Mapping Mountains – Hill Reclassifications – Y Trichant

Allt y Genlli (SN 985 950) – Trichant reinstated to Sub-Trichant

There has been a reclassification to the listing of Y Trichant due to a survey with a Leica GS15 conducted by John Barnard, Chris Crocker and Graham Jackson.  Y Trichant is the title for the list of 300m hills of Wales and takes in all Welsh hills at or above 300m and below 400m in height that have a minimum 30m of drop, with the introduction to the re-naming of this list appearing on MappingMountains on the 13^th May 2017.

Accompanying the main Y Trichant list is a category of sub hills entitled the Sub-Trichant, the criteria for Sub-Trichant status being all Welsh hills at or above 300m and below 400m in height that have 20m or more and below 30m of drop.

The name of the hill is Allt y Genlli and prior to the survey with the Leica GS15 the hill was listed with 73.2m of drop, based on a 398.9m summit and 325.7m bwlch, with these values obtained from LIDAR analysis.  Its adjacent peak of Mynydd Garth Pwt was also analysed using LIDAR resulting in a 30.5m drop, based on a 397.8m summit and 367.3m bwlch.  As LIDAR gave Allt y Genlli as higher their respective bwlch positions and heights were swapped resulting in Allt y Genlli being reclassified to a Trichant.  The survey with the Leica GS15 has now reversed this classification to pre LIDAR analysis.

The hill is a part of the Pumlumon range with its Cardinal Hill being Bryn Amlwg (SN 921 973) and is placed in the Region of Mid and West Wales (Region B, Sub-Region B2).  The hill is situated to the south of the A 470 and is positioned between the small communities of Carno to its west north-west and Clatter to its east. 

Although the upper section of the hill is a part of designated open access land it is also immersed in conifer plantation.  The summit of the hill is encircled by a forest track and for those determined souls who wish to visit; an approach from the north using this track may be the best option.

The survey with the Leica GS15 resulted in a summit height of 395.76m and a bwlch height of 367.05m, with these values giving this hill 28.7m of drop, which is insufficient for its retention as a Trichant.

 

The full details for the two hills are:

Cardinal Hill:  Bryn Amlwg

Name:  Allt y Genlli

Summit Height:  395.8m

OS 1:50,000 map:  136

Summit Grid Reference:  SN 98508 95041 

 

Drop:  28.7m

Cardinal Hill:  Bryn Amlwg

Name:  Mynydd Garth Pwt

Summit Height:  397.8m

OS 1:50,000 map:  136

Summit Grid Reference:  SN 98154 94173 

 

Drop:  72.1m

My thanks to John Barnard, Chris Crocker and Graham Jackson for bringing the survey result of this hill to my attention

Myrddyn Phillips (May 2018)