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

Reilth Top (SO 284 881) 

There has been confirmation 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 and LIDAR analysis conducted by Myrddyn Phillips and Aled Williams. 

Reilth Top (SO 284 881)

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 being included 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 name the hill is listed by is Reilth Top, 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 encircled by minor roads, with the B4385 road farther to its north, the A489 road farther to its north-west, the B4368 road farther to its south and the A488 road farther to its east, and has the town of Bishop’s Castle towards the east.

When the 1^st edition of the The Fours was published by Europeaklist in December 2013, this hill was listed with an estimated c 30m of drop and with an estimated c 406m summit height positioned at SO 284 881, and it was this position that was also given for the summit of this hill when the 2^nd edition of the The Fours – The 400m Hills of England was published by Mapping Mountains Publications in April 2018, with the drop value being amended to 29.3m. 

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

However, although the natural summit of this hill has been surveyed with the Trimble GeoXH 6000 it was not until LIDAR became available that the 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. 

The Trimble GeoXH 6000 gathering data at the natural summit of Reilth Top

The raised field boundary

LIDAR analysis gives the highest ground on this hill as 405.0m positioned at SO 28427 88095.  However, this is a part of a raised field boundary and protocols dictate that as this is deemed a relatively recent man-made construct such ground is discounted from the height of a hill. 

LIDAR image of Reilth Top (SO 284 881)

The height produced by the Trimble GeoXH 6000 survey to the natural summit of this hill is 404.6m positioned at SO 28458 88105, and this position in relation to the raised field boundary 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. 

LIDAR summit image of Reilth Top (SO 284 881)

Therefore, the summit height produced by the Trimble GeoXH 6000 survey is 404.6m and this is positioned at SO 28458 88105.  This position is given a spot height on the contemporary Ordnance Survey 1:50,000 Landranger map and is within the uppermost 405m contour ring that appears on the 1:25,000 Explorer map and is approximately 30 metres eastward from the high point of the raised field boundary.

 

The full details for the hill are:

Group:  Cilfaesty

Name:  Reilth Top

OS 1:50,000 map:  137

Summit Height:  404.6m (Trimble GeoXH 6000)

Summit Grid Reference (New Position):  SO 28458 88105 (Trimble GeoXH 6000)

Col Height:  375.4m (LIDAR)

Col Grid Reference:  SO 28878 87840 (LIDAR)

Drop:  29.2m (Trimble GeoXH 6000 summit and LIDAR col)

 

Myrddyn Phillips and Aled Williams (December 2023)