Mapping Mountains – Hill Reclassifications – Welsh Highlands – Uchafion Cymru

Clo Cadno (SO 118 162) – Welsh Highland P15 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 from LIDAR analysis conducted by Aled Williams.

LIDAR image of Clo Cadno (SO 118 162)

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

The Welsh Highlands – Uchafion Cymru – This is the revised draft title for the Welsh 500m P15s list that takes in all hills in Wales at or above 500m in height with 15m minimum drop.  The list is co-authored by Myrddyn Phillips and Aled Williams with the Introduction to the list being published on Mapping Mountains in November 2015 and an update relating to the list appearing on Mapping Mountains on the 19th June 2019.

The name the hill is listed by is Clo Cadno and it is adjoined to the Cymoedd Gwent group of hills, which are situated in the eastern part of South Wales (Region C, Sub-Region C2), and is positioned with minor roads to its north-west and south-west and the B4560 road to its east, and has the village of Llangynidr towards the north-east and the small community of Trefil towards the south.

During the compilation of the original list of Welsh 500m P15s that later became known as Yr Uchafion and latterly as the Welsh Highlands – Uchafion Cymru, this hill was not included in the main P15 list as Ordnance Survey 1:25,000 Explorer maps only give an uppermost 520m ring contour with bwlch contouring between 510m – 520m.

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

The details for this hill were re-examined via mapping on the OS Maps website.  This is the replacement for OS Get-a-map and has contours at 5m intervals which are proving consistently more accurate compared to the 5m contours that sometimes appear on Ordnance Survey 1:25,000 Explorer maps and the online Vector Map Local hosted on the Geograph website.  As OS Maps data suggested that this hill had a minimum of 15m of drop it prompted scrutiny using LIDAR.

Extract from the OS Maps website

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 Clo Cadno to Welsh Highland P15 status is due to LIDAR analysis, resulting in a 530.3m summit height and a 513.6m bwlch height, with these values giving this hill 16.7m of drop which is sufficient for it to be classified as a Welsh Highland P15.

The full details for the hill are:

Group:  Cymoedd Gwent

Name:  Clo Cadno

OS 1:50,000 map:  161

Summit Height:  530.3m (LIDAR)

Summit Grid Reference:  SO 11849 16247 (LIDAR)

Bwlch Height:  513.6m (LIDAR)

Bwlch Grid Reference:  SO 12197 15992 (LIDAR)

   

Drop:  16.7m (LIDAR) 

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

The Welsh 500m P15s (Yr Uchafion)

The Welsh 500m P15s (Yr Uchafion) – 500m Subs

The Welsh 500m P15s (Yr Uchafion) – 490m Subs

The Welsh 500m P15s (Yr Uchafion) – Double Subs

Aled Williams and Myrddyn Phillips (January 2020)