Mapping Mountains – Trimble Surveys – Yr Eifl

03.10.18  Mynydd Ystum (SH 187 284)  

Mynydd Ystum (SH 187 284)

The Llŷn is always a joy to visit, and especially its western part where sea meets land and the ebb of time seems to be stilled.  Today I was out with Aled on a mini bagging bonanza with a number of hills on our radar, all of which were planned to be Trimbled, however these plans were not too strict and we decided that we would just see how things progressed during the day.

Our first hill was Mynydd Ystum, which is positioned in the central part of land as it narrows toward the tip of the Llŷn overlooking the B 4413 road, which this morning was relatively quiet with only a few vehicles passing to and fro.  I parked beside this road on the grass verge and once all necessary gear was sorted we headed through a gate to an open field and a short walk toward the gorse laden upper slopes of the hill.

Mynydd Ystum is crowned by the remains of an ancient hill fort named Castell Odo, which comprises two concentric ramparts, which are now reduced in height.  Centred on the summit is a triangulation pillar with the high point of the hill about one metre from its base.

To our south-west the morning’s sun highlighted the rock strewn bulk of Ynys Enlli as it rose skyward, seemingly attached to the mainland from this viewpoint.  Stretching north-eastward the coast continued out of sight with the sea enveloping the land to the north, west and south.  It was a pleasure being on this hill and taking in this scene as the play of sun and cloud cast light and shadow across the land.

The rock carved bulk of Ynys Enlli

As the Trimble gathered its allotted data this scene slowly stood with its patch-worked fields, stone walls and hedges, hill top and valley bottom and a never ending coast and sea.  I found it mesmerizing.

Gathering data at the summit of Mynydd Ystum

Once the allotted data were gathered and stored I packed the Trimble away and we made our way back through the upper gorse to the open field below, as a number of cows frisked our way, inquisitively running, then halting as they neared us, before they ran off again.

The small herd of inquisitive and frisky cows

Survey Result:

Mynydd Ystum

Summit Height:  146.2m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 18705 28466 (Trimble GeoXH 6000)

Bwlch Height:  81.6m (LIDAR)

Bwlch Grid Reference:  SH 19608 29535 (LIDAR)

Drop:  64.6m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  44.17% (Trimble GeoXH 6000 summit and LIDAR bwlch)

For further details please consult the Trimble Survey Spreadsheet