Mapping Mountains – Trimble Surveys – Moelwyn Mawr

06.10.18  Coed Eryr (SH 636 508)  

I’ve visited Eryri many times over the years, mainly concentrating on its higher peaks, but also taking in a number of its lower hills, but more remain to visit and having the Trimble as an effective and accurate lightweight accessory on any hill walk only encourages me to continue visiting these hills.

A hill that until today I had not visited is Coed Eryr, which is situated between the waters of Llyn Dinas and Llyn Gwynant and rises in a conifered bulk above Nant Gwynant.  Reports on the Hill Bagging website advised an approach on an unmarked track leaving the confines of the valley from the convenience of a large lay-by adjacent to a row of houses.  However, reports also stated that the last 50 metres or so to the summit were problematic.

As I left my car and started up the track the first colours of autumn were on show as dulled browns of bracken intermingled with moss strewn trees.  The track made good steady progress uphill as all good tracks should! 

The track was mainly enclosed by conifers but the view did open to show one whitened house against a backdrop of Llyn Gwynant and the rising and steep grassed slopes of Gallt y Wenallt.  As the track crested the hill’s northerly ridge it veered south toward the land containing the summit.

Gallt y Wenallt and Llyn Gwynant

In places the track was muddy with an occasional fallen tree hanging over it, thankfully any quagmire could easily be bi-passed and the fallen trees could be walked under.  I left the track just beyond its high point and started the difficult bit, which at its beginning proved relatively easy, but fun soon arrived as the debris of rhododendron clearing had left a jungle of wooded branches beyond which, somewhere through the mass of entanglement was the summit.

Somewhere up there is the summit

Somewhere through there is the summit

Thankfully the difficulties were short lived and after a good branch bash I arrived beside a tree that had an aerial fixed to it, within a metre or so this position matched that produced by LIDAR analysis and once I had visually determined the high point I placed the Trimble at the summit, took a photograph and then positioned it on top of my rucksack for data collection.

The aerial on the tree marks the summit area

The Trimble marks the summit

I waited an inordinate amount of time for the equipment to ebb down to its 0.1m accuracy level before data should be logged, and then proceeded to gather ten minutes of data, during this wait I spent a few minutes breaking small branches off clearing a path toward the summit.

Gathering data at the summit of Coed Eryr

Once data were stored I retraced my inward route back to the track, which on the descent seemed easier when compared to the uphill bash, stopping to admire Llyn Gwynant on the way and talk with a couple who were heading up the track toward the Bryn Gwynant Youth Hostel.

It had been a good small circuit with another hill visited, next stop were two hills that I’d often thought about visiting but again, never had; Foel Gron (SH 583 621) and Pen y Bigil (SH 576 621).

Survey Result:

Coed Eryr

Summit Height:  243.7m (converted to OSGM15, Trimble GeoXH 6000) (significant height revision)

Summit Grid Reference:  SH 63612 50890 (Trimble GeoXH 6000)

Bwlch Height:  181.6m (LIDAR)

Bwlch Grid Reference:  SH 64230 51021 (LIDAR)

Drop:  62.1m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  25.49% (Trimble GeoXH 6000 summit and LIDAR bwlch)

For further details please consult the Trimble Survey Spreadsheet