Mapping Mountains – Hill Reclassifications – Welsh Highlands – Uchafion Cymru

Pen y Castell (SH 724 688) – Welsh Highland Sub addition 

There has been an addition to the listing of the Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill derived a combination of an optical level survey conducted by Graham Jackson and Myrddyn Phillips, a Leica RX1250 survey conducted by Alan Dawson and LIDAR analysis conducted by Aled Williams. 

LIDAR image of Pen y Castell (SH 724 688)

The criteria for the list that this addition applies to are:

Welsh Highlands – Uchafion Cymru – Welsh hills at or above 500m in height with 15m minimum drop, with an accompanying sub list entitled the Welsh Highland Subs, the criteria for which is all Welsh hills at or above 500m in height with 10m or more and below 15m of drop.  This list is authored by Myrddyn Phillips and Aled Williams with the Introduction to the list published on Mapping Mountains in November 2015 and the latest update relating to the list published on Mapping Mountains in January 2023.

Welsh Highlands - Uchafion Cymru by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Pen y Castell and it is adjoined to the Carnedd Llywelyn group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned with a minor road to its east north-east, and the B5106 road and the A470 road farther to its east, and has the village of Llanbedrycennin towards the east.

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

The summit of this hill was surveyed by optical level from its near higher summit on the 9^th April 2010 by Graham Jackson and Myrddyn Phillips and determined to be 2.43m lower.  The higher summit positioned at SH 72187 68880 was subsequently surveyed by Alan Dawson using a Leica RX1250 on the 14^th June 2017, resulting in a 623.516m summit height.  Therefore, the lower summit relative to the higher is 621.086m in height.

However, it was not until LIDAR became available that the bwlch 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 Welsh Highland Sub status is due to an optical level survey, a Leica RX1250 survey and LIDAR analysis, resulting in a 621.1m summit height and a 611.0m bwlch height, with these values giving this hill 10.0m of drop, which is sufficient for it to be classified as a Welsh Highland Sub. 

                                                                                                                                      

The full details for the hill are: 

Group:  Carnedd Llywelyn

Name:  Pen y Castell

OS 1:50,000 map:  115

Summit Height:  621.1m (relative to optical level survey [2.43m lower] from 623.5m higher summit)

Summit Grid Reference:  SH 72434 68874 (LIDAR)

Bwlch Height:  611.0m (LIDAR)

Bwlch Grid Reference:  SH 72374 68895 (LIDAR)   

Drop:  10.0m (relative to optical level survey [2.43m lower] from 623.5m higher summit and LIDAR bwlch) 

 

For the additions, deletions and reclassifications to the Welsh Highlands – Uchafion Cymru reported on Mapping Mountains please consult the following Change Registers:

 

Welsh Highland P15s

 

Welsh Highland Subs

 

Aled Williams and Myrddyn Phillips (June 2023)