Wednesday 13 December 2023

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


Dowke Hill (SO 224 806) 

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 LIDAR analysis conducted by Aled Williams and Myrddyn Phillips. 

LIDAR image of Dowke Hill (SO 224 806)

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

The FoursThe 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 2nd edition of the booklet containing this list was published by Mapping Mountains Publications on the 24th April 2018.

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

The name the hill is listed by is Dowke 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 encircled by minor roads, with the B4368 road farther to its north, the B4355 road farther to its south-west and the A488 road farther to its east south-east, and has the town of Clun towards the east.

When the 1st edition of the The Fours was published by Europeaklist in December 2013, this hill was listed with an estimated c 33m of drop and with a 416m summit height positioned at SO 224 806.  When the 2nd edition of the The Fours – The 400m Hills of England was published by Mapping Mountains Publications in April 2018, this hill had been analysed via LIDAR, resulting in a 417.0m summit height positioned at SO 224 806. 

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

However, it was not until the latest LIDAR coverage 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 analysis gives the highest ground on this hill as 417.4m positioned at SO 22452 80672.  However, this is a part of a hedge incorporated in 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 summit image of Dowke Hill (SO 224 806)

The height produced by the latest LIDAR analysis to the natural summit of this hill is 417.2m positioned at SO 22447 80675, 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.

Therefore, the summit height produced by the latest LIDAR analysis is 417.2m and this is positioned at SO 22447 80675.  This position is close to where the 416m spot height appears on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and is approximately 5 metres westward from the high point of the hedge incorporated in the raised field boundary.

 

The full details for the hill are:

Group:  Cilfaesty

Name:  Dowke Hill

OS 1:50,000 map:  137

Summit Height:  417.2m (LIDAR)

Summit Grid Reference (New Position):  SO 22447 80675 (LIDAR)

Col Height:  383.6m (LIDAR)

Col Grid Reference:  SO 21653 80934 (LIDAR)

Drop:  33.5m (LIDAR)

 

Myrddyn Phillips and Aled Williams (December 2023)

  

No comments: