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

Great Castle How (NY 307 078) 

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 prompted by Joe Nuttall who produced a summit analysis programme using LIDAR, and then confirmed by LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Great Castle How (NY 307 078)

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 Great Castle How and it is adjoined to the High Raise group of hills, which are situated in The Lake District (Region 34, Section 34B: The Central and Western Fells), and it is positioned with the B5343 road to its south and the A591 road to its east, and has the village of Grasmere towards the east.

When the 2^nd edition of the The Fours – The 400m Hills of England was published by Mapping Mountains Publications in April 2018, this hill was not included in the accompanying sub list, as it was considered not to meet the criteria used for this sub category.  With its drop to an adjacent and connecting 500m spot heighted hill which was listed as a Subdodd considered insufficient for qualification. 

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

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 Great Castle How (NY 307 078)

LIDAR analysis gives the highest ground on this hill as 498.2m positioned at NY 30791 07836, as opposed to the summit of the previously listed Subdodd which LIDAR gives as 497.7m in height positioned at NY 30773 07598, and this comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies when the high point of the hill is found to be positioned; in a different field, to a different feature such as in a conifer plantation,  within a different map contour, to a different point where a number of potential summit positions are within close proximity, when natural ground or the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary or covered reservoir that is judged to be 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 498.2m and this is positioned at NY 30791 07836.  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 240 metres northward from where the previously listed summit is positioned. 

 

The full details for the hill are:

Group:  High Raise

Name:  Great Castle How

OS 1:50,000 map:  90

Summit Height:  498.2m (LIDAR)

Summit Grid Reference (New Position):  NY 30791 07836 (LIDAR)

Col Height:  472.1m (LIDAR)

Col Grid Reference:  NY 30551 07712 (LIDAR)

Drop:  26.0m (LIDAR)

 

Our thanks to Ronnie Bowron for bringing the details of this hill to our attention.

Myrddyn Phillips and Aled Williams (November 2022)