Cefn Wylfre (SO 145 510) – 490m Sub-Uchaf
addition
There has been an addition to the listing of Yr Uchafion instigated from analysis of
LIDAR data by Aled Williams. Yr Uchafion is the draft title for a
list of the Welsh 500m P15s that takes in all hills in Wales at or above 500m
in height that have a minimum drop of 15m, the list is a joint compilation
between Myrddyn Phillips and Aled Williams with the introduction to the list being
published on Mapping Mountains in November 2015.
Accompanying the main Yr
Uchafion list are three sub lists; 500m
Sub-Uchaf, 490m Sub-Uchaf and the
Double Sub-Uchaf categories, with the
addition of this hill affecting the 490m
Sub-Uchaf category, with the criteria for inclusion to this sub category
being all Welsh hills at or above 490m and below 500m in height that have a
minimum 15m of drop.
Prior to analysis of LIDAR data this hill was not
classified as its estimated drop was c 15m based on its 489m summit spot height
that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated
bwlch height of c 474m based on bwlch contouring between 470m – 480m.
The hill is situated in the Elfael group of hills
with its Cardinal Hill being Glascwm Hill (SO 169 525) and is placed in the
Region of Mid and West Wales (Region B, Sub-Region B1), with the small
communities of Glascwm towards the north north-east, Hundred House towards the
north-west and Cregrina towards the west north-west.
The hill is a part of designated open access land
and for those wishing to visit there are a number of tracks leading toward the
hill from the west and the south, and it can also be combined with its higher
neighbours if wanting a longer walk.
The name of the hill is Cefn Wylfre and its
addition to the 490m Sub-Uchaf
category is due to the analysis of LIDAR data by Aled. 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:
Cefn Wylfre
Summit Height: 490.1m
Summit Grid Reference:
SO 14585 51034
Bwlch Height: 474.9m
Bwlch Grid Reference:
SO 14819 51062
Drop: 15.2m
Therefore, the 490.1m LIDAR data produced for the
summit position at SO 14585 51034 and
the 474.9m LIDAR data produced for the bwlch position at SO
14819 51062 gives this hill 15.2m of drop which when coupled with its height is
sufficient for it to be classified as a 490m
Sub-Uchaf.
The full details for the hill are:
Cardinal Hill: Glascwm
Hill
Summit Height: 490.1m (LIDAR
data)
Name: Cefn Wylfre
OS 1:50,000 map: 148
Summit Grid Reference:
SO 14585 51034
Drop: 15.2m (LIDAR
data)
The overall total for Yr
Uchafion / The Welsh 500m P15s remains at 631 hills with the total for the 490m Sub-Uchaf category increasing by
one to 63 hills.
For the additions, reclassifications and deletions to Yr Uchafion / The Welsh 500m P15s
reported on Mapping Mountains please consult the following Change Registers:
Myrddyn Phillips and Aled Williams (October 2017)
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