Mapping Mountains – Hill Reclassifications – Y Trechol – The Dominant Hills of Wales

Cae Ddu Main (SN 622 983) – Lesser Dominant addition

There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales, with the summit height, its location, the drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Cae Ddu Main

The criteria for the list that this reclassification applies to are:

Y Trechol – The Dominant Hills of Wales – Welsh P30 hills whose prominence equal or exceed half that of their absolute height.  With the criteria for Lesser Dominant status being those additional Welsh P30 hills whose prominence is between one third and half that of their absolute height.  The list is authored by Myrddyn Phillips with the Introduction to the start of the Mapping Mountains publication of this list appearing on the 3^rd December 2015.

When the original Welsh 100m P30 list was published on Geoff Crowder’s v-g.me website the summit location of this hill was given to the 102m spot height that is positioned at SS 619 984 on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps.  When this list was standardised with interpolated height and drop values included this hill was listed with c 30m of drop based on the 102m spot height, with these values insufficient for Lesser Dominant status.  However, the 1:25,000 Explorer map has a small uppermost 105m ring contour to the east of the 102m spot height, which prompted the summit relocation of this hill.

The name of the bounded land where the summit of this hill is situated is Cae Ddu Main and this was derived from the Tithe map, and it is this name that the hill is now listed by.  The hill is adjoined to the Mynydd Penlle’rcastell group of hills, which are situated in the western part of South Wales (Region C, Sub-Region C1), and is positioned with the A483 road to its immediate west and the A48 and M4 to its north, and has the village of Penlle’r-gaer to its north.

If wanting to visit the hill permission to do so should be sought as the summit area is not a part of designated open access land, for those wishing to do so an approach from the north may be feasible.

LIDAR summit image of Cae Ddu Main

The summit height produced by LIDAR analysis is 106.9m to remaining natural ground and is positioned at SN 62212 98337, this position is approximately 290 metres east from where the summit was originally listed at the position of the 102m spot height, with the height produced by LIDAR to the natural bwlch being 69.1m positioned at SN 62051 00000, with these values giving this hill 37.8m of drop and 35.34% dominance, which is sufficient for this hill to be classified as a Lesser Dominant.

LIDAR bwlch image of Cae Ddu Main

The full details for the hill are:

Group:  Mynydd Penlle’rcastell

Name:  Cae Ddu Main

OS 1:50,000 map:  159

Summit Grid Reference:  SN 62212 98337 (LIDAR, remaining natural high point)

Summit Height:  106.9m (LIDAR, remaining natural high point)

Bwlch Grid Reference:  SN 62051 00000 (LIDAR, natural bwlch)

Drop Summit to Bwlch:  37.8m (LIDAR)

Drop Bwlch to ODN:  69.1m (LIDAR, natural bwlch)

Dominance:  35.34% (LIDAR)

Myrddyn Phillips (February 2019)