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

Ash Tip (ST 031 663) – Dominant addition

There has been an addition to the list of the Y Trechol – The Dominant Hills of Wales, with the summit height, bwlch height and their locations, the drop, dominance and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Ash Tip (ST 031 663)

The criteria for the list that this addition 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, with the Introduction to the Mapping Mountains publication of this list appearing on the 3^rd December 2015.

The name the hill is now listed by is Ash Tip and this was derived from local enquiry, and it is adjoined to the Bro Morgannwg group of hills, which are situated in the southern part of South Wales (Region C, Sub-Region C2), and it forms a part of landscaped ground that once made up the Aberthaw quarry and lime works, and it is positioned with the B4265 road to its north, and has the small community of Sain Tathan (St Athan) towards the north-west.

When the original 30-99m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was not included in either the main P30 list or the Hills to be surveyed sub list, as contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps of the day showed the area that now makes up this hill as having no ring contours of note.

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

This area was re-examined when the OS Maps website became available online.  This is the replacement for OS Get-a-map and has contours at 5m intervals and for the majority of land comprising old mine workings it shows present day contours, as opposed to the blank space showed on the counterparts of the 1:50,000 Landranger and 1:25,000 Explorer maps.

Extract from the OS Maps website

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. 

The addition of Ash Tip to Dominant status is due to analysis of data on the OS Maps website coupled with LIDAR analysis and inspection of imagery on Google Maps and Google Earth with the conclusion that this hill is solid and stable.  LIDAR analysis has resulted in a 50.0m summit height and a 12.4m bwlch height, with these values giving this hill 37.6m of drop and 75.20% dominance, which is sufficient for the hill to be classified as a Dominant.

The full details for the hill are:

Group:  Bro Morgannwg

Name:  Ash Tip

OS 1:50,000 map:  170

Summit Grid Reference:  ST 03170 66338 (LIDAR)

Summit Height:  50.0m (LIDAR)

Bwlch Grid Reference:  ST 03298 66735 (LIDAR)

Drop Summit to Bwlch:  37.6m (LIDAR)

Drop Bwlch to ODN:  12.4m (LIDAR)

Dominance:  75.20%

Myrddyn Phillips (October 2019)