Mapping Mountains – Summit Relocations – The Fours

Knot (NY 650 091)

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 analysis conducted by Myrddyn Phillips.

LIDAR image of Knot (NY 650 091)

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 Knot and it is situated in The Northern and Central Pennines (Region 35, Section 35A), and is positioned with the A66 road to its north-east, the M6 motorway to its west and the A685 road to its south and has a number of minor roads encircling it, and has the small community of Orton towards the west south-west and Great Asby towards the north-east.

When the 1^st edition of the The Fours was published by Europeaklist in December 2013, the summit of this hill was listed as 412m and its prioritised position given as NY 646 092, based on the position of a triangulation pillar which is given a 412.699m flush bracket height at NY 64696 09226 in the OS Trig Database.

The summit area of this hill has two uppermost 410m ring contours, aligned west - east, with a 412m spot height given to the triangulation pillar which is based in the western ring contour, whilst the eastern ring contour has a second 412m spot height that appears on the Ordnance Survey 1:25,000 Explorer map.

Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website with the summit position circled

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 analysis gives the highest ground on this hill as 413.1m positioned at NY 65064 09121, as opposed to the highest ground near the triangulation pillar which LIDAR gives as 412.4m positioned at NY 64694 09204, 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.The highest land in each of these ring contours was analysed via LIDAR by Myrddyn Phillips.  The LIDAR (Light Detection & Ranging) technique is highly accurate height data that is now freely available for much of England and Wales.

Therefore, the summit height produced by LIDAR analysis is 413.1m and this is positioned at NY 65064 09121.  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 370 metres eastward from where the previously listed summit is positioned.

 

The full details for the hill are:

Group:  Tarn Crag

Name:  Knot

OS 1:50,000 map:  91

Summit Height:  413.1m (LIDAR)

Summit Grid Reference (New Position):  NY 65064 09121 (LIDAR)

Col Height:  279.0m (LIDAR)

Col Grid Reference:  NY 56898 11385 (LIDAR)

Drop:  134.1m (LIDAR)

Myrddyn Phillips and Aled Williams (May 2018)