Esgair Wen (SN 807 664) – 400m Sub-Pedwar reclassified to
Pedwar
There has been a reclassification to the listing
of the Y Pedwarau – The 400m Hills of
Wales, with the summit height, bwlch height and their locations, the drop
and status of the hill derived from LIDAR analysis conducted by Aled Williams.
%20-%20LIDAR%20hill%202.jpg) |
| LIDAR image of Esgair Wen (SN 807 664) |
The criteria for the list that this
reclassification applies to are:
 |
| Y Pedwarau - The 400m Hills of Wales by Myrddyn Phillips and Aled Williams |
The name the hill is listed by is Esgair Wen and it
is adjoined to the Drygarn Fawr group of hills, which are situated in the northern part of South
Wales (Region B, Sub-Region B1), and
it is positioned with minor roads to its north-west, west south-west and east south-east, and has the village of Pontrhydfendigaid
towards the west.
After the sub list was standardised, and interpolated
heights and drop values also included the details for this hill were
re-evaluated and it was listed with an estimated c 30m of drop, based on the 496m
summit spot height that appeared on the contemporary Ordnance Survey 1:25,000
Explorer map, and an estimated c 466m bwlch height, based on interpolation of
10m contouring between 460m – 470m.
%20-%201%2025000.jpg) |
| Extract from the Ordnance Survey 1:25,000 Explorer map |
Since the original publication of the Welsh P30
lists on Geoff Crowder’s v-g.me website there have been a number of maps made
available online. Some of these are
historic such as the series of Six-Inch maps on the National Library of
Scotland website. Whilst others were digitally
updated such as the Ordnance Survey Vector Map Local that was hosted on the
Geograph website and which was entitled the Interactive Coverage Map, whilst
others are current and digitally updated such as the interactive mapping on the
Magic Maps and WalkLakes websites.
The details for this hill were re-assessed when
the Ordnance Survey Vector Map Local hosted on the Geograph website and which
was entitled the Interactive Coverage Map became available online. This mapping had many spot heights not on
other publicly available Ordnance Survey maps and for this hill it had a 465m bwlch
spot height, and when coupled with its 496m summit spot height these values
gave this hill 31m of drop, and these are the values given this hill when the 1st
edition of the Y Pedwarau was published
by Europeaklist in May 2013.
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.
The details for this hill were analysed using what
is now the archived Welsh LIDAR, resulting in a 494.6m summit height and a
464.7m bwlch height, with these values giving this hill 29.9m of drop and
therefore it was reclassified to 400m Sub-Pedwar status.
However, new Welsh LIDAR has now been used to
analyse the details for this hill, resulting in a 494.8m summit height and a 464.8m
bwlch height, with these values giving this hill 30.0m of drop, which is sufficient
for it to be reinstated to Pedwar status.
The full details for the hill are:
Group: Drygarn Fawr
Name: Esgair Wen
OS 1:50,000 map: 135,
136, 147
Summit Height: 494.8m (LIDAR)
Summit Grid
Reference: SN 80767 66474 (LIDAR)
Bwlch Height: 464.8m (LIDAR)
Bwlch Grid
Reference: SN 80123 66302 (LIDAR)
Drop: 30.0m (LIDAR)
For the additions, reclassifications and deletions to Y Pedwarau – The 400m Hills of Wales reported
on Mapping Mountains since the May 2013 publication of the list by Europeaklist
please consult the following Change Registers:
Y Pedwarau
Y Pedwarau – 400m Sub-Pedwarau
Y Pedwarau – 390m Sub-Pedwarau
Y Pedwarau – 390m Double Sub-Pedwarau
Myrddyn Phillips and Aled Williams (September 2023)
%20-%20LIDAR%20hill%202.jpg)
%20-%201%2025000.jpg)
