Friday, 17 March 2017

Mapping Mountains – Hill Reclassifications – Y Pedwarau


Carreg y Gwynt (SN 956 776) - Pedwar reclassified to 400m Sub-Pedwar

There has been a reclassification to the listing of Y Pedwarau with a Pedwar being reclassified to the ranks of 400m Sub-Pedwar by analysis of LIDAR data by Aled Williams.  The 400m Sub-Pedwarau is one of five categories of sub hills that accompany the main Y Pedwarau list, with the criteria for 400m Sub-Pedwar status being all Welsh hills at or above 400m and below 500m in height with 20m or more and below 30m of drop.

The hill is situated in the Pegwn Mawr group with its Cardinal Hill being Garreg Lwyd (SN 942 733) and is placed in the Region of Mid and West Wales (Region B, Sub-Region B1).  The hill is positioned between the small community of Llangurig to the west north-west and the town of Llanidloes to the north.

The hill can be ascended from the north, south or east where public footpaths leave minor narrow roads and circumvent its summit.  As the hill is not a part of open access land permission to visit its summit should be sought.

The name of the hill is Carreg y Gwynt and prior to the analysis of LIDAR data and its subsequent listing as a 400m Sub-Pedwar it had been listed as a Pedwar with 32m of drop based on a 104ft (31.7m) basic levelling survey conducted by Myrddyn Phillips on the 23.04.04.

As Aled was analysing other hills in the vicinity against LIDAR data, he did likewise with Carreg y GwyntLIDAR (Light Detection & Ranging) is highly accurate height data that is now freely available for much of England and Wales.

Aled’s analysis of LIDAR data gives the hill the following details:


Carreg y Gwynt

Summit Height:  426.7m

Summit Grid Reference:  SN 95698 77665

Bwlch Height:  398.6m

Bwlch Grid Reference:  SN 95153 78738

Drop:  28.1m


Therefore, the 426.7m LIDAR data produced for the summit position at SN 95698 77665 and the 398.6m LIDAR data produced for the bwlch position at SN 95153 78738 is insufficient for this hill to retain its Pedwar status, and therefore it is reclassified to a 400m Sub-Pedwar with 28.1m of drop, and the list of the Y Pedwarau will be updated accordingly.


The full details for the hill are:

Cardinal Hill:  Garreg Lwyd

Summit Height:  426.7m (LIDAR data)  

Name:  Carreg y Gwynt  

OS 1:50,000 map:  136, 147  

Summit Grid Reference:  SN 95698 77665  

Drop:  28.1m (LIDAR data)  


This now brings the overall total for Y Pedwarau to 444 hills with seven additions, and ten reclassifications to 400m Sub-Pedwar status since publication of the list by Europeaklist in May 2013.  The hill will be taken out of the Pedwar list and added to the 400m Sub-Pedwar list in forthcoming publications.  The list of Pedwar hills is available from the Haroldstreet website (January 2014) with all subsequent changes available via the Mapping Mountains site, with the list having also commenced publication on Mapping Mountains on the 30.01.17.

The list of additions and reclassifications from the Pedwar list since the 1st edition of Y Pedwarau was published by Europeaklist are as follows:



PEDWAR ADDITIONS













PEDWAR RECLASSIFICATIONS











Carreg y Gwynt (LIDAR data) (SN 956 776) Pedwar reclassified to 400m Sub-Pedwar with 28.1m of drop



Myrddyn Phillips and Aled Williams (March 2017)




No comments: