Pen Rhiw Einon (SO 075
380)
There has been a Significant Height Revision 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.
%20-%20LIDAR%20hill%201.jpg) |
| LIDAR image of Pen Rhiw Einon (SO 075 380) |
The criteria for the list that this height revision applies
to are:
 |
| Y Trichant - The 300m Hills of Wales by Myrddyn Phillips |
The name the hill is now listed by is Pen Rhiw
Einon and this was derived from the Tithe map, and it is adjoined to the Mynydd
Epynt group of hills, which are situated in the central
part of South Wales (Region B, Sub-Region B1), and it is positioned encircled by minor roads, with the
B4520 road farther to its west and the A470 road farther to its east, and has
the small community of Erwyd (Erwood) towards the north north-east.
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 35m of drop, based on the 379m summit
spot height and the 344m bwlch spot height, with the latter appearing on the
contemporary Ordnance Survey 1:25,000 Explorer map.
%20-%201%2025000.jpg) |
| 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.
%20-%20LIDAR%20summit%202.jpg) |
| LIDAR summit image of Pen Rhiw Einon (SO 075 380) |
The summit height produced by LIDAR analysis is 376.4m
and is positioned at SO 07517 38090, and this comes within the parameters of
the Significant Height Revisions used within this page heading, these
parameters are:
The term Significant Height Revisions applies to
any listed hill whose interpolated height and Ordnance Survey or Harvey map
summit spot height has a 2m or more discrepancy when compared to the survey
result produced by the Trimble GeoXH 6000 or analysis of data produced via
LIDAR, also included are hills whose summit map data is missing an uppermost
ring contour when compared to the data produced by the Trimble or by LIDAR
analysis.
Therefore, the new listed summit height of this
hill is 376.4m and this was derived from LIDAR analysis, this is 2.6m lower than
the previously listed summit height of 379m, which was based on the spot height
that appears on the contemporary Ordnance Survey 1:50,000 Landranger and
1:25,000 Explorer map.
The full details for the
hill are:
Group: Mynydd Epynt
Name: Pen Rhiw Einon
OS 1:50,000 map: 160
Summit Height (New
Height): 376.4m (LIDAR)
Summit Grid
Reference: SO 07517 38090 (LIDAR)
Bwlch Height: 345.6m (LIDAR)
Bwlch Grid
Reference: SO 07458 37640 (LIDAR)
Drop: 30.8m (LIDAR)
Myrddyn Phillips (August
2024)