Mapping Mountains – Trimble Surveys – Yr Eifl

03.10.18  Mynydd Penarfynydd (SH 220 265) and Mynydd y Graig (SH 227 274)  

Mynydd y Graig (SH 227 274)

The south-western Llŷn portrays a land that is apart, an end.  This is more so than a land that meets sea; as it portrays a differing life, one seldom encountered further inland.  This aspect is enhanced by narrow lanes, few signposts, dotted farms joined by earthen tracks, and tranquillity all of its own.  There are few other places in Wales that can compare.

Although I’d been on this part of the Llŷn many times before, it still held hills that I had not visited and today Aled and I wanted to investigate ones that we had both neglected until now.  Having visited Mynydd Ystum (SH 187 284) we headed east and parked on a narrow lane at the base of Mynydd y Graig, whose summit rose in castellated rock outcrops above.

To our south-west the Llŷn stretched seaward where Maen Gwenonwy, Ynys Gwylan Fawr, Ynys Gwylan Fach and Ynys Enlli were bathed in morning sunshine, all looking resplendent with only Maen Gwenonwy attached to the mainland by a slither of tidal debris.

Like bejeweled rocks cast in to the sea; (L-R) Ynys Gwylan Fach, Ynys Gwylan Fawr, Ynys Enlli and Maen Gwenonwy

The narrow track we were on led toward the connecting bwlch between Mynydd Penarfynydd and Mynydd y Graig, as it had been LIDARed we bi-passed it and joined the footpath leading to the summit of Mynydd Penarfynydd.

Mynydd Penarfynydd (SH 220 265)

The path led up at a gentle gradient to the triangulation pillar on the summit and a few minutes later the Trimble was set up and gathering data at the high point of the hill, during this Aled headed further down the ridge to sit and admire the view, I soon followed.

Gathering data at the summit of Mynydd Penarfynydd

Mynydd Penarfynydd is a part of a butting promontory where land meets the sea and although only relatively small in height it none the less gives a marvellous sense of height as it clings on above the sea, and today when bathed in early October sun it was a wonderful place to be.

Once the Trimble had gathered and stored its allotted data we retraced our route back down toward the connecting bwlch as greying cloud massed inland over the higher peaks of Eryri.

Ahead lay Mynydd y Graig, a fine and apt name for the hill.  We followed the main path around the hills eastern slopes instead of its narrow ridge path from the bwlch, this meant a steep ascent toward the ridge but gave endless seascapes on the way.

The summit of Mynydd y Graig is crowned by a number of large rocks, with two vying for the accolade of highest point, both were Trimbled.  Aled arrived at the summit first, I soon joined him and then delicately positioned the Trimble on the high point of the first large rock, aligning its internal antenna to its highest point and for ease of placement this meant the equipment was pointing west, resulting in it logging on to only one or two satellites, therefore I repositioned it pointing north-eastward with the end of the equipment only a centimetre or so from Trimble oblivion.  Before activating the Trimble to gather data I wedged it in place with three small rocks, then pressed ‘Log’ and hoped it would still be in situ once the allotted data were gathered and stored.

Aled at the summit of Mynydd y Graig

During this first summit survey Aled visited the second large rock and looked back toward the first where the Trimble was positioned, he thought both close in height and therefore the second large boulder definitely needed Trimbling.

The second boulder proved a little easier to position the Trimble on top of, and again I used the same three small rocks to wedge it in place during data collection.  As Aled waited near the first large boulder I sat and savoured the view, and thought that these two hills when combined give a marvellous small walk.

Gathering data at the second large boulder with Aled standing at the top of the first large boulder and what proved to be the summit of Mynydd y Graig

Once the Trimble was packed away I re-joined Aled and we headed down following a narrowing footpath back to the small lane where the car had been left, next stop was a short distance to our north with a visit to Clip y Gylfinhir for me and Mynydd y Rhiw for Aled.

Survey Result:

Mynydd Penarfynydd

Summit Height:  177.4m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 22008 26580 (Trimble GeoXH 6000

Bwlch Height:  142.0m (LIDAR)

Bwlch Grid Reference:  SH 22322 26725 (LIDAR)

Drop:  35.4m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  19.93% (Trimble GeoXH 6000 summit and LIDAR bwlch)

Mynydd y Graig

Summit Height:  242.5m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 22785 27433 (Trimble GeoXH 6000)

Bwlch Height:  186.0m (LIDAR)

Bwlch Grid Reference:  SH 22762 27947 (LIDAR)

Drop:  56.5m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  23.31% (Trimble GeoXH 6000 summit and LIDAR bwlch)

For further details please consult the Trimble Survey Spreadsheet