Mynydd yr Ychen (SN 768 794) – 400m Sub-Pedwar deletion
THIS HILL HAS SUBSEQUENTLY BEEN RE-INSTATED TO 400m SUB-PEDWAR STATUS
THIS HILL HAS SUBSEQUENTLY BEEN RE-INSTATED TO 400m SUB-PEDWAR STATUS
There has been a deletion to the listing of Y Pedwarau due to analysis of LIDAR data
by Aled Williams. Y Pedwarau is the title for the list of 400m hills of Wales and
takes in all Welsh hills at or above 400m and below 500m in height that have a
minimum 30m of drop, the list is a joint compilation between Myrddyn Phillips
and Aled Williams and it commenced publication on Mapping Mountains on the
30.01.17.
Accompanying the main Y
Pedwarau list are five categories of sub hills, with this hill being deleted
from 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 c 20m of drop based on the 459m summit spot height that appears on the
Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 439m
based on interpolation of bwlch contouring between 430m – 440m.
The hill is situated in the Elenydd range with its
Cardinal Hill being Draws Drum (SN 790 811) and is placed in the Region of Mid and West Wales (Region B,
Sub-Region B2), and is positioned with the small community of Pontarfynach (Devil’s Bridge) to the south-west
and Ponterwyd to the north-west.
The hill is a part of designated open access land
and can be accessed directly from the A 4120 and B 4343 roads which are to the
west of the summit, public footpaths also give access to the open access land
and originate towards the north-west and the west respectively, otherwise if
wanting to visit the hill a longer route can be devised that takes in a number
of adjacent hills.
The name the hill is listed by is Mynydd yr Ychen 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:
Mynydd yr Ychen
Summit Height: 459.9m (converted to OSGM15)
Summit Grid Reference:
SN 76846 79457
Bwlch Height: 439.9m (converted to OSGM15)
Bwlch Grid Reference: SN 77051 79549
Drop: 19.98m
Therefore, the 459.9m LIDAR data produced for the summit
position at SN 76846 79457 and the 439.9m LIDAR data
produced for the bwlch position at SN 77051 79549 gives
this hill 19.98m of drop which is insufficient for its continued inclusion as a 400m Sub-Pedwar.
The full details for the hill are:
Cardinal Hill: Draws
Drum
Summit Height: 459.9m
(converted to OSGM15, LIDAR data)
Name: Mynydd yr Ychen
OS 1:50,000 map: 135,
147
Summit Grid Reference:
SN 76846 79457
Drop: 19.98m (converted
to OSGM15, LIDAR data)
The total for Y
Pedwarau remains at 442 hills with nine additions, and fourteen
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 219 with 25 hills being added and 19 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 (June 2017)
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