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

Bryn Hill (SO 295 862) 

There has been confirmation via LIDAR analysis of 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 a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips. 

LIDAR image of Bryn Hill (SO 295 862)

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 Bryn Hill, and it is adjoined to the Cilfaesty group of hills, which are situated in the county of Shropshire close to the Welsh border, and it is positioned with minor roads to its north-west and south, with the A488 road to its east, and has the town of Bishop’s Castle towards the north-east.

When the 1^st edition of the The Fours was published by Europeaklist in December 2013, this hill was listed with 109m of drop and with a 408m summit height positioned at SO 294 862.  When the 2^nd edition of the The Fours – The 400m Hills of England was published by Mapping Mountains Publications in April 2018, the hill had been surveyed with the Trimble GeoXH 6000, resulting in a 407.5m summit height positioned at SO 295 862. 

The Trimble GeoXH 6000 gathering data at the natural summit of Bryn Hill

However, although the natural summit of this hill has been surveyed with the Trimble GeoXH 6000 it was not until LIDAR became available that other numerical 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 Bryn Hill (SO 295 862)

LIDAR analysis gives the highest ground on this hill as 408.9m positioned at SO 29494 86204.  However, this is a part of a raised field boundary that incorporates a water tank and protocols dictate that as this is deemed a relatively recent man-made construct such ground is discounted from the height of a hill.

The height produced by the Trimble GeoXH 6000 survey to the natural summit of this hill is 407.5m positioned at SO 29550 86222, and this position in relation to the raised field boundary and water tank 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 the Trimble GeoXH 6000 survey is 407.5m and this is positioned at SO 29550 86222.  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 56 metres eastward from the high point of the raised field boundary incorporating the water tank which is where the 408m spot height appears on the contemporary Ordnance Survey 1:25,000 Explorer map.

 

The full details for the hill are:

Group:  Cilfaesty

Name:  Bryn Hill

OS 1:50,000 map:  137

Summit Height:  407.5m (Trimble GeoXH 6000)

Summit Grid Reference (New Position):  SO 29550 86222 (Trimble GeoXH 6000)

Col Height:  298.9m (Trimble GeoXH 6000)

Col Grid Reference:  SO 29299 86584 (Trimble GeoXH 6000)

Drop:  108.6m (Trimble GeoXH 6000)

 

Myrddyn Phillips and Aled Williams (December 2023)