Mapping Mountains – Hill Reclassifications – 30-99m Twmpau

Tor Gro (SS 462 934) – 30-99m Twmpau addition

There has been confirmation of an addition to the list of 30-99m Twmpau due to LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Tor Gro

The criteria for the listing that this addition applies to are:

30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.

This hill did not appear in the original Welsh P30 lists when published on Geoff Crowder’s v-g.me website, even though map details gave it 30m of drop with a 79m summit and 49m bwlch spot height that appear on the Ordnance Survey 1:25,000 Explorer map.

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

The details relating to this hill were soon readdressed when these lists were standardised and drop values and interpolated heights included, and it then appeared as a P30 and was later also included as a Lesser Dominant when the Gŵyr group of hills were initially listed on the 07.05.12.

The name of the hill is Tor Gro, and it is adjoined to the Gŵyr group of hills, which are situated in the western part of South Wales (Region C, Sub-Region C1), and it is positioned overlooking the Landimore Marsh to its north and the Burry Pill stream to its south, and has the small community of Llanmadog towards the west and Landimore towards the south-east.

If wanting to visit this hill permission to do so should be sought as it is not a part of designated open access land, for those wishing to do so the nearest public footpath giving access toward the summit is to the south and south-east of it.

The confirmation of this addition is due to LIDAR analysis conducted by Myrddyn Phillips.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales. 

The LIDAR analysis gives the hill the following details:

Name:  Tor Gro

Summit Height:  79.6m

Summit Grid Reference:  SS 46245 93479

Bwlch Height:  48.1m

Bwlch Grid Reference:  SS 46183 92937

Drop:  31.6m

Therefore, the 79.6m LIDAR analysis for the summit position at SS 46245 93479 and the 48.1m LIDAR analysis for the bwlch position at SS 46183 92937 gives this hill 31.6m of drop, which confirms its 30-99m Twmpau status.

LIDAR summit image of Tor Gro

The full details for the hill are:

Group:  Gŵyr

Name:  Tor Gro

OS 1:50,000 map:  159

Summit Height:  79.6m (LIDAR)

Summit Grid Reference:  SS 46245 93479 (LIDAR)

Bwlch Height:  48.1m (LIDAR)

Bwlch Grid Reference:  SS 46183 92937 (LIDAR)

Drop:  31.6m (LIDAR)

Myrddyn Phillips (December 2018)