Wednesday 31 July 2019

Mapping Mountains – Hill Reclassifications – Y Trichant


Llanbradach Tip (ST 138 913) – Sub-Trichant addition

There has been an addition of a hill to the Y Trichant list, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Llanbradach Tip (ST 138 913)

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

Y Trichant – 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 13th May 2017.

The name this hill is listed by is Llanbradach Tip and as its name implies the hill is the result of mine spoil and it is the western of three pyramidal tips, and it is adjoined to the Cymoedd Gwent group of hills, which are situated in the eastern part of South Wales (Region C, Sub-Region C2), and is positioned with the B4263 road to its south-west and the A469 road and the Afon Rhymni (Rhymney River) to its east, and has the small community of Llanbradach towards its south-east.

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was not included in the Hills to be surveyed sub list as it was thought not to meet the criteria then used; however this sub list has now been standardised and interpolated heights and drop values also included in the main P30 and the accompanying sub list.

When this list was standardised and interpolated heights also included the area surrounding this hill was re-assessed but as the Ordnance Survey 1:25,000 Explorer map shows the hill to have no contours and the 1:50,000 Landranger map shows the hill with two ring contours its drop value was difficult to estimate.

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

Extract from the Ordnance Survey 1:50,000 Landranger 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.

The addition of this hill to Sub-Trichant status is due to LIDAR analysis, resulting in a 331.3m summit height and a 310.4m bwlch height, with these values giving this hill 20.9m of drop which is sufficient for it to be classified as a Sub-Trichant.

 
The full details for the hill are:

Group:  Cymoedd Gwent

Name:  Llanbradach Tip

OS 1:50,000 map:  171

Summit Height:  331.3m (LIDAR)

Summit Grid Reference:  ST 13843 91345 (LIDAR)

Bwlch Height:  310.4m (LIDAR)

Bwlch Grid Reference:  ST 13784 91419 (LIDAR)
 
Drop:  20.9m (LIDAR)


Myrddyn Phillips (July 2019)




No comments: