Monday, 31 August 2015

Mapping Mountains – Significant Height Revisions – Y Pedwarau

Mynydd Poeth (SH 953 513)

This is the twelfth post under the heading of Significant Height Revisions, and the following details are retrospective as the Trimble survey that resulted in this height revision was conducted on 24th December 2014.

The twelfth major height revision initiated from a survey with the Trimble GeoXH 6000 was conducted in the Mynydd Hiraethog hills in north Wales on Christmas Eve, in the company of Mark Trengove who had suggested the walk.

The hill appeared in the listing of Y Pedwarau as a Sub-Pedwar with c 29m of drop and was reclassified to a Pedwar due to the survey with the Trimble.  The hill can be easily accessed from the B4501 which skirts its eastern fringes, and is situated just to the north of Cerrigydrudion and to the south of the Alwen Reservoir.

The name of the hill is Mynydd Poeth and its summit height has been increased from its current Ordnance Survey map height, as prior to the survey with the Trimble GeoXH 6000 the hill was listed with a summit height of 417m based on the spot height that appears on current Ordnance Survey maps.  However, higher ground exists to the north of where the 417m spot height appears on the ground.

Therefore this hill’s new summit height is 419.3m (converted to OSGM15) which is 2.3m higher than its previously listed height which came from the 417m spot height on current Ordnance Survey maps.

This hill is one of the rare few that can claim a Hill Reclassification, Summit Relocation and a Significant Height Revision all from the one survey.

The full details for the hill are:

Cardinal Hill:  Mwdwl Eithin

Summit Height (New Height):  419.3m (converted to OSGM15)

Name:  Mynydd Poeth

OS 1:50,000 map:  116

Summit Grid Reference:  SH 95375 51301
Drop:  31.7m

Gathering data from the summit of Mynydd Poeth which resulted in this hill's significant height revision

For details on the survey that significantly revised the summit height of this hill please click {here}

Myrddyn Phillips and Aled Williams (December 2014)

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