Gwastad Meirionydd (SH 589 071) – 200m
Sub-Twmpau addition
There has been an addition to the 200m Twmpau due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:
200m Twmpau - Welsh hills at and above 200m and below 300m in height with 30m
minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau with the criteria for this sub category being all
Welsh hills at and above 200m and below 300m in height with 20m and more and
below 30m of drop, with the word Twmpau
being an acronym standing for thirty
welsh metre prominences and upward.
Prior to LIDAR analysis this hill was listed with 19m
of drop based on the 214m summit spot height that appears on the Ordnance
Survey 1:50,000 Landranger and 1:25,000 Explorer map and the bwlch spot height
of 195m that appears on the Ordnance Survey 1:25,000 Explorer map.
Extract from the Ordnance Survey 1:25,000 Explorer map |
The name of the hill is
Gwastad Meirionydd and it is adjoined to the Cadair Idris group of hills, which are situated in the south-western
part of North Wales (Region A, Sub-Region A3), and the hill is positioned between
the coast to its north-west and the Afon Dysynni to its south-east and has the
small communities of Llwyngwril to the north and Llanegryn to the south-east.
If wanting to visit the hill
permission to do so should be sought as it is not a part of designated open
access land, however the track to its west and north is a bridleway and is not
too far from the high point of the hill.
The addition of Gwastad Meirionydd
to 200m Sub-Twmpau status is due to
LIDAR analysis of the bwlch conducted by Myrddyn Phillips, with the summit of
the hill not covered by LIDAR. The LIDAR
(Light Detection & Ranging) technique produced highly accurate height data
that is now freely available for much of England and Wales.
The 2m DTM LIDAR analysis gives the hill the
following details:
Gwastad Meirionydd
Summit Height: 214m
Summit Grid Reference:
SH 589 071
Bwlch Height: 191.5m
Bwlch Grid Reference:
SH 59229 08003
Drop: 23m
LIDAR image of Gwastad Meirionydd |
Therefore, the 191.5m LIDAR analysis for the bwlch
position at SH 59229 08003 when coupled with the 214m summit
height gives this hill 23m of drop, which is sufficient for 200m Sub-Twmpau status.
The full details for the hill are:
Group: Cadair Idris
Name: Gwastad
Meirionydd
Summit Height: 214m
Summit Grid
Reference: SH 589 071
Bwlch
Height: 191.5m (LIDAR)
Bwlch Grid
Reference: SH 59229 08003 (LIDAR)
OS 1:50,000 map: 124
Drop: 23m
Myrddyn Phillips (May 2018)
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