Saturday, 27 December 2014

Mapping Mountains – Hill Reclassifications – Y Pedwarau

Mynydd Poeth (SH 953 513) - 400m Sub-Pedwar reclassified to Pedwar

There has been a reclassification of a 400m Sub-Pedwar to a Pedwar recently discovered by surveying with the Trimble GeoXH 6000.  The hill is situated in the Mynydd Hiraethog range and is positioned north of Cerrigydrudion and south of Llyn Brenig.

The hill is named Mynydd Poeth (SH 953 513), and it had two possibilities for the position of its critical bwlch, one to the west and another to its east of its summit, with both leading to higher ground and both with bwlch contouring on Ordnance Survey maps between 380m – 390m.

Mynydd Poeth (417m summit spot height on Ordnance Survey maps) had been listed as a 400m Sub-Pedwar with c 29m of drop based on the critical bwlch being east of the summit at SH 957 509 and with an estimated height of c 388m, with its western bwlch at SH 950 513 having an estimated height of c 387m.  The hill is currently listed as a Tump by Mark Jackson with 30m of drop based on its critical bwlch being placed at SH 950 512.

Each bwlch position was surveyed with the following results:

Eastern bwlch:  387.6m (converted to OSGM15) at SH 95707 50953.

Western bwlch:  386.9m (converted to OSGM15) at SH 95069 51315.

Although the estimation of each bwlch height is in good accordance with the survey result produced by the Trimble GeoXH 6000, the hill qualifies for Pedwar status as the known summit height has increased by 2.3m from its 417m map height at SH 95403 51068 to its summit position at SH 95375 51301 which has a height of 419.300m (converted to OSGM15).

This now brings the overall total for the Y Pedwarau to 452 hills with five additions since publication of the list by Europeaklist in May 2013.  The hill will be added to the Y Pedwarau list in the 2nd edition that will hopefully be published by Europeaklist.  The list of Pedwar hills is also available from the Haroldstreet website.

The full details for the hill are:

Cardinal Hill:  Mwdwl-eithin

Summit Height:  419.3m (converted to OSGM15)

Name:  Mynydd Poeth

OS 1:50,000 map:  116

Summit Grid Reference:  SH 953 513

Drop:  31.7m (converted to OSGM15)

Mynydd Poeth (SH 953 513) has now been confirmed as a Pedwar
For details on the survey that reclassified this hill to Pedwar status please click {here}

Myrddyn Phillips and Aled Williams (December 2014)

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