Mapping Mountains – Significant Height Revisions – Y Pedwarau

Bryn Melyn (SO 109 184)

There has been a Significant Height Revision to a hill listed in the Y Pedwarau initiated from a survey with the Trimble GeoXH 6000, with these details being retrospective as the survey that resulted in this height revision was conducted on the 22^nd July 2014.  With the criteria for Pedwar status being all Welsh hills at or above 400m and below 500m in height that have a minimum 30m of drop.

The name of the hill is Bryn Melyn and it is situated in the Bannau Brycheiniog (Brecon Beacons) range of hills in south Wales, with the survey of the hill conducted in the company of Mark Trengove who had suggested the walk.

Bryn Melyn can be easily accessed from the end of a minor road above the waters of the Talybont Reservoir which is situated in Glyn Collwn.  The hill can also be accessed from its opposing valley of Dyffryn Crawnon which gives a slightly more rewarding and lengthy walk.

This hill's 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 an estimated summit height of c 446m based on it having an uppermost contour ring of 440m on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps.  Its new summit height is 450.5m (converted to OSGM15) which is 4.6m higher than its previously estimated height and 10.5m higher than its uppermost ring contour on current Ordnance Survey maps.

The full details for the hill are:

Cardinal Hill:  Pen y Fan

Summit Height (New Height):  450.5m (converted to OSGM15)

Name:  Bryn Melyn

OS 1:50,000 map:  161

Summit Grid Reference:  SO 10941 18432

  

Drop:  38.2m (Trimble summit and LIDAR bwlch)

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

For details on the survey that significantly revised the summit height of this hill

Myrddyn Phillips and Aled Williams (August 2015)