Thursday, 18 May 2023

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


Highfolds (SD 894 677) 

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 conducted by Myrddyn Phillips. 

LIDAR image of Highfolds (SD 894 677)

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, 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 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 Highfolds and it is adjoined to the Pen y Ghent group of hills, which are situated in the central Pennines, and it is positioned with minor roads to its north-east, north-west and south, and the B6160 road to its east, and has the village of Malham towards the south.

When the 1st edition of the The Fours was published by Europeaklist in December 2013, this hill was listed with an estimated c 21m of drop, based on the 474m summit spot height positioned at SD 89329 67847 that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 453m col height, based on interpolation of 10m contouring between 450m – 460m. 

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

When the 2nd edition of the The Fours – The 400m Hills of England was published by Mapping Mountains Publications in April 2018, the details given above remained the same except for the drop value being amended to an estimated c 22m, based on interpolation of 5m contouring between 450m – 455m that appeared on the interactive mapping on the OS Maps website.

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 Highfolds (SD 894 677)

LIDAR analysis gives the highest ground on this hill as 473.713m positioned at SD 89456 67796, as opposed to the originally listed summit position which LIDAR gives as 473.653m positioned at SD 89342 67876, and this 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 477.7m and this is positioned at SD 89456 67796.  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 115 metres south-eastward from where the original listed summit is positioned.

 

The full details for the hill are:

Group:  Pen y Ghent

Name:  Highfolds

OS 1:50,000 map:  98

Summit Height:  473.7m (LIDAR)

Summit Grid Reference (New Position):  SD 89456 67796 (LIDAR)

Col Height:  452.5m (LIDAR)

Col Grid Reference:  SD 89406 68117 (LIDAR)

Drop:  21.2m (LIDAR)

 

Myrddyn Phillips and Aled Williams (May 2023) 

No comments: