Thursday, 8 December 2016

Mapping Mountains – Hill Reclassifications – Yr Uchafion


Esgair y Llyn (SN 841 701) - Uchaf addition

There has been a new addition to the listing of Yr Uchafion instigated from map study and confirmed from LIDAR data analysed by Aled Williams.  Yr Uchafion is the draft title for a list of the Welsh 500m P15s that takes in all hills in Wales at or above 500m that have a minimum of 15m of drop, the list is a joint compilation with Aled Williams.  Details relating to this list were published on the Mapping Mountains site in November 2015.

The hill is situated in the Elenydd group of hills in the central part of Mid and West Wales.  This grouping of hills forms one of the wildest in Wales and takes in some of the most remote hills in the country.  The hill is situated in an immense grassland of moor and tussocks with Llyn Cerrigllwydion Isaf to its south-east and the higher summits of Cnapyn Drawsffos (SN 834 706) to its north-west and Blaen Rhestr (SN 843 693) towards its south.  Any towns or villages are a far distance away with Ysbyty Ystwyth towards the west and Rhaeadr Gwy (Rhayader) towards the east.

The hill can be accessed from its north-east via a track that leads to the farmhouse of Glanhirin, a path then leads toward and up the north-eastern ridge of Blaen Rhestr.  However, an alternate route would be using the Monks Trod, which is an ancient route across the hills developed by the Cistercian monks as a bi-way between the abbeys of Cwm-Hir and Strata Florida.  Whichever way is chosen it leads into land that is open and somewhat featureless.

The name of the hill is Esgair y Llyn and its inclusion as an Uchaf was spotted by Aled as the Ordnance Survey enlarged mapping on the Geograph website gives this hill a 529m summit spot height and a 513m bwlch spot height, this 16m of drop is sufficient to enter the list of Uchafion. 

As Aled was analysing other hills in the vicinity against LIDAR data, he did likewise with Esgair y Llyn.  LIDAR (Light Detection & Ranging) is highly accurate height data that is now freely available for much of England and Wales, and as mentioned in the first paragraph of this post; if Esgair y Llyn has a minimum of 15m of drop it would be included in the listing of Welsh hills at or over 500m in height that has a minimum of 15m of drop, and has the working title of Yr Uchafion.

Aled’s analysis of LIDAR data gave the hill a 528.8m summit height at SN 84118 70177, and a 513.3m bwlch height at SN 83811 70087, these values give this hill 15.5m of drop which is sufficient for qualification as an Uchaf.

This now revises the total in Yr Uchafion which will be updated accordingly and the hill is now listed as an Uchaf.


The full details for the hill are:

Cardinal Hill:  Carn yr Hyrddod

Summit Height:  528.8m (LIDAR data)

Name:  Esgair y Llyn

OS 1:50,000 map:  135, 136, 147

Summit Grid Reference:  SN 84118 70177 
  
Drop:  15.5m (LIDAR data)



The reclassifications to Yr Uchafion / The Welsh 500m P15s reported on Mapping Mountains are ills of wales as follows:



UCHAF ADDITIONS


Esgair y Llyn (LIDAR data) (SN 841 701) added as an Uchaf with 15.5m of drop.



UCHAF RECLASSIFICATIONS




UCHAF DELETIONS





Myrddyn Phillips and Aled Williams (December 2016)





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