Coed y Bwnydd (SO 366 069) – Lesser Dominant reclassified to
Dominant
There has been a reclassification to the list of
the Y Trechol – The Dominant Hills of
Wales, with the summit height, bwlch height and their locations, the drop,
dominance and status of the hill confirmed by LIDAR analysis conducted by
Myrddyn Phillips.
LIDAR image of Coed y Bwnydd (SO 366 069) |
The criteria for the list that this reclassification
applies to are:
Y Trechol - The Dominant Hills of
Wales - Welsh P30 hills whose prominence
equal or exceed half that of their absolute height. With the
criteria for Lesser Dominant status being those additional Welsh P30 hills whose
prominence is between one third and half that of their absolute height, with
the Introduction to the Mapping Mountains publication of this list appearing on the 3rd December 2015, and the list is now available in its entirety on Mapping Mountains in Google Doc format.
The name the hill is listed by is
Coed y Bwnydd and it is adjoined to the Mynyddoedd Duon group of hills which
are situated in the eastern part of South Wales (Region C, Sub-Region C3), and
it is positioned with the Afon Wysg (River Usk) and the B4598 road to its west,
the A40 road to its north and the A449 road to its east, and has the village of
Raglan towards the east north-east and the town of Brynbuga (Usk) towards the
south south-east.
When the original 100m height band of Welsh P30
hills were published on Geoff Crowder’s v-g.me website this hill was included
in the main P30 list under the name of Clytha Hill and listed with a 196m
summit height, based on the spot height that appears on the Ordnance Survey
1:25,000 Explorer map at SO 368 069.
Extract from the Ordnance Survey 1:25,000 Explorer map |
When the P30 lists were 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 68m of drop based on the
196m summit height and an estimated bwlch height of c 128m. These details were transferred to the
Dominants list when first compiled, with these values giving this hill 34.69%
dominance.
The details for this hill were re-assessed when
the Ordnance Survey Vector Map Local hosted on the Geograph website and which
is entitled the Interactive Coverage Map became available online. This mapping had many spot heights not on
other publicly available Ordnance Survey maps and gives a second 196m spot
height on the summit area of this hill and positioned at SO 367 069. This additional 196m spot height also appears
on Ordnance Survey data available on the Magic Maps website.
Extract from the Magic Maps website |
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 summit image of Coed y Bwnydd |
LIDAR bwlch image of Coed y Bwnydd |
Therefore, the reclassification of this hill from Lesser
Dominant status is due to LIDAR analysis, resulting in a 201.0m summit height
and a 59.4m bwlch height, with these values giving this hill 141.6m of drop and
70.45% dominance. With the 201.0m summit
height taken to the remains of an embankment which forms a part of an ancient
hill fort and the 59.4m bwlch height taken to a road cutting, and as ancient
summit structures deemed permanent in nature and the depth of road and rail
cuttings qualify under the criteria used within this list the dominance is sufficient
for this hill to be reclassified to Dominant status.
The full details for the
hill are:
Group: Mynyddoedd Duon
Name: Coed y Bwnydd
OS 1:50,000 map: 161
Summit Grid
Reference: SO 36613 06921 (LIDAR)
Summit Height: 201.0m (LIDAR)
Bwlch Grid
Reference: SO 39307 08899 (LIDAR)
Drop Summit to Bwlch: 141.6m (LIDAR)
Drop Bwlch to ODN: 59.4m (LIDAR)
Dominance: 70.45% (LIDAR)
Myrddyn Phillips (February
2020)
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