Sunday, 8 March 2020

Mapping Mountains – Summit Relocations – Y Pedwarau – The 400m Hills of Wales


Esgair Fraith (SN 650 483)

There has been a Summit Relocation to a hill that is listed in the Y Pedwarau – The 400m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis conducted by Aled Williams.

LIDAR image of Esgair Fraith (SN 650 483)

The criteria for the list that this summit relocation applies to are:

Y PedwarauThe 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 listed in 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 Esgair Fraith 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 encircled by minor roads with the Afon Teifi and the B4343 to its west and the A482 road to its south, and has the town of Llanbedr Pont Steffan (Lampeter) towards the west.

When the original 400m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was included in the accompanying Hills to be surveyed sub list with a summit height of 415m based on the spot height positioned at SN 64814 48226 that appears on the Ordnance Survey 1:25,000 Explorer map.

Extract from the Ordnance Survey 1:25,000 Explorer map

When the 1st edition of the Y Pedwarau was published by Europeaklist in May 2013 the hill appeared under the details given above using the six figure grid reference of SN 648 482.  With the ten figure grid reference based on the position of the 415m spot height used when the Y Pedwarau- The 400m Hills of Wales list was published on Mapping Mountains.

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 summit image for Esgair Fraith

The summit height produced by LIDAR analysis is 416.2m at SN 65077 48399, and this position in relation to that previously given comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies to any listed hill whose summit meets the following criteria; where there are a number of potential summit positions within close proximity and the highest point is not where previously given, 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, or when the summit of the hill is in a different field compared to where previously given, or when it is positioned to a different feature such as in a conifer plantation, or when the high point of the hill is placed within a different map contour compared to its previous listed position, or 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 that is judged to be a relatively recent man-made construct.

The height and position ascertained from LIDAR analysis is similar to data on the WalkLakes website which hosts an interactive Ordnance Survey map originated from the Ordnance Survey Open Data programme.  This map has many spot heights not on other publicly available Ordnance Survey maps and gives a 416m spot height for the summit of this hill positioned at SN 65079 48401.

Extract from the WalkLakes website

Therefore, the summit height produced by LIDAR analysis for this hill is 416.2m and is positioned at SN 65077 48399, this position is not given a spot height on contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps and is approximately 270 metres north-eastward from where the previously listed summit is positioned.


ills of Wales, and are reproduced below@
The full details for the hill are:

Group:  Elenydd

Name:  Esgair Fraith

OS 1:50,000 map:  146

Summit Height:  416.2m (LIDAR)

Summit Grid Reference (new position):  SN 65077 48399 (LIDAR) 
 
Bwlch Height:  386.5m (LIDAR)

Bwlch Grid Reference:  SN 65522 48403 (LIDAR)

Drop:  29.7m (LIDAR)


Myrddyn Phillips and Aled Williams (March 2020)



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