Mapping Mountains – Significant Height Revisions – The Fours – The 400m Hills of England

Addlebrough (SD 947 878) 

There has been a Significant Height Revision 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 Addlebrough (SD 947 878)

The criteria for the list this height revision affects 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 Addlebrough, and it is adjoined to the Whernside group of hills, which are situated in the central Pennines, and it is positioned with the A684 road to its north, a minor road to its west and the B6160 road to its south-east, and has the village of Bainbridge towards the north-west.

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 945 881 based on where the contemporary Ordnance Survey 1:25,000 Explorer map indicated an uppermost 480m ring contour to be situated. 

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

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 listed with an estimated c 481m summit height, based on interpolation of what was indicated as its highest 480m contour ring that appears on the Ordnance Survey 1:25,000 Explorer map, with its listed summit position being relocated to SD 947 878.

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 Addlebrough (SD 947 878)

LIDAR analysis gives the highest ground on this hill as 478.9m positioned at SD 94744 87872, and this comes within the parameters of the Significant Height Revisions used within this page heading, these parameters are:

The term Significant Height Revisions applies to any listed hill whose interpolated height and Ordnance Survey or Harvey map summit spot height has a 2m or more discrepancy when compared to the survey result produced by the Trimble GeoXH 6000 or analysis of data produced via LIDAR, also included are hills whose summit map data is missing an uppermost ring contour when compared to the data produced by the Trimble or by LIDAR analysis.

Therefore, the new listed summit height of this hill is 478.9m and this was derived from LIDAR analysis, 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 2.1m lower than the previously estimated c 481m summit height, which was based on interpolation of what was indicated as its highest 480m contour ring, which LIDAR indicates is 470m in height. 

 

The full details for the hill are:

Group:  Whernside

Name:  Addlebrough

OS 1:50,000 map:  98

Summit Height (New Height):  478.9m (LIDAR)

Summit Grid Reference:  SD 94744 87872 (LIDAR)

Col Height:  386.8m (LIDAR)

Col Grid Reference:  SD 94822 87149 (LIDAR)

Drop:  92.1m (LIDAR)

 

Myrddyn Phillips and Aled Williams (May 2023)