Pen y Bryn Mawr (SN 705 732)
There has been confirmation of a Summit Relocation to a hill that is listed in the Y Trichant – The 300m Hills of Wales and Y Trechol – The Dominant Hills of Wales, with the summit height, bwlch height and their locations, the drop, dominance and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips.
The forested summit of Pen y Bryn Mawr (SN 705 732) |
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.
Y Trichant - The 300m Hills of Wales by Myrddyn Phillips |
Y Trechol - The Dominant Hills of Wales by Myrddyn Phillips |
When the original 300m height band of Welsh P30 hills was published on Geoff Crowder’s v-g.me website, this hill was listed under the name of Cefn Blewog with a 341m summit height based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map and which is positioned at SN 70556 72711.
Extract from the Ordnance Survey 1:25,000 Explorer map |
The details of this hill were later re-examined and its summit position relocated to Pen y Bryn Mawr, this hill is due north of Cefn Blewog and although it does not possess a summit spot height on contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps, its uppermost 340m ring contour is larger than that given Cefn Blewog and therefore Pen y Bryn Mawr was listed with an estimated c 342m summit height, and when coupled with an emended c 224m bwlch height, these values gave Pen y Bryn Mawr an estimated c 118m of drop and 34.50% dominance.
LIDAR image of Pen y Bryn Mawr (SN 705 732) and Cefn Blewog (SN 705 727) |
The summit height produced by LIDAR analysis for
these two hills is given below:
341.619m at SN 70567 73222 for Pen y Bryn Mawr
340.660m at SN 70552 72709 for Cefn Blewog
This comes within the parameters of the Summit Relocations used within this page heading, these parameters are:
The term Summit Relocations applies when the hill’s high point is found to be positioned; in a different field, within a different map contour, to a different feature such as in a conifer plantation, to a different point where a number of potential summit positions are within close proximity, 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, or when natural ground or the natural and intact summit is confirmed compared to a higher point such as a raised field boundary that is judged to be a relatively recent man-made construct.
The Trimble GeoXH 6000 at the summit of Pen y Bryn Mawr |
The full details for the hill are:
Group: Elenydd
Name: Pen y Bryn Mawr
OS 1:50,000 map: 135,
147
Summit Height: 341.6m (LIDAR)
Summit Grid Reference (New Position): SN 70567 73222 (LIDAR)
Bwlch Height: 222.8m (LIDAR)
Bwlch Grid Reference: SN 72170 73551 (LIDAR)
Drop: 118.8m (LIDAR)
Dominance: 34.77% (LIDAR)
Myrddyn Phillips
(September 2021)
No comments:
Post a Comment