Carreg Waring (SH 537 390) – 30-99m Sub-Twmpau addition
There has been confirmation of an addition to the list of 30-99m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived by LIDAR analysis conducted by Myrddyn Phillips.
LIDAR image of Carreg Waring (SH 537 390) |
The criteria for the list that this addition
applies to are:
30-99m
Twmpau – Welsh hills at or above 30m
and below 100m in height that have 30m minimum drop, with an accompanying sub list entitled the 30-99m
Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or
above 30m and below 100m in height with 20m or more and below 30m of drop, with
the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
30-99m Twmpau by Myrddyn Phillips |
The name the hill is now listed by is Carreg Waring,
and this was derived by a combination of the
Ordnance Survey series of Six-Inch maps and local enquiry, and it is adjoined
to the Moel Hebog group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region
A1), and it is positioned with the
A497 road to its north and a minor road to its east, and has the town of Porthmadog
towards the east.
When the original 30-99m 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, as it was considered not to meet the criteria then used for this sub
category.
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 23m of drop, based on the
57m summit spot height that appeared on the Ordnance Survey Vector Map Local
hosted on the Geograph website and which was entitled the Interactive Coverage
Map and an estimated c 34m bwlch height, based on interpolation of 5m contouring
between 30m – 35m.
Extract from the Ordnance Survey 1:25,000 Explorer map |
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.
Therefore, the confirmation of the addition of
this hill to 30-99m Sub-Twmpau status is due to LIDAR analysis, resulting in a 57.15m
summit height and a 33.0m bwlch height, with these values giving this hill 24.1m
of drop, which is sufficient for it to be classified as a 30-99m Sub-Twmpau.
The full details for the hill are:
Group: Moel Hebog
Name: Carreg Waring
OS 1:50,000 map: 124
Summit Height: 57.15m (LIDAR)
Summit Grid Reference: SH 53734 39025 (LIDAR)
Bwlch Height: 33.0m (LIDAR)
Bwlch Grid Reference: SH 53892 38892 (LIDAR)
Drop: 24.1m (LIDAR)
Myrddyn Phillips (April 2024)
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