Curnau Mawr (SN 751 750) – Sub-Trichant addition
There has been an addition to the listing of Y Trichant due to analysis of LIDAR data
by Aled Williams and subsequently confirmed via a survey with the Trimble GeoXH
6000. Y Trichant is the title for the hills in the 300m height band of
the Twmpau (thirty welsh metre
prominences and upward) and takes in all Welsh hills at or above 300m and below
400m in height that have a minimum 30m of drop, with the introduction to the
re-naming of this list appearing on Mapping Mountains on the 13th
May 2017.
The hill did not appear in the sub category that accompanied
the original Welsh P30 lists when published on Geoff Crowder’s v-g.me website,
this sub category has now been standardised and named the Sub-Trichant and comprises all Welsh hills at or above 300m and
below 400m in height with 20m or more and below 30m of drop.
Prior to analysis of LIDAR data the hill was not
classified but it was catalogued with c 16m of drop based on an estimated c
390m summit height and an estimated c 374m bwlch height, the latter height
based on interpolation of bwlch contouring between 370m – 380m.
The hill is a part of the Elenydd
range with its Cardinal Hill being Pen
y Garn (SN 798 771) and is placed in the Region of Mid and West Wales
(Region B, Sub-Region B2). The hill is
situated with the B 4574 to its north and the B 4343 to its west and is
positioned between the small communities of Pontarfynach
(Devil’s Bridge) to its north-west and Cwmystwyth
to its east south-east.
For those wishing to visit the summit the whole upper section
of the hill is a part of designated open access land, and this has immediate
access from the B 4343 to the west or from a public footpath from the same road
that intersects with the open access lane.
The name of the hill is Curnau Mawr and its addition to Sub-Trichant
status is due to the analysis of
LIDAR data by Aled Williams. LIDAR (Light Detection
& Ranging) is highly accurate height data that is now freely available for
much of England and Wales.
Aled’s analysis of LIDAR data gives the hill the
following details:
Curnau Mawr
Summit Height: 391.4m
Summit Grid Reference:
SN 75155 75007
Bwlch Height: 369.8m
Bwlch Grid Reference:
SN 75343 74906
Drop: 21.6m
Therefore, the 391.4m LIDAR data produced for the summit
position at SN 75155 75007 and the 369.8m LIDAR data
produced for the bwlch position at SN 75343 74906 gives
this hill 21.6m of drop which is sufficient for its inclusion as a Sub-Trichant,
with the details from the Trimble GeoXH 6000 survey being 391.4m (converted to
OSGM15) summit at SN 75154 75006 and 369.8m (converted to OSGM15) bwlch at SN
75342 24906, giving this hill 21.6m of drop.
The full details for the hill are:
Cardinal Hill: Pen y
Garn
Summit Height: 391.4m
(converted to OSGM15, Trimble GeoXH 6000)
Name: Curnau Mawr
OS 1:50,000 map: 135,
147
Summit Grid Reference:
SN 75154 75006
Drop: 21.6m
Curnau Mawr (SN 751 750) confirmed as a Sub-Trichant |
My thanks to Aled Williams for sending the details of this hill to me
Myrddyn Phillips (July 2017)