Saturday 5 January 2019

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:




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)










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