Lan Fawr (SN 692 501) – Pedwar reclassified to 400m
Sub-Pedwar
There has been a reclassification to the listing
of the Y Pedwarau – The 400m Hills of
Wales, with the summit height, bwlch height and their locations, the drop
and status of the hill derived from a Trimble GeoXH 6000 survey conducted on
the 5th January 2020 by Myrddyn Phillips with assistance from Rob
Woodall.
 |
| Lan Fawr (SN 692 501) |
The criteria for the list that this
reclassification applies to are:
Y Pedwarau – The 400m Hills of Wales.
Welsh hills at or above 400m and below 500m in height that have 30m
minimum drop, accompanying the main Y Pedwarau list are five categories of sub
hills, with this hill being reclassified to the 400m Sub-Pedwar category. The criteria for 400m Sub-Pedwar status being
all Welsh hills at or above 400m and below 500m in height that have 20m or more
and below 30m of drop. The list is co-authored by Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.
The name the hill is listed by is Lan Fawr, and it is adjoined to the Elenydd group of hills, which
are situated in the northern part of Mid and West Wales (Region B, Sub-Region
B2), and it is positioned with the Afon Teifi and the B4343 road to its north-west
and the A482 road to its south-west, and has the village of Llanbedr Pont
Steffan (Lampeter) towards the west.
When the 1st edition of the Y Pedwarau was published by Europeaklist
in May 2013, this hill was listed as a 400m Sub-Pedwar with 28m of drop, based
on a 429m summit height that appears as a spot height on the Ordnance Survey
1:50,000 Landranger and 1:25,000 Explorer map and a 401m bwlch height that
appeared as a spot height on the Ordnance Survey Vector Map Local hosted on the
Geograph website and which is entitled the Interactive Coverage Map and which
is positioned at SN 69498 50464. This
spot height is also shown on Ordnance Survey data that appears on the Magic
Maps website.
 |
| Extract from the Ordnance Survey 1:25,000 Explorer map |
The details for this hill were re-assessed when
the OS Maps website became available online.
This is the replacement for OS Get-a-map and has contours at 5m
intervals which are proving consistently more accurate compared to the 5m
contours that sometimes appear on Ordnance Survey 1:25,000 Explorer maps and
used to appear on the online Vector Map Local.
This re-assessment resulted in the hill being listed with an estimated c
30m of drop, based on interpolation of 5m bwlch contouring between 395m – 400m.
 |
| The Trimble GeoXH 6000 gathering data at the summit of Lan Fawr |
The 401m spot height that appears on the Ordnance
Survey Vector Map Local hosted on the Geograph website and which is entitled
the Interactive Coverage Map originates from a 1316ft (401.1m) imperial height
that appears on the Ordnance Survey series of Six-Inch maps. This seems to be a levelled height and was
not necessarily taken to the critical point of this bwlch. As a consequence of these re-assessments this
hill was reclassified to a Pedwar with an estimated c 30m of drop.
 |
| The Trimble GeoXH 6000 gathering data at the bwlch of Lan Fawr |
Therefore, the reclassification of this hill from Pedwar
back to 400m Sub-Pedwar status is due to a Trimble GeoXH 6000 survey, resulting
in a 427.4m summit height and a 398.3m bwlch height, with these values giving
this hill 29.1m of drop which is insufficient for it to be classified as a
Pedwar.
The full details for the hill are:
Group: Elenydd
Name: Lan Fawr
OS 1:50,000 map: 146
Summit Height: 427.4m
(Trimble GeoXH 6000)
Summit Grid Reference:
SN 69244 50156 (Trimble GeoXH 6000)
Bwlch Height: 398.3m (Trimble GeoXH 6000)
Bwlch Grid
Reference: SN 69493 50467 (Trimble GeoXH
6000)
Drop: 29.1m (Trimble
GeoXH 6000 summit and bwlch)
For the additions, reclassifications and deletions to Y Pedwarau – The 400m Hills of Wales reported
on Mapping Mountains since the May 2013 publication of the list by Europeaklist
please consult the following Change Registers:
Myrddyn Phillips and Aled Williams (May 2020)
No comments:
Post a Comment