Mapping Mountains – Hill Reclassifications – The Fours – The 400m Hills of England

 

Warrendale Knotts (SD 836 643) – Sub-Four addition

There has been an addition to the listing of 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 Warrendale Knotts (SD 836 643)

The criteria for the list that this addition 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 is a sub list entitled the Sub-Fours, the criteria for which are all English hills at or above 400m and below 500m in height that have 15m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is available to download in Google Doc format from the Mapping Mountains site.

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

The name the hill is listed by is Warrendale Knotts, and it is adjoined to the Pen y Ghent group of hills, which are situated in the Pennines of northern England, and it is positioned encircled by minor roads, with the B6479 road and B6480 road farther to its west, and has the town of Settle towards the west south-west.

When the Introduction to the first group of hills for the updated and revised listing of the The Fours – The 400m Hills of England was published by Mapping Mountains on the 10^th September 2022, it was announced that the accompanying sub lists were being revised with the two 390m categories dispensed with and the criteria and name of the 400m Sub-Fours revised.  The one accompanying sub list is now named the Sub-Fours with its criteria being all English hills 400m and above and below 500m in height that have 15m and more and below 30m of drop.

Prior to this revision this hill was not listed, with subsequent interpolation giving it an estimated c 13m of drop, based on an estimated c 416 summit height and an estimated c 403m col height, with both heights based on interpolation of 10m contouring that appear on the Ordnance Survey 1:25,000 Explorer map. 

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.

Therefore, the addition of this hill to Sub-Four status is due to LIDAR analysis, resulting in a 417.2m summit height and a 401.0m col height, with these values giving this hill 16.3m of drop, which is sufficient for it to be classified as a Sub-Four.

 

The full details for the hill are:

Group:  Pen y Ghent

Name:  Warrendale Knotts

OS 1:50,000 map:  98

Summit Height:  417.2m (LIDAR)

Summit Grid Reference:  SD 83674 64368 (LIDAR)

Col Height:  401.0m (LIDAR)

Col Grid Reference:  SD 83596 64470 (LIDAR)

Drop:  16.3m (LIDAR)

 

For the additions, deletions and reclassifications to The Fours – The 400m Hills of England reported on Mapping Mountains since the December 2013 publication of the 1^st edition of this list by Europeaklist please consult the following Change Registers:

 

The Fours

 

Sub-Fours

 

Myrddyn Phillips and Aled Williams (October 2025)