Banc y Llyn (SN 804 652) - 400m Sub-Pedwar addition
There is a new hill joining the ranks of 400m Sub-Pedwarau by analysis of LIDAR data by Aled Williams. The 400m
Sub-Pedwarau is one of five categories of sub hills that accompany the
main Y Pedwarau list, with the
criteria for 400m Sub-Pedwar status
being all Welsh hills at or above 400m and below 500m in height with 20m or
more and below 30m of drop.
The hill is situated in the Elenydd group of hills
which is one of the wildest hill ranges in Wales, with its Cardinal Hill being Drygarn
Fawr (SN 862 584) and is placed in the Region of Mid and West Wales (B-2). The hill is positioned between the small
communities of Pontrhydfendigaid towards the west and the Elan Village towards
the east, and is situated above Llyn Gynon which is to its south-west.
Whatever way one approaches, it is relatively
remote for a Welsh hill with access from the west probably being the easiest
with a track leaving the paved road that heads east from the ruins of Strata
Florida Abbey toward the old farm house of Garreglwyd, from here the going will
be rough with the prospect of it also being wet as whatever way one approaches
the hill at least one stream has to be negotiated, with the hill positioned with
wetlands to its immediate north and streams feeding toward Llyn Gynon to its
west and east and the lake toward the south.
The name of the hill is Banc y Llyn and prior to the
analysis of LIDAR data and its subsequent listing as a 400m Sub-Pedwar it has been listed as a Pellennig hill (Y Pellennig –
the Remotest Hills of Wales [Mapping Mountains Publications July 2016])
with c 19m of drop based on its 474m summit spot height on the Ordnance Survey
1:25,000 Explorer map and an estimated bwlch height of c 455m based on bwlch
contouring between 450m – 460m.
As Aled was analysing other hills in the vicinity
against LIDAR data, he did likewise with Banc y Llyn. 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:
Banc y Llyn
Summit Height: 473.3m
Summit Grid Reference: SN 80496 65235
Bwlch Height: 452.0m
Summit Grid Reference: SN 80496 65235
Bwlch Height: 452.0m
Bwlch Grid Reference: SN 80404 65691
Drop: 21.7m
Therefore, the 473.7m LIDAR data produced for the summit
position at SN 80496 65235 and the 452.0m LIDAR data
produced for the bwlch position at SN 80404 65691 is sufficient for this hill
to be classified as a 400m Sub-Pedwar
with 21.7m of drop, and therefore Banc y Llyn is included in the listing of 400m Sub-Pedwar hills and the list of the Y Pedwarau will be updated
accordingly. The list of Pedwar hills is available from the
Haroldstreet website (January 2014) with all subsequent changes available via
the Mapping Mountains site.
The full details for the hill are:
Cardinal Hill: Drygarn
Fawr
Summit Height: 473.7m
(LIDAR data) 5
Name: Banc y Llyn
OS 1:50,000 map: 135,
136, 147
Summit Grid Reference:
SN 80496 65235
Drop: 21.7m (LIDAR data)
The list of additions, reclassifications and deletions from
the 400m Sub-Pedwar list since the 1st
edition of the Y Pedwarau was published
by Europeaklist are as follows:
SUB-PEDWAR ADDITIONS
Banc y Llyn (LIDAR data) (SN 804 652) 21.7m drop
Pt. 422.3m (converted to OSGM15) (SO 073 822) Pedwar reclassified to 400m Sub-Pedwar with 29.0m drop
Pt. 407.7m (converted to OSGM15) (SO 180 692) Pedwar reclassified to 400m Sub-Pedwar with 28.3m drop
SUB-PEDWAR RECLASSIFICATIONS
Pt. 499.5m (converted to OSGM15) (SH 665 310) 400m Sub-Pedwar reclassified to Pedwar with 30.3m drop
SUB-PEDWAR DELETIONS
Myrddyn Phillips and Aled Williams (February 2017)
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