Mapping Mountains – Summit Relocations – Y Pedwarau

Banc Bron Derwgoed (SN 871 987)  

There has been a Summit Relocation to the listing of Y Pedwarau initiated by a survey with the Trimble GeoXH 6000, with the survey that resulted in the following details taking place on 7^th September 2015.  The Y Pedwarau are the 400m Welsh hills that have 30m minimum drop.

Accompanying the main Y Pedwarau list are a series of sub lists, with this hill now being listed as a 400m Sub-Pedwar, these are the 400m hills of Wales that have 20m or more and below 30m of drop.

The hill is situated in the Pumlumon range and the survey was conducted in the company of Aled Williams, who had suggested the walk.  The hill is positioned to the south-west of the small communities of Llan and Bont Dolgadfan, and can be easily accessed from a minor road to the north-west of the summit, however the hills of the northern Pumlumon range are highly recommended and it is worthwhile considering an extended walk taking in this hill and other neighbouring summits.

The name of the hill is Banc Bron Derwgoed and prior to the Trimble survey it was listed as a Pedwar with its summit position given as SN 872 988 which is where the 404m spot height appears on current Ordnance Survey maps.  However, this position is not the high point of the hill as land approximately 80 metres further west was surveyed by the Trimble as being 0.4m higher.

Three positions on the area of this hill’s summit were surveyed, the results appear below:

1^st position:  403.754m (converted to OSGM15) at SN 87250 98813

2^nd position:  403.988m (converted to OSGM15) at SN 87205 98770

3^rd position:  404.182m (converted to OSGM15) at SN 87154 98796

The first position surveyed with the Trimble GeoXH 6000 equates to the approximate high ground where the 404m spot height appears on current Ordnance Survey maps.

The position of the relocated summit is at SN 87154 98796 and is the top of a grassy knoll which is the first high point when approaching the summit of the hill from the north-west.  This position is not given a spot height on current Ordnance Survey maps.

The full details for the hill are:

Cardinal Hill:  Foel Fadian

Summit Height:  404.2m (converted to OSGM15)

Name:  Banc Bron Derwgoed

OS 1:50,000 map:  135, 136

Summit Grid Reference (New Position):  SN 87154 98796

Drop:  27.7m (converted to OSGM15)

The Trimble GeoXH 6000 gathering data at the old summit position of Banc Bron Derwgoed, with the new position of the summit on the central grassy ridge on the right of this photograph

For details on the survey that relocated the summit of this hill please click {here}

Myrddyn Phillips and Aled Williams (September 2015)