Mapping Mountains – Significant Name Changes – The Welsh P15s

Foel Fach (SN 688 955) 

There has been a Significant Name Change to a hill that is listed in 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 Foel Fach (SN 688 955)

The criteria for the list that this name change 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 hill 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 minor roads to its north and south, and the A487 road to its west, and has the town of Machynlleth towards the north-east.

When the listing that became known as The Welsh P15s was being compiled, this hill was not included in either the main list or the accompanying sub list, and was subsequently documented with an estimated c 9m of drop and listed under the point (Pt. c 58m) notation, based on an estimated c 58m summit height and an estimated c 49m bwlch height, with both heights based on interpolation of 10m contouring that appears on the Ordnance Survey 1:25,000 Explorer map. 

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

Since the original compilation of this list there have been a number of maps made available online.  Some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website.  Whilst others were digitally updated such as the Ordnance Survey Vector Map Local that was hosted on the Geograph website and which was entitled the Interactive Coverage Map, whilst others are current and digitally updated such as the interactive mapping on the Magic Maps and WalkLakes websites, and it is the series of Ordnance Survey Six-Inch maps that form the basis of the change in the listed name of this hill.

The Ordnance Survey series of Six-Inch maps formed the base map Ordnance Survey used for many decades leading to the production of the 1:10,000 Series of maps, both have now been superseded by the digitised Master Map.  The series of Six-Inch maps are excellent for name placement and especially so compared to the contemporary Ordnance Survey 1:25,000 Explorer map, and it is the series of Six-Inch maps that position the name of Foel Fach to land where the summit of this hill is situated.

Extract from the Ordnance Survey series of Six-Inch maps

Therefore, the name this hill is now listed by in the The Welsh P15s is Foel Fach, and this was derived from the Ordnance Survey series of Six-Inch maps.

 

The full details for the hill are: 

Group:  Banc Llechwedd Mawr 

Name:  Foel Fach 

Previously Listed Name:  Pt. c 58m 

OS 1:50,000 map:  135

Summit Height:  65.4m (LIDAR)                                                           

Summit Grid Reference:  SN 68831 95574 (LIDAR)                                                  

Bwlch Height:  46.1m (LIDAR) 

Bwlch Grid Reference:  SN 68880 95570 (LIDAR) 

Drop:  19.3m (LIDAR) 

 

Myrddyn Phillips (October 2025)