Mapping Mountains – Summit Relocations – Yr Uchafion, 600m Twmpau and Y Pellennig – The Remotest Hills of Wales

Foel Cedig (SH 981 283)

There has been a Summit Relocation to a hill that is listed in the Yr Uchafion, the 600m Twmpau and Y Pellennig – The Remotest Hills of Wales with the summit height, its location and drop of the hill being confirmed by a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips with the bwlch surveyed on the 19^th October 2016 and the summit on the 16^th August 2018.

Foel Cedig (SH 981 283) on the left and Cyrniau Nod (SH 988 279) on the right

The criteria for the three listings that this summit relocation applies to are:

Yr Uchafion – Welsh hills at or above 500m in height that have 15m minimum drop.  The list is co-authored by Myrddyn Phillips and Aled Williams, with the Introduction to this list appearing on Mapping Mountains on the 4^th November 2015.

600m Twmpau – Welsh hills at or above 600m and below 700m in height that have 30m minimum drop, with an accompanying sub category entitled the 600m Sub-Twmpau consisting of all Welsh hills at or above 600m and below 700m in height that have 20m or more and below 30m of drop.  With the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.  The list is authored by Myrddyn Phillips.

Y Pellennig – The Remotest Hills of Wales - Welsh hills whose summit is at least 2.5km from the nearest paved public road and the hill has a minimum 15m of drop, the list is a joint compilation between Myrddyn Phillips and Aled Williams and is available as a downloadable e-booklet or print-booklet version on Mapping Mountains Publications with the up-to-date master list available on the Mapping Mountains site in Google Doc format.

The name of the hill is Foel Cedig, and it is adjoined to the Y Berwyn range of hills, which are situated in the south-eastern part of North Wales (Region A, Sub-Region A4), and is positioned to the north of Llyn Efyrnwy (Lake Vyrnwy) and has the town of Y Bala towards the north-west.

As the summit of the hill is a part of designated open access land it can be approached from various directions.  However, the easiest approach is from the north-west where a track contours the moorland and it is only a short walk from this point to the summit of the hill.

When the qualifying summit for the Yr Uchafion, 600m Twmpau and Y Pellennig – The Remotest Hills of Wales was first listed it was given to the hill named Cyrniau Nod which is positioned at SH 988 279 and listed with a 666m summit height which appears as a spot height on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map.  Whilst the summit of Foel Cedig which is positioned at SH 981 283 is given a 666m height on these same maps.

Extract from the Ordnance Survey 1:25,000 Explorer map

As the surveying technique that produced these two  spot heights has a +/- 3m margin of uncertainty applied to it, it meant that Foel Cedig could in fact be higher than Cyrniau Nod, therefore both hills were surveyed with the Trimble GeoXH 6000.

The results from these two surveys are given below:

  

Foel Cedig:  667.417m at SH 98170 28327

Cyrniau Nod:  666.207m at SH 98847 27920

Since the qualifying summit has been relocated to Foel Cedig this has also affected the lists of Marilyns, Humps, Simms, Hewitts, Nuttalls and Tumps, with Alan Dawson as list author of the Marilyns, Simms and Hewitts having accepted this result the other list authors soon followed suit.

A subsequent Leica GS15 survey conducted by John Barnard and Graham Jackson on the 15^th September 2018 resulted in the following:

Foel Cedig:  667.479m at SH 98170 28327

Cyrniau Nod:  666.234m at SH 98847 27918

Data sets of ten and eleven minutes were collected with the Trimble GeoXH 6000, whilst 122 and 121 minute data sets were collected with the Leica GS15.

The Trimble GeoXH 6000 gathering data at the summit of Foel Cedig with Cyrniau Nod in the background

The 667.4m summit height produced by the Trimble GeoXH 6000 survey and its position in relation to that of Cyrniau Nod comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies to any listed hill whose summit meets the following criteria; where there are a number of potential summit positions within close proximity and the highest point is not where previously given, or a relocation of approximately 100 metres or more in distance from either the position of a map spot height or from where the summit of the hill was previously thought to exist, or when the summit of the hill is in a different field compared to where previously given, or when the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary that is judged to be a relatively recent man-made construct.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 Explorer map is being prioritised in favour of the 1:50,000 Landranger map for detailing these relocations.

The Trimble GeoXH 6000 gathering data at the summit of Cyrniau Nod with Foel Cedig in the background on the left

The summit height produced by the Trimble GeoXH 6000 survey is 667.4m and is positioned at SH 98170 28327, this position is approximately 800 metres north-west from where the old listed summit of Cyrniau Nod is positioned.

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Y Berwyn

Name:  Foel Cedig

OS 1:50,000 map:  125

Summit Height:  667.4m (converted to OSGM15)

Summit Grid Reference (new position):  SH 98170 28327

  

Bwlch Height:  487.4m (converted to OSGM15)

Bwlch Grid Reference:  SH 94458 27324

Drop:  180.0m (converted to OSGM15)

Remoteness:  3.200 km

For details on the survey that relocated the summit of this hill

Myrddyn Phillips and Aled Williams (January 2019)