Pt. 522.2m (SJ 136 363) – 500m Sub-Uchaf
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 confirmed by 1m DSM LIDAR
analysis conducted by Aled Williams.
 |
| LIDAR image of Pt. 522.2m (SJ 136 363) |
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. Accompanying the main list are three sub
lists, these are; 500m Sub-Uchaf, 490m Sub-Uchaf and the Double Sub category,
with this hill being added as a 500m Sub-Uchaf.
The criteria for which are all Welsh hills at or above 500m in height
with 14m or more and below 15m of 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.
For now, the hill is being
listed by the point (Pt. 522.2m) notation, and it is adjoined to the Y Berwyn
group of hills, which are situated in the
south-eastern part of North Wales (Region A, Sub-Region A4), and it is positioned with the A5 road to its north, the
B4401 road to its west and the B4500 road to east, and has the town of
Llangollen towards the north-east.
This hill was included as a P14 Sub in the
original list of Welsh 500m P15s that later became known as Yr Uchafion and latterly as The Welsh Highlands – Uchafion Cymru, as
with a 522m summit spot height and a 508m bwlch spot height that appear on the
Ordnance Survey 1:25,000 Explorer map, these values gave this hill 14m of drop.
 |
| 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.
 |
| LIDAR bwlch image of Pt. 522.2m (SJ 136 363) |
The hill was subsequently deleted from 500m
Sub-Uchaf status based on DTM LIDAR analysis conducted by Aled Williams
resulting in a 522.0m summit height and a 508.2m bwlch height, with these
values giving this hill 13.8m of drop.
The details of this hill have now been re-assessed
using the 1m DSM LIDAR model by Aled Williams resulting in a 522.2m summit
height and a 508.2m bwlch height, with these values giving this hill 14.0m of
drop, which is sufficient for it to be re-instated to 500m Sub-Uchaf status.
The full details for the hill are:
Group: Y Berwyn
Name: Pt. 522.2m
OS 1:50,000 map: 125
Summit Height: 522.2m
(LIDAR)
Summit Grid Reference:
SJ 13614 36370 (LIDAR)
Bwlch Height: 508.2m (LIDAR)
Bwlch Grid Reference:
SJ 13888 36062 (LIDAR)
Drop: 14.0m (LIDAR)
For the additions, deletions and reclassifications to The Welsh Highlands – Uchafion Cymru
reported on Mapping Mountains please consult the following Change Registers:
Aled Williams and Myrddyn Phillips (August 2020)
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