Mapping Mountains – Summit Relocations – The Welsh P15s

 

Ffridd (SN 730 979) 

There has been a Summit Relocation to a hill that is listed in the The Welsh P15s, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Ffridd (SN 730 979)

The criteria for the list that this summit relocation applies to are:

The Welsh P15s – Welsh hills with 15m minimum drop, irrespective of their height, with an accompanying sub list entitled the Welsh Sub-P15s, with the criteria for this sub category being all Welsh hills with 14m or more and below 15m of drop.  The list is authored by Myrddyn Phillips, with the Introduction to the list appearing on Mapping Mountains on the 10^th May 2019. 

The Welsh P15s by Myrddyn Phillips

The name the hill is listed by is Ffridd and this was derived from the Tithe map, and it is adjoined to the Banc Llechwedd Mawr group of hills, which are situated in the north-western part of South Wales (Region B, Sub-Region B1), and it is positioned with the A487 road to its north-west and minor roads to its south and east, and has the town of Machynlleth towards the north north-east.

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was not included in the accompanying Hills to be surveyed sub list, as it was considered not to meet the criteria then used for this sub category. 

Extract from the Ordnance Survey 1:25,000 Explorer map

After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed with an estimated c 22m of drop, based on the twin 216m summit spot heights positioned at SN 72979 97898 and SN 73120 98126 that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map and an estimated c 194m bwlch height, based on interpolation of 10m contouring between 190m – 200m.

However, it was not until LIDAR became available that the details for this hill could be accurately re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales. 

LIDAR summit image of Ffridd (SN 730 979)

LIDAR analysis gives the highest ground on this hill as 209.7m positioned at SN 73032 97996, with LIDAR also giving 206.6m positioned at SN 73124 98128 which corresponds to the position of the northerly of the two spot heights that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map.  As LIDAR analysis has de-twinned the summit of this hill this comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies when the high point of the hill is found to be positioned; in a different field, to a different feature such as in a conifer plantation,  within a different map contour either on Ordnance Survey maps or interactive mapping, to a different point where a number of potential summit positions are within close proximity, when natural ground or the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary or covered reservoir that is considered a relatively recent man-made construct, or the de-twinning of a summit, or a relocation of approximately 100 metres or more in distance from either the position of a map spot height or from where the summit of the hill was previously thought to exist.

Therefore, the summit height produced by LIDAR analysis is 209.7m and is positioned at SN 73032 97996, this position is approximately 132 metres south-westward from the position of the lower of what were previously listed as twin summits that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

 

The full details for the hill are:

Group:  Banc Llechwedd Mawr 

Name:  Ffridd 

OS 1:50,000 map:  135

Summit Height:  209.7m (LIDAR) 

Summit Grid Reference (New Position):  SN 73032 97996 (LIDAR) 

Bwlch Height:  193.9m (LIDAR) 

Bwlch Grid Reference:  SN 72854 98987 & SN 72854 97990 (LIDAR) 

Drop:  15.8m (LIDAR) 

 

Myrddyn Phillips (July 2025)