Mapping Mountains – Summit Relocations – Y Pedwarau

Bryn Serth (SO 148 109)  

There has been a Summit Relocation to the listing of Y Pedwarau initiated from a survey with the Trimble GeoXH 6000 and subsequently confirmed from LIDAR analysis, with the latter conducted by Aled Williams.  The list of the Y Pedwarau takes in all 400m Welsh hills that have a minimum drop of 30m, with the Trimble survey that resulted in the following details taking place on 12^th August 2015.

Accompanying the Y Pedwarau list are a number of sub category's of hills, with this hill being listed as a 400m Sub-Pedwar, these are the Welsh 400m hills that have 20m or more and below 30m of drop.

The hill is positioned in the group known as Cymoedd Gwent in south Wales, and it was surveyed during a walk in the company of Mark Trengove on a bright and cheerful day.  The hill is situated on the northern outskirts of Tredegar at the head of the Cwm Sirhywi (Sirhowey Valley) and it can be easily accessed from a car park beside the busy A4047 which is positioned at its south-eastern base.  This car park also gives access to the Aneurin Bevan Memorial Stones; these consist of four monoliths and are set against the landscape of Ebbw Vale, Tredegar and Rhymney which form the constituencies which Aneurin Bevan represented during his years in Westminster.

The name of the hill is Bryn Serth and prior to the survey with the Trimble GeoXH 6000 it was listed as a Pedwar with its summit position given as SO 147 108 which is the centralised position of its uppermost 410m ring contour that appears on current Ordnance Survey maps, with this ring contour being erroneous as there is no land on this hill that reaches the height of this contour.  However, this position is not the high point of the hill as land approximately 100 metres further north was surveyed by the Trimble as being 2.0m higher.

The position of the relocated summit is at SO 14807 10929 and is the top of featureless ground that mainly consists of long grass, this position is not given a spot height on contemporary Ordnance Survey maps but the Trimble and LIDAR result gave it as 2.0m higher when compared to the land where the uppermost ring contour appears on the ground.

The full details for the hill are:

Group:  Cymoedd Gwent

Summit Height:  404.0m (LIDAR)

Name:  Bryn Serth

OS 1:50,000 map:  161

Summit Grid Reference (New Position):  SO 14807 10929 (LIDAR)

Drop:  25.8m (LIDAR)

The Trimble GeoXH 6000 set-up position at the summit of Bryn Serth, with the old position of the summit in the background of this photograph

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

Myrddyn Phillips and Aled Williams (August 2015)