Mapping Mountains – Summit Relocations – The Fours - The 400m Hills of England

Cefn Fron (SO 165 838)

There has been a Summit Relocation to a hill that is listed in the The Fours – The 400m Hills of England, with the summit height, col height and their locations, the drop and status of the hill derived from LIDAR analysis initially conducted by Aled Williams and subsequently by Myrddyn Phillips.

LIDAR image of Cefn Fron (SO 165 838)

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

The Fours – The 400m Hills of England.  English hills at or above 400m and below 500m in height that have 30m minimum drop, accompanying the main list are three categories of sub hills, with this hill classified in the 400m Sub-Four category, the criteria for which are all English hills at or above 400m and below 500m in height that have 20m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and the 2^nd edition of the booklet containing this list was published by Mapping Mountains Publications on the 24^th April 2018.

The Fours - The 400m Hills of England by Myrddyn Phillips and Aled Williams

The hill is adjoined to the Cilfaesty group of hills, which are situated in the Welsh borders, and it is positioned with the B4368 road to its north and the B4355 road to its south, and has the small community of Felindre towards the south and the town of Trefyclo (Knighton) towards the south-east.

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

When the 1^st edition of the The Fours was published by Europeaklist in December 2013, this hill was listed as a 400m Sub-Four with 22m of drop, based on the 414m summit spot height positioned at SO 166 840 and the 392m col spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map.

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map with the summit position ascertained from initial LIDAR analysis circled

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 Cefn Fron (SO 165 838)

Initial LIDAR analysis gave the summit position as SO 16547 83808, with the latest available LIDAR giving the highest ground on this hill as 415.6m positioned at SO 16549 83829, and 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, 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 judged to be a relatively recent man-made construct, 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 the latest LIDAR analysis is 415.6m and this is positioned at SO 16549 83829.  This position is not given a spot height on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and is approximately 170 metres southward from where the previously listed summit was positioned.

The full details for the hill are:

Group:  Cilfaesty

Name:  Cefn Fron

OS 1:50,000 map:  136

Summit Height:  415.6m (LIDAR)

Summit Grid Reference (New Position):  SO 16549 83829 (LIDAR)

  

Col Height:  391.65m (LIDAR)

Col Grid Reference:  SO 16752 84287 (LIDAR)

Drop:  23.9m (LIDAR)

Myrddyn Phillips and Aled Williams (July 2018)