Mapping Mountains – Hill Reclassifications – Humps

Llandegley Rocks (SO 131 618) – Subhump addition

This is the twenty second in a series of Hill Reclassification posts that detail hills whose status has been altered in the listing of the Humps (HUndred Metre Prominences) through map study and / or surveys that I have conducted.

Llandegley Rocks (SO 131 618 [as listed in the Humps])

This and forthcoming posts are retrospective as many of these hill reclassifications were initiated from studying the Ordnance Survey enlarged mapping that is hosted on the Geograph website and the Ordnance Survey Six-Inch base maps available online, and for the reclassifications that affected the Humps the details relating to this hill were sent to Mark Jackson via email on the 11.05.14.

The listing of Humps was published in book format by Lulu in 2009 and entitled More Relative Hills of Britain, its author; Mark Jackson gives credit to a number of people who contributed toward the formation of this list, these include; Eric Yeaman, Alan Dawson, Clem Clements, Rob Woodall, Bernie Hughes, Pete Ridges and others.  When the list was published in book format there were 2987 Humps listed with their criteria being any British hill that has 100m or more of drop, accompanying the main list is a sub category entitled Subhumps, with the criteria being any British hill that has 90m or more and below 100m of drop.

More Relative Hills of Britain by Mark Jackson

The details for the reclassification appear below:

There has been a reclassification to the listing of the Humps (HUndred Metre Prominences) due to consulting the Ordnance Survey 1:2,500 base map available online, with these details being sent to Mark Jackson on 11.05.14.

Prior to this notification Mark Jackson had listed this hill with c 89m of drop based on the 436m summit height given to a triangulation pillar on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated bwlch height of c 347m based on bwlch contouring at 10m intervals.  However, the Ordnance Survey 1:50,000 Landranger map has a 345m bwlch spot height that derives from the 1131ft (344.7m) levelled height that appears on the Ordnance Survey 1:2,500 map, with these values giving the hill 91m of drop which is sufficient for it to be classified as a Subhump.  This hill has subsequently been analysed with LIDAR data by Aled Williams and surveyed with the Trimble GeoXH 6000, with the latter resulting in a 436.3m summit at SO 13202 61752 and a 345.5m bwlch at SO 11361 59616, with these values giving this hill 90.8m of drop.

Extract from the Ordnance Survey 1:2,500 map showing the 1131ft imperial height on the area of this hill's bwlch

Extract from the Ordnance Survey 1:50,000 Landranger map showing the 345m spot height which was derived from the old 1131ft imperial height

Gathering data at the critical bwlch of Llandegley Rocks

The hill is adjoined to the Elfael range of hills and is situated overlooking the A 44 road which is to its east and north, and the Afon Ieithon (River Ithon) which is to its west, with the small community of Llandegley towards the north of the hill.

The addition of this hill to Subhump status was accepted by Mark Jackson and its new classification augmented in to the listing of the Humps on the 11.05.14.

The full details for the hill are:

Name:  Llandegley Rocks (as listed in the Humps)

Summit Height:  436m (as listed in the Humps) 

OS 1:50,000 map:  148

OS 1:25,000 map:  200

Summit Grid Reference:  SO 13148 61808 (as listed in the Humps)

Drop:  91m (as listed in the Humps)

Myrddyn Phillips (October 2017)