Bryn Hafod y Llan (SH 945 531) – 390m Double Sub-Pedwar
addition
There has been an addition of a hill to the list
of the Y Pedwarau, with the summit height, bwlch height
and their locations, the drop and status of the hill confirmed by LIDAR
analysis initially conducted by Aled Williams and subsequently by Myrddyn
Phillips.
 |
| LIDAR image of Bryn Hafod y Llan (SH 945 531) |
The criteria for the list that this addition
applies to are:
Y Pedwarau – Welsh hills at or above
400m and below 500m in height with 30m minimum drop, accompanying the main Y Pedwarau list are five categories of
sub hills, with this hill being included in the 390m Double Sub-Pedwar category. The criteria for 390m Double Sub-Pedwar status being all Welsh hills at or above
390m and below 400m in height that have 20m or more and below 30m of drop. The list is co-authored by Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.
The name of the hill is Bryn Hafod y Llan, and it
is adjoined to the Mynydd Hiraethog group of hills, which are situated in the north-eastern part of
North Wales (Region A, Sub-Region A2), and
it is positioned with the A5 road to its south and the B4501 road to its east,
and has the Alwen Reservoir to the north-east and the village of Cerrigydrudion
towards the south.
When the original 300m height band of Welsh P30
hills were published on Geoff Crowder’s v-g.me website this hill was not included
in the Hills to be surveyed sub list
that accompanied the main P30 list, as it did not meet the criteria then used for
this sub category.
 |
| Extract from the Ordnance Survey 1:25,000 Explorer map |
After the sub list was standardised, and
interpolated heights and drop values also included the details for this hill
were re-evaluated and it was listed with an estimated c 18m of drop, based on
an estimated summit height of c 397m and a bwlch height of 379m that appears as
a spot height on the Ordnance Survey Vector Map Local hosted on the Geograph
website and which is entitled the Interactive Coverage Map.
 |
| Extract from the Ordnance Survey Vector Map Local hosted on the Geograph website |
However, it was not until LIDAR became available
that the details for this hill could be accurately re-assessed. The LIDAR (Light Detection & Ranging)
technique produced highly accurate height data that is now freely available for
much of England and Wales.
The addition of Bryn Hafod y Llan to 390m Double Sub-Pedwar status is due to
LIDAR analysis, resulting in a 398.7m summit height and a 378.5m bwlch height,
with these values giving this hill 20.1m of drop which is sufficient for it to
be classified as a 390m Double Sub-Pedwar.
The full details for the hill are:
Group: Mynydd
Hiraethog
Name: Bryn Hafod y
Llan
OS 1:50,000 map: 116
Summit Height: 398.7m
(LIDAR)
Summit Grid Reference:
SH
94590 53115 (LIDAR)
Bwlch Height:
378.5m (LIDAR)
Bwlch Grid Reference:
SH 94564 52682 (LIDAR)
Drop: 20.1m (LIDAR)
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
available and following Change Registers:
Myrddyn Phillips and Aled Williams (September 2019)
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