Wstrws (SN 389 502)
There has been a Summit Relocation to a hill that is listed in the Y Trichant – The 300m Hills of Wales, 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 Wstrws (SN 389 502) |
The criteria for the list that this summit
relocation applies to are:
Y Trichant
– The 300m Hills of Wales – Welsh
hills at or above 300m and below 400m in height that have 30m minimum drop, with an accompanying sub list entitled the
Sub-Trichant, with the criteria for this sub category being all Welsh hills at
or above 300m and below 400m in height with 20m or more and below 30m of drop. The
list is authored by Myrddyn Phillips with the Introduction to the list and the
renaming of it appearing on Mapping Mountains on the 13th May 2017,
and the Introduction to the Mapping Mountains publication of the list appearing
on the 1st January 2022.
Y Trichant - The 300m Hills of Wales by Myrddyn Phillips |
The name the hill is now listed by is Wstrws and
this was derived from the Tithe map, and it is adjoined to the Mynydd Bach
group of hills, which are situated in the western
part of South Wales (Region B, Sub-Region B1), and it is positioned with the A486 road to its
north-west and minor roads to its south and east, and has the village of
Post-mawr (Synod Inn) towards the north north-east.
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, 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 22m of drop, based on
the 308m summit spot height positioned at SN 38989 50309 that appears on the
contemporary Ordnance Survey 1:25,000 Explorer map, and an estimated c 286m
bwlch height, based on interpolation of 5m contouring between 285m – 290m.
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 309.1m positioned at SN 38967 50318.
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 Wstrws (SN 389 502) |
The height produced by LIDAR analysis to the
natural summit of this hill is 308.2m positioned at SN 38955 50296, and this
position in relation to the raised field boundary 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 considered 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 summit height produced by LIDAR
analysis is 308.2m and this is positioned at SN 38955 50296, this position is
not given a spot height on the contemporary Ordnance Survey 1:25,000 Explorer
map and is approximately 35 metres westward from where the 308m spot height
appears on the Ordnance Survey 1:25,000 Explorer map and approximately 22
metres south-westward from the high point of the raised field boundary.
The full details for the hill are:
Group: Mynydd Bach
Name: Wstrws
OS 1:50,000 map: 145
Summit Height: 308.2m (LIDAR)
Summit Grid Reference (New Position): SN 38955 50296 (LIDAR)
Bwlch Height: 286.3m (LIDAR)
Bwlch Grid Reference: SN 38557 50449 (LIDAR)
Drop: 21.9m (LIDAR)
Myrddyn Phillips
(January 2024)
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