Cae Pen y Cefn (SH 532 377)
There has been a Summit Relocation to a hill that
is listed in the 30-99m Twmpau, with the summit height, bwlch height
and their locations, the drop and status of the hill derived from LIDAR
analysis conducted by Myrddyn Phillips.
LIDAR image of Cae Pen y Cefn (SH 532 377) |
The criteria for the list that this summit
relocation 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 Cae Pen y
Cefn and this was derived from the Tithe map, 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 a minor road to its north and south, and the A497 road farther
to its north, and has the town of Porthmadog towards the east north-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 20m of drop, based on
the 58m summit spot height that appears on the contemporary Ordnance Survey
1:25000 Explorer map and which is positioned at SH 53282 37746, and an
estimated c 38m bwlch height, based on interpolation of 5m contouring between 35m
– 40m.
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.
LIDAR analysis gives the highest ground on this
hill as 58.5m positioned at SH 53278 37755.
However, this is a part of a raised field boundary and protocols dictate
that as this is deemed a relatively recent man-made construct such ground is
discounted from the height of a hill.
LIDAR summit image of Cae Pen y Cefn (SH 532 377) |
The height produced by LIDAR analysis to the
highest remaining natural ground on this hill is 57.8m and this is positioned
at SH 53267 37729, and this comes within the parameters of the Summit Relocations used
within this page heading, these parameters are:
The term Summit Relocations applies when the high
point of the hill is found to be positioned; in a different field, to a
different feature such as in a conifer plantation, within a different map contour, to a
different point where a number of potential summit positions are within close
proximity, when natural ground or the natural and intact summit of a hill is
confirmed compared to a higher point such as a raised field boundary or covered
reservoir that is judged to be a relatively recent man-made construct, or a
relocation of approximately 100 metres or more in distance from either the
position of a map spot height or from where the summit of the hill was
previously thought to exist.
Therefore, the height produced by LIDAR analysis
to the highest remaining natural ground on this hill is 57.8m and is positioned
at SH 53267 37729, this
position is relatively close to where the spot height appears on the
contemporary Ordnance Survey 1:25,000 Explorer map, and is approximately 26
metres south-westward from where the high point of the raised field boundary is
positioned.
The full details for the hill are:
Group: Moel Hebog
Name: Cae Pen y Cefn
OS 1:50,000 map: 124
Summit Height: 57.8m (LIDAR)
Summit Grid Reference (New Position): SH 53267 37729 (LIDAR)
Bwlch Height: 37.3m (LIDAR)
Bwlch Grid Reference: SH 53729 38357 (LIDAR)
Drop: 20.5m (LIDAR)
Myrddyn Phillips (May
2024)
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