Allt y Genlli (SN 985 950) – 390m Sub-Pedwar reinstated to 390m
Double Sub-Pedwar
There has been a reclassification to the listing of Y Pedwarau due to a survey with a Leica
GS15 conducted by John Barnard, Chris Crocker and Graham Jackson. 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
reclassified from a 390m Sub-Pedwar to
a 390m Double Sub-Pedwar. The criteria for 390m Sub-Pedwar status being all Welsh hills at or above 390m and
below 400m in height that have 30m minimum drop, whilst the criteria for 390m Double Sub-Pedwar status being all Welsh hills at or above 390m and below 400m
in height with 20m or more and below 30m of drop.
The name of the hill is Allt y Genlli and prior to
the survey with the Leica GS15 the hill was listed with 73.2m of drop, based on
a 398.9m summit and 325.7m bwlch, with these values obtained from LIDAR analysis and the resulting Hill Reclassifications post appearing on Mapping Mountains on the 24.05.17. Its adjacent peak of Mynydd
Garth Pwt was also analysed using LIDAR resulting in a 30.5m drop, based on a
397.8m summit and 367.3m bwlch. As LIDAR
gave Allt y Genlli as higher their respective bwlch positions and heights were
swapped resulting in Allt y Genlli being reclassified to a 390m Sub-Pedwar. The survey
with the Leica GS15 has now reversed this classification to pre LIDAR analysis.
The hill is a part of the Pumlumon range with its Cardinal Hill being Bryn Amlwg (SN 921 973) and is placed in the Region of Mid and West Wales
(Region B, Sub-Region B2). The hill is
situated to the south of the A 470 and is positioned between the small
communities of Carno to its west north-west and Clatter to its east.
Although the upper section of the hill is a part of
designated open access land it is also immersed in conifer plantation. The summit of the hill is encircled by a
forest track and for those determined souls who wish to visit; an approach from
the north using this track may be the best option.
The survey with the Leica GS15 resulted in a summit height of
395.76m and a bwlch height of 367.05m, with these values giving this hill 28.7m
of drop, which is insufficient for its retention as a 390m Sub-Pedwar.
The full details for the two hills are:
Cardinal Hill: Bryn
Amlwg
Name: Allt y Genlli
Summit Height: 395.8m
OS 1:50,000 map: 136
Summit Grid Reference:
SN 98508 95041
Drop: 28.7m
Cardinal Hill: Bryn
Amlwg
Name: Mynydd Garth Pwt
Summit Height: 397.8m
OS 1:50,000 map: 136
Summit Grid Reference:
SN 98154 94173
Drop: 72.1m
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:
Our thanks to John Barnard, Chris Crocker and Graham Jackson
for bringing the survey result of this hill to our attention
Myrddyn Phillips and Aled Williams (May 2018)
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