Mapping Mountains – Hill Reclassifications – Y Trichant

Caer Eini (SJ 000 412) – Sub-Trichant reclassified to Trichant

There has been confirmation of a reclassification to a hill listed in the Y Trichant, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by a Trimble GeoXH 6000 survey and LIDAR analysis conducted by Myrddyn Phillips, with the former taking place on the 25^th October 2014.

Caer Eini (SJ 000 412)

The criteria for the list that this reclassification 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 13^th May 2017.

The name of the hill is Caer Eini and it is adjoined to the Arenig group of hills, which are situated in the central part of North Wales (Region A, Sub-Region A3), and it is positioned with the A494 road to its south-east, and has the town of Y Bala towards the south-west. 

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was included in the Hills to be surveyed sub list that accompanied the main P30 list, as it did not meet the criteria then used for the main P30 list. 

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 31m of drop, based on the 365m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and the 334m bwlch spot height that appears on the Ordnance Survey Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map.

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph website

However, it was not until the survey with the Trimble GeoXH 6000 and when 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. 

LIDAR bwlch image of Caer Eini

The confirmation of the reclassification of Caer Eini to Trichant status is due to a survey with the Trimble GeoXH 6000 and LIDAR analysis, resulting in a 365.7m summit height and a 334.4m bwlch height, with these values giving this hill 31.3m of drop which is sufficient for it to be classified as a Trichant.

The full details for the hill are:

Group:  Arenig

Name:  Caer Eini

OS 1:50,000 map:  125

Summit Height:  365.7m (converted to OSGM15)

Summit Grid Reference:  SJ 00048 41275

Bwlch Height:  334.4m (LIDAR)

Bwlch Grid Reference:  SH 99599 41003 (LIDAR)

Drop:  31.3m (Trimble summit and LIDAR bwlch)

For details on the summit survey of this hill

Myrddyn Phillips (November 2019)