Blaen y Clawdd Du (SN 878
752) - Uchaf addition
There has been a new entry 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. Details relating to this list
were published on the Mapping Mountains site in November 2015.
The listing of Yr
Uchafion includes three sub lists; the 500m
Sub-Uchaf, 490m Sub-Uchaf and the
Double Sub-Uchaf category. The classification of this hill is from
unclassified to Uchaf, as the hill
was previously catalogued with insufficient drop even to attain 500m Sub-Uchaf status.
The hill is situated in the Elenydd group of hills 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). The hill is situated with the small community
of Llangurig to the north-east and is
positioned between the stream valleys of the Afon Elan to the south and the Nant
y Trafel Gwyn which flows into the Nant
y Dernol to the east.
The hill can be accessed from a forestry road to
its north, although this may require a bit of tree bashing to reach its high
point unless the track is left for open hillside at the northerly connecting bwlch,
or it can be accessed from the south-west where a narrow mountain road gives
the opportunity of starting the ascent from approximately 390m high.
The hill was previously catalogued with 13m of
drop and therefore thought of as being unclassified, this value was based on detail
from Ordnance Survey maps, with the 1:50,000 Landranger, the 1:25,000 Explorer
and the enlarged map hosted on the Geograph website all giving a summit spot
height of 517m, with the latter map also giving a bwlch spot height of 504m.
The name of the hill is Blaen y Clawdd Du and its classification as an Uchaf is due to 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 y Clawdd Du
Summit Height: 516.8m
Summit Grid Reference:
SN 87845 75282
Bwlch Height: 501.2m
Bwlch Grid Reference:
SN 87916 75115
Drop: 15.6m
Therefore, the 516.8m LIDAR data produced for the
summit position at SN 87845 75282 and
the 501.2m LIDAR data produced for the bwlch position at SN 87916
75115 gives this hill 15.6m of drop which is sufficient for it to be included as an Uchaf as its drop value is
more than the minimum of 15m required.
The full details for the hill are:
Cardinal Hill: Draws
Drum
Summit Height: 516.8m
(LIDAR data)
Name: Blaen y Clawdd
Du
OS 1:50,000 map: 135,
136, 147
Summit Grid Reference:
SN 87845 75282
Drop: 15.6m (LIDAR
data)
This now brings the overall total for Yr Uchafion / The Welsh 500m P15s to 629 hills with the overall
total for the 500m Sub-Uchaf category
remaining at 26.
The additions, reclassifications and deletions to Yr Uchafion / The Welsh 500m P15s
reported on Mapping Mountains are as follows:
UCHAF ADDITIONS
Blaen y Clawdd Du (LIDAR data) (SN 878 752) added as an Uchaf
with 15.6m of drop
UCHAF RECLASSIFICATIONS
UCHAF DELETIONS
Myrddyn Phillips and Aled Williams (February 2017)
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