhanging the remnants of the track, which by now was no more than a path.  We pressed on with Mark using his walking poles to swipe the undergrowth and clear some form of path for us.

Entering the conifers of Plas-crogen-wood

An excellent way to spend an evening

Ten minutes of bashing later and we emerged onto the summit area which thankfully opened up giving us an opportunity to assess the land and chose a reasonable position for the Trimble to be placed.  We both judged that the probable high point was five metres from the forest track on land consisting of heather, fern and bramble.  I positioned my rucksack on the high point and placed the Trimble on top to give it elevation.  Once the level of accuracy was attained and five minutes of data gathered I measured the offset between its internal antenna and the ground as 0.49m.

Perched on top of my rucksack the Trimble gathers data at what we thought to be the summit of Grugfryn

Near to the summit was the second track which we had decided not to use at the beginning of our wee forest adventure.  However, where it emerged onto the summit area it was wide, clear and inviting; we opted to use this on our descent.  This soon proved an ill judged decision as the track succumbed to being an overgrown path within a few strides and lower down we abandoned it in favour of bashing our way through a copse of low deciduous growth.  All adventures must end and ours did likewise when we finally emerged into light and back at the gate, one hill done, one more to go.

Being submerged on our downward route

If time permitted we had an opportunity to collect data from each summit and their respective bylchau, the first bwlch was just beyond where we had parked the cars.  So backtracking from Grugfryn we walked past our cars and on our way we assessed a dried up puddle which was just on the northern side of the road, deciding its position was not at the critical bwlch we pressed on to where a broad ridge on the hill to hill traverse heads down to meet the road.  It was fairly easy to judge where the approximate position of this bwlch lay and the Trimble was placed on the grass verge beside the road having judged that a ditch the other side of the bordering hedge was man-made.  Thankfully no cars passed during the five minutes of data collection, and once complete I closed the equipment down, packed it away and joined Mark for the continuation of our evening walk.

Gathering data at the critical bwlch of Y Graig Wen

We were fortunate with the weather as it had rained most of the morning, this had cleared eastward but sunshine and showers were predicted further west for this evening, and as we walked up the lane toward Y Graig Wen a mass of bulbous grey cloud butted against the higher Berwyn with the hills further west probably immersed in summer clag.  This grey cloud accentuated the evening light as a subtle sheen of colour transposed itself onto the pastoral land we were walking through.

The light would quickly radiate the land with part illuminated colour and then disappear as the sun became obstructed behind the mass of cloud.  This effect highlighted a field of barley which swayed in the evening breeze with regimented clumps seemingly dancing in gentle motion to the beat of an imaginary rhythm.

Gentle summer rhythm

Illuminated greens and yellows

Y Graig Wen can be distinguished from afar as it now has a statue surmounted on top of a large cairn at its summit, and this is easily picked out from the surrounding countryside.  However, its south-easterly slopes are pastoral and in view of one or two farms, we wanted to avoid a direct approach and opted for a route next to a hillside of fern and sapling trees to a fence junction where we then kept to the land beside the continuing fence before striking out toward the summit.

Y Graig Wen with its large cairn and statue can be easily picked out from the surrounding countryside

By now the sun was sinking on the western horizon and the distinct shape of the high Berwyn gloomed out from the lands to our south-west.  As we headed for the summit of Y Graig Wen a herd of lively bullocks looked on, thankfully they remained a safe distance away as we neared the high point of the hill.

The high Berwyn

The small herd of bullocks

Approaching the summit of Y Graig Wen

This high point is crowned by a neat and substantial cairn that has a statue perched on top of it.  This statue is a relatively recent addition as on my previous visit in July 2003 only the substantial cairn existed.  Mark had made a passing comment that the statue resembled a garden ornament which it may do, but it does give an eloquent feel to the summit of this hill and a mysterious nature to its appearance.

Mark taking a photo from the summit of Y Graig Wen

The statue on the top of the cairn

We stayed on the summit for ten minutes taking photos and waiting for the Trimble to gather its allotted five minutes of data; once this was done we headed down toward the critical bwlch of Grugfryn which is placed in a field of long swaying grass.

Perhaps the statue was put there by the Tylwyth Teg

The Trimble gathering data at the summit of Y Graig Wen

As Mark needed to pick his wife; Louise, up in Mold at 10.30pm he needed to get back to the car, so we parted our ways near to this bwlch and I proceeded to scamper ahead through the grass to pick my spot for Trimble placement, as the grass was so long I again used my rucksack as an improvised tripod and stood back as the Trimble gathered its data.  The evening had now taken on a slight chill as the sun simpered down behind the cloud bank, I stood and waited and listened to the silence of country life in the north-eastern Berwyn as dusk crept in and the breeze blew.  A tranquil feeling if ever there was one.

Gathering data at the area of the bwlch of Grugfryn which is in the background

Once the Trimble was packed away I quickly dashed through the field to the narrow lane of our inward journey and walked speedily back to the car where Mark was preparing to leave.  It was good to catch him before he headed off and we had a few minutes chat and then went our separate ways, him to pick Louise up and me down through Selattyn toward Oswestry where I found the Welshpool road now closed which meant a 14 mile diversion to get a mile nearer home – RRRRGGGGHHHHH!



Survey Result:



Summit Height:  405.1m (LIDAR) (significant height revision)

Summit Grid Reference:  SJ 24835 35615 (LIDAR) (summit relocation)

Bwlch Height:  361.9m (LIDAR)

Bwlch Grid Reference:  SJ 24456 36336 (LIDAR)

Drop:  43.2m (LIDAR)

Dominance:  10.67% (LIDAR)






Summit Height:  406.9m (converted to OSGM15)

Summit Grid Reference:  SJ 24068 37100

Bwlch Height:  353.4m (converted to OSGM15)

Bwlch Grid Reference:  SJ 24438 35373

Drop:  53.5m

Dominance:  13.15%




For further details please consult the Trimble survey spreadsheet click {here}




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