Mapping Mountains – Summit Relocations – Y Trichant – The 300m Hills of Wales

Moelfre (SN 326 361) 

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 Moelfre (SN 326 361)

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 13^th May 2017, and the Introduction to the Mapping Mountains publication of the list appearing on the 1^st January 2022. 

Y Trichant - The 300m Hills of Wales by Myrddyn Phillips

The name the hill is listed by is Moelfre, and it is adjoined to the Mynydd Pencarreg group of hills, which are situated in the south-western part of South Wales (Region B, Sub-Region B1), and it is positioned with minor roads to its north-west, west and south, and the B4333 road to its east, and has the town of Castell Newydd Emlyn (Newcastle Emlyn) towards the north north-west.

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was included in the main P30 list with a summit height of 335m, based on the spot height that appears on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map.

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 104m of drop, based on the 335m summit spot height positioned at SN 32648 36095 and the 231m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

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 335.4m positioned at SN 32685 36114.  However, although this is positioned atop an ancient tumulus which under the protocols used for this list qualifies for the height of a hill, LIDAR contouring implies the height has been artificially raised by a field boundary positioned on the tumulus 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 Moelfre (SN 326 361)

The height produced by LIDAR analysis to the qualifying summit of this hill is 335.3m positioned at SN 32616 36119 and SN 32619 36117, 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 335.3m and this is positioned at SN 32616 36119 and SN 32619 36117, this position is not given a spot height on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and is approximately 33 metres north-westward from where the 335m spot height appears and approximately 70 metres westward from the high point of the raised field boundary. 

 

The full details for the hill are:

Group:  Mynydd Pencarreg 

Name:  Moelfre 

OS 1:50,000 map:  145

Summit Height:  335.3m (LIDAR)                                                           

Summit Grid Reference (New Position):  SN 32616 36119 & SN 32619 36117 (LIDAR)

Bwlch Height:  231.0m (LIDAR) 

Bwlch Grid Reference:  SN 41888 33712 (LIDAR) 

Drop:  104.4m (LIDAR)

 

Myrddyn Phillips (May 2024)