Pt. 458.5m (SN 982 116) - 400m Sub-Pedwar deletion
There has been an alteration to the listing of Y Pedwarau due to analysis of LIDAR data
by Aled Williams. Y Pedwarau is the title for the co-authored listing of the 400m
hills of Wales, with the criteria for this list being all Welsh hills at or
above 400m and below 500m in height with a minimum 30m of drop.
Accompanying the main Y
Pedwarau list are five categories of sub hills, with this alteration
affecting the 400m Sub-Pedwar
category. The criteria for 400m Sub-Pedwar qualification is all
Welsh hills at or above 400m and below 500m in height with 20m or more and
below 30m of drop.
Prior to analysis of LIDAR data the hill was listed
with 20m of drop based on the 458m summit spot height that appears on the
Ordnance Survey 1:25,000 Explorer map and the 438m bwlch spot height that appears
on the Ordnance Survey enlarged mapping hosted on the Geograph website.
The hill is situated in the Fforest Fawr group of hills with its Cardinal Hill being Fan Fawr (SN 969 193) and is placed in
the Region of South Wales (Region C, Sub-Region C2). The hill is positioned above the small
communities of Penderyn to its
south-west and Llwyn Onn to its east.
The hill is situated on open access land and can
be easily accessed from either its north north-west from the A 4059 road and
also taking in the 485m map heighted Pedwar
of Cadair Fawr (SN 977 123), or
it can be accessed from its south-east from the convenience of a narrow minor
road that reaches over 400m in height.
As the authors do not know an individual name for
the hill either from local and / or historical research we are following the
point (Pt. 458.5m) notation and its deletion from 400m Sub-Pedwar 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:
Pt.
458.5m
Summit
Height: 458.5m
Summit
Grid Reference: SN 98267 11645
Bwlch
Height: 438.9m
Bwlch
Grid Reference: SN 98245 11829
Drop: 19.6m
Therefore, the 458.5m LIDAR data produced for the
summit position at SN 98267 11645 and
the 438.9m LIDAR data produced for the bwlch position at SN
98245 11829 gives this hill 19.6m of drop which is insufficient for its retention
as a 400m Sub-Pedwar.
The full details for the hill are:
Cardinal Hill: Fan
Fawr
Summit Height: 458.5m
(LIDAR data)
Name: Pt. 458.5m
OS 1:50,000 map: 160
Summit Grid Reference: SN 98267 11645
Drop: 19.6m (LIDAR
data)
The overall total for Y
Pedwarau remains at 445 hills with eight additions, and ten
reclassifications to 400m Sub-Pedwar
status since publication of the list by Europeaklist in May 2013.
The overall total for the 400m
Sub-Pedwarau is now 217 with 18 hills being added and 14 hills being taken
out of this category since publication of the list by Europeaklist in May 2013.
The list of Pedwar
hills is available from the Haroldstreet website (January 2014) with all
subsequent changes detailed on the Mapping Mountains site, with the list also
having commenced publication on Mapping Mountains on the 30.01.17.
For the additions, reclassifications and deletions to Y Pedwarau reported on Mapping Mountains
since the May 2013 publication of the list by Europeaklist please consult the
following Change Registers:
Myrddyn Phillips and Aled Williams (April 2017)
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