Blaen yr Henbant (SO 254
217) - Double 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
that have a minimum drop of 15m, the list is a joint compilation with Aled
Williams, and details relating to this list were published on the Mapping Mountains
site 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 Double
Sub-Uchaf classification, with the criteria for inclusion to this sub
category being all Welsh hills at or above 490m and below 500m in height that
have 14m or more and below 15m of drop.
Prior to analysis of LIDAR data the hill was catalogued
with 12m of drop based on the 498m summit spot height that appears on the
Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps and the 486m
bwlch spot height that appears on the Ordnance Survey enlarged mapping hosted
on the Geograph website.
The hill is situated in the Mynyddoedd Duon (Black Mountains) group of hills with its Cardinal
Hill being Waun Fach (SO 215 299) and
is placed in the Region of South Wales (Region C, Sub-Region C3), and is
positioned between the town of Crucywel
(Crickhowell) to the south-west and the small community of Forest Coal Pit to
the east south-east.
The hill can be accessed via a bridleway from its
south-west that forms a part of the Beacons Way, or from public footpaths
towards the south and north-east.
However, the hill is positioned at the end of one of this hill ranges
extended ridges and a two car walk taking in the full length of this ridge ending
on the summit of Blaen yr Henbant is
highly recommended.
The name of the hill is Blaen yr Henbant and its inclusion as a Double Sub-Uchaf 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:
Blaen yr Henbant
Summit Height: 497.8m
(converted to OSGM15)
Summit Grid Reference:
SO 25412 21736
Bwlch Height: 483.0m
(converted to OSGM15)
Bwlch Grid Reference:
SO 25537 22004
Drop: 14.8m
Therefore, the 497.8m (converted to OSGM15) LIDAR
data produced for the summit position at SO 25412 21736 and the 483.0m (converted to OSGM15) LIDAR data
produced for the bwlch position at SO 25537 22004 gives
this hill 14.8m of drop and when combined with its summit height is sufficient
for the hill to be included as a Double Sub-Uchaf.
The full details for the hill are:
Cardinal Hill: Waun
Fach
Summit Height: 497.8m
(converted to OSGM15) (LIDAR data)
Name: Blaen yr Henbant
OS 1:50,000 map: 161
Summit Grid Reference:
SO 25412 21736
Drop: 14.8m (converted
to OSGM15) (LIDAR data)
The overall total for Yr
Uchafion / The Welsh 500m P15s remains at 631 hills with the total for the Double Sub-Uchaf category now being 6.
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 (April 2017)
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