Saturday 6 May 2023

Mapping Mountains – Hill Reclassifications – Y Trichant – The 300m Hills of Wales


Pt. 383m (SN 643 476) – Sub-Trichant addition

There has been an addition to the list of Y Trichant – The 300m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail on contemporary maps produced from Ordnance Survey data and LIDAR analysis conducted by Myrddyn Phillips. 

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

Y Trichant – The 300m Hills of Wales – 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, and the Introduction to the Mapping Mountains publication of the list appearing on the 1st January 2022. 

Y Trichant - The 300m Hills of Wales by Myrddyn Phillips

The hill is being listed by the point (Pt. 383m) notation as an appropriate name for it either through local enquiry and/or historic research has not been found by the author, and it is adjoined to the Esgair Wen group of hills, which are situated in the central part of South Wales (Region B, Sub-Region B1), and it is positioned enclosed by minor roads, with the B4343 road farther to its north-west and the A482 road farther to its south-west, and has the town of Llanbedr Pont Steffan (Lampeter) towards the west.

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 considered not to meet the criteria then used for this sub category.

After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed with 18m of drop, based on the 383m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and the 365m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

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.

Therefore, the addition of this hill to Sub-Trichant status is due to detail on contemporary maps produced from Ordnance Survey data and LIDAR analysis, resulting in a 383m summit height and a 361.9m bwlch height, with these values giving this hill 21m of drop, which is sufficient for it to be classified as a Sub-Trichant. 

 

The full details for the hill are: 

Group:  Esgair Wen 

Name:  Pt. 383m 

OS 1:50,000 map:  146

Summit Height:  383m (spot height)                                                           

Summit Grid Reference:  SN 64358 47680 (spot height) 

Bwlch Height:  361.9m (LIDAR) 

Bwlch Grid Reference:  SN 64555 47855 (LIDAR) 

Drop:  21m (spot height summit and LIDAR bwlch) 

 

Myrddyn Phillips (May 2023)

 

 

 

 

 

  

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