Myrddyn Phillips - Mapping Mountains: Rhos Scythlyn

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Friday, 2 May 2025

Mapping Mountains – Significant Name Changes – The Welsh P15s

Rhos Scythlyn (SN 430 361)

There has been a Significant Name Change to a hill that is listed in The Welsh P15s, 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 Rhos Scythlyn (SN 430 361)

The criteria for the list that this name change applies to are:

The Welsh P15s – Welsh hills with 15m minimum drop, irrespective of their height, with an accompanying sub list entitled the Welsh Sub-P15s, with the criteria for this sub category being all Welsh hills with 14m or more and below 15m of drop. The list is authored by Myrddyn Phillips, with the Introduction to the list appearing on Mapping Mountains on the 10^th May 2019.

The Welsh P15s by Myrddyn Phillips

The hill 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-east, west and south, and the B4459 road to its east, and has the town of Llandysul towards the north north-west.

When the listing that became known as The Welsh P15s was being compiled, this hill was included in the main list under the point (Pt. 256m) notation with an estimated c 18m of drop, based on the 256m summit spot height positioned at SN 43015 36148 that appears on the Ordnance Survey 1:25,000 Explorer map, and an estimated c 238m bwlch height, based on interpolation of 5m contouring between 235m – 240m.

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

As the summit of this hill comprises bounded land the details for it were examined on the Tithe map. The term Tithe map is generally given to a map of a Welsh or English parish or township and which was prepared after the 1836 Tithe Commutation Act. This act allowed tithes to be paid in cash rather than goods. The Tithe maps gave names of owners and occupiers of land in each parish and importantly for place-name research they also included the name of enclosed land. This enclosed land is usually based on a field system, however not every field is given a name, but many are and especially so in Wales.

Extract from the Tithe map

The enclosed land where the summit of this hill is situated is given the number 298 on the Tithe map, this can be cross referenced against the apportionments; it is these apportionments that give the name of the owner or occupier of the land as well as the name of the land. The land where the summit of this hill is situated is named as Rhos Scythlyn in the apportionments, with the details on the Tithe map appearing in the parish named as Llanfihangel-ar-bryn and in the county named as Carmarthenshire.

Extract from the apportionments

Therefore, the name this hill is now listed by in The Welsh P15s is Rhos Scythlyn and this was derived from the Tithe map.

The full details for the hill are:

Group: Mynydd Pencarreg

Name: Rhos Scythlyn

Previously Listed Name: Pt. 256m

OS 1:50,000 map: 146

Summit Height: 257.0m (LIDAR)

Summit Grid Reference: SN 43043 36164 (LIDAR)

Bwlch Height: 239.3m (LIDAR)

Bwlch Grid Reference: SN 41655 34356 (LIDAR)

Drop: 17.7m (LIDAR)

Myrddyn Phillips (May 2025)

Mapping Mountains – Summit Relocations – The Welsh P15s

Rhos Scythlyn (SN 430 361)

There has been a Summit Relocation to a hill that is listed in the The Welsh P15s, 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 Rhos Scythlyn (SN 430 361)

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

The Welsh P15s by Myrddyn Phillips

The name the hill is now listed by is Rhos Scythlyn, and this was derived from the Tithe map, 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-east, west and south, and the B4459 road to its east, and has the town of Llandysul towards the north north-west.

When the listing that became known as The Welsh P15s was being compiled, this hill was included in the main list with an estimated c 18m of drop, based on the 256m summit spot height positioned at SN 43015 36148 that appears on the Ordnance Survey 1:25,000 Explorer map, and an estimated c 238m bwlch height, based on interpolation of 5m contouring between 235m – 240m.

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 257.35m positioned at SN 42955 36082. However, this is to the top of a raised field boundary 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 Rhos Scythlyn (SN 430 361)

The height produced by LIDAR analysis to the summit of this hill is 257.0m and is positioned at SN 43043 36164, and this 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 either on Ordnance Survey maps or interactive mapping, 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 the de-twinning of a summit, 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 257.0m and is positioned at SN 43043 36164, this position is not given a spot height on the contemporary Ordnance Survey 1:25,000 Explorer map and is approximately 28 metres north-westward from where the 256m spot height is positioned and approximately 90 metres north-westward from the high point of the raised field boundary.