Foel Penolau – P30 Hewitt and Simm status confirmed

The P30 status of Foel Penolau has been confirmed for the following lists; Simms, Hewitts and Twmpau with Alan Dawson as list author for the first two and Myrddyn Phillips list author of the Twmpau. 

Foel Penolau (SH 661 347 and SH 661 348)

This hill’s P30 status also affects the Tumps, the author of this list; Mark Jackson is not in immediate receipt of these data, but I’m sure he will be made aware of the result and its implication.

Foel Penolau was surveyed over two days; 17^th November and 26^th November 2018, with the first survey conducted with Aled Williams and this consisted of two bwlch data sets on the hill to hill traverse and a data set taken on both the southerly and northerly summit of this hill.  Whilst the second survey concentrated on the area of this hill’s bwlch with a further seven data sets being taken.

The Ordnance Survey Interactive Coverage Map hosted on the Geograph website gives a 588m spot height positioned at SH 66058 34637, and this is the only spot height that appears on maps for the area of this hill’s connecting bwlch to Moel Ysgyfarnogod (SH 658 345), and when coupled with the 614m summit spot height gives this hill 26m of drop which is insufficient for Simm, Hewitt and Twmpau status.

Two data sets were taken in the area close to where this spot height appears on the ground, both on the hill to hill traverse with each either side of a slight rise, these results appear below (with all forthcoming results converted to OSGM15):

17.11.18:  586.826m at SH 66009 34640

26.11.18:  587.302m at SH 66064 34662

The conclusion from there data is that the 588m spot height is positioned on the slight rise and therefore is dismissed from this hill’s drop value.

The southern aspect of Foel Penolau is impressive as it rises as a vertical cliff which over many years has crumbled depositing large boulders at its base, and it is this boulder field where the critical bwlch of Foel Penolau is positioned.

The Trimble GeoXH 6000 gathering data in the boulder field

The boulder field is complicated as large holes are evident, these are positioned beside and also under many of these boulders, and therefore it was this boulder field that first coined the term of whether a critical bwlch should be taken from an ant’s or human’s perspective.  I adopted an ant’s perspective and took a series of measurement offsets to solid ground at the base of each set-up position, in many instances these were to gaping holes under the large boulders.  However, one data set was taken on to grass to where the land on the hill to hill traverse enters the boulder field, this result is:

26.11.18:  583.370m at SH 66097 34731

The remaining data sets taken at the bwlch were all in the boulder field and on the valley to valley traverse, their results from west to east are:

26.11.18:  581.942m at SH 66091 34746

26.11.18:  582.411m at SH 66094 34739

17.11.18:  582.482m at SH 66099 34735

26.11.18:  582.176m at SH 66105 34730

26.11.18:  582.006m at SH 66117 34721

26.11.18:  581.725m at SH 66127 34717

Therefore the critical bwlch as surveyed by the Trimble is positioned at SH 66099 34735 and its height is 582.482m.  This is the position that Aled and I surveyed on the 17.11.18.

Aled at the critical bwlch of Foel Penolau as surveyed with the Trimble with the measurement offset being 1.79m

Foel Penolau is given two 614m summits of equal height on contemporary Ordnance Survey maps, their connecting bwlch and both summits were also surveyed, resulting in:

17.11.18:  614.379m at SH 66145 34774 (southerly summit)

17.11.18:  604.482m at SH 66154 34788 (connecting bwlch between summits)

17.11.18:  614.380m at SH 66184 34832 (northerly summit)

The 1mm difference between each summit produced by the Trimble GeoXH 6000 is outside the tolerance levels of this equipment and therefore they remain twin summits for now.

The Trimble GeoXH 6000 at the northerly summit of Foel Penolau

Therefore the survey results produced by the Trimble GeoXH 6000 for Foel Penolau are as follows:

614.4m summit at SH 66145 34774 and SH 66184 34832

582.5m bwlch at SH 66099 34735

With these values giving this hill 31.9m of drop and confirming its reclassification to Simm, Hewitt and Twmpau status.

Myrddyn Phillips (December 2018)

   

Grough article announcing the new Hewitt and Simm status of Foel Penolau  

UKHillwalking article announcing the new Hewitt and Simm status of Foel Penolau