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

Bowland Knotts (SD 727 606) 

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 Myrddyn Phillips. 

LIDAR image of Bowland Knotts (SD 727 606)

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-Four category, the 390m Sub-Four category and the 390m Double Sub-Four category.  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 Bowland Knotts, and it is adjoined to the Ward’s Stone group of hills, which are situated in the southern Pennines, and it is positioned with a minor road to its immediate west, the B6478 road to its south-east and the A65 road to its north-east, and has the town of Settle towards the east north-east.

When the original list that later became known as The Fours – The 400m Hills of England was first compiled, the summit position of this hill was given as SD 722 603 based on the 430m map heighted triangulation pillar that appears on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map. 

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

When the 1^st edition of the The Fours was published by Europeaklist in December 2013, the summit of this hill was relocated to SD 727 606 and listed with an estimated c 86 of drop, based on an estimated c 430m summit height and an estimated c 344m col height, with both heights based on interpolation of 10m contouring that appear on the Ordnance Survey 1:25,000 Explorer map.

The following note accompanied its listing:

As there is no 430m contour ring in the vicinity of the triangulation pillar that has a flush racket height of 429.932m (highest ground in vicinity of trig is at SD 722 603) the listed summit has been relocated to the vicinity of where a c 430m contour ring is shown on the map.  Therefore the summit is relocated from the previously listed high point which appeared in the original published listing in the RHB Yahoo Group file database.  However, margin of uncertainty associated with contour lines means the ground at SD 722 603 in the vicinity of the trig is still a contender as overall high point.

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 Bowland Knotts (SD 727 606)

LIDAR analysis gives the highest ground on this hill as 430.7m positioned at SD 72767 60678, as opposed to the originally listed summit position which LIDAR gives as 430.0m positioned at SD 72207 60305, 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 430.7m and this is positioned at SD 72767 60678.  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 570 metres north-eastward from where the original listed summit is positioned.

 

The full details for the hill are:

Group:  Ward’s Stone

Name:  Bowland Knotts

OS 1:50,000 map:  98

Summit Height:  430.7m (LIDAR)

Summit Grid Reference (New Position):  SD 72767 60678 (LIDAR)

Col Height:  343.4m (LIDAR)

Col Grid Reference:  SD 71799 60697 (LIDAR)

Drop:  87.3m (LIDAR)

 

Myrddyn Phillips and Aled Williams (May 2023)