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

Exford South Common (SS 808 374)

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 Exford South Common (SS 808 374)

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; the 400m Sub-Fours, the 390m Sub-Fours and the 390m Double Sub-Fours.  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 name the hill is listed by is Exford South Common and this was derived from the Tithe map, and it is adjoined to the Dunkery Beacon group of hills, which are situated in Exmoor in the county of Somerset, and it is positioned with the B3224 road to its north and minor roads to its west and east, and has the villages of Simonsbath to the west north-west and Exford to the east north-east.

When the 1^st edition of the The Fours was published by Europeaklist in December 2013, this hill was listed with 35m of drop, based on the 412m summit spot height positioned at SS 809 375 and the 377m col spot height that appear on the contemporary Ordnance Survey 1:25,000 Explorer map.

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

However, it was not until LIDAR became available that the details for the summit of 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 Exford South Common (SS 808 374)

LIDAR analysis gives the highest ground on this hill as 411.6m positioned at SS 80892 37483,  and as this position is in a different field compared to where the spot height appears it comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies to when the high point is positioned in a different field, to a different feature such as a conifer plantation, within a different map contour, a different point where a number of potential summit positions are within close proximity, when natural ground or the natural and intact summit 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 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 411.6m and this is positioned at SS 80892 37483.  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 42 metres south-westward from where the previously listed summit is positioned.

The full details for the hill are:

Group:  Dunkery Beacon

Name:  Exford South Common

OS 1:50,000 map:  181

Summit Height:  411.6m (LIDAR)

Summit Grid Reference (New Position):  SS 80892 37483 (LIDAR)  

Col Height:  377.2m (LIDAR)

Col Grid Reference:  SS 80338 38959 (LIDAR)

Drop:  34.4m (LIDAR)

Myrddyn Phillips and Aled Williams (July 2018)