Saturday, 11 March 2017

Mapping Mountains – Hill Reclassifications – Y Pedwarau

Esgair Wen (SN 807 664) - Pedwar reclassified to 400m Sub-Pedwar

There has been a reclassification to the listing of the 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 Elenydd group of hills which is one of the wildest hill ranges in Wales, with its Cardinal Hill being Drygarn Fawr (SN 862 584) and is placed in the Region of Mid and West Wales (Region B, Sub-Region B2).  The hill is positioned between the Claerwen Reservoir to its east and Llyn Egnant to its west north-west, with any town of size a long way away.

Whatever way one approaches, it is relatively remote for a Welsh hill with access from the north-west probably being the easiest with a track heading due south leaving the end of the minor paved road that culminates to the north of Llyn Egnant.  It is approximately 2km from this track to the summit of the hill, and although not great in distance the underfoot conditions are prone to be rough.

The name of the hill is Esgair Wen 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 31m of drop based on its 496m Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer summit spot height and the 465m bwlch spot height that appears on the Ordnance Survey enlarged map hosted on the Geograph website.

As Aled was analysing other hills in the vicinity against LIDAR data, he did likewise with Esgair WenLIDAR (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:

Esgair Wen

Summit Height:  494.6m

Summit Grid Reference:  SN 80767 66481

Bwlch Height:  464.7m

Bwlch Grid Reference:  SN 80121 66300

Drop:  29.9m

Therefore, the 494.6m LIDAR data produced for the summit position at SN 80767 66481 and the 464.7m LIDAR data produced for the bwlch position at SN 80121 66300 is insufficient for this hill to retain its Pedwar status, and therefore it is reclassified to a 400m Sub-Pedwar with 29.9m of drop, and the list of the Y Pedwarau will be updated accordingly.

The full details for the hill are:

Cardinal Hill:  Drygarn Fawr  

Summit Height:  494.6m (LIDAR data)  

Name:  Esgair Wen  

OS 1:50,000 map:  135, 136, 147  

Summit Grid Reference:  SN 80767 66481  

Drop:  29.9m (LIDAR data)  

This now brings the overall total for Y Pedwarau to 445 hills with seven additions, and nine 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 also having 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:



Esgair Wen (LIDAR data) (SN 807 664) Pedwar reclassified to 400m Sub-Pedwar with 29.9m drop

Myrddyn Phillips and Aled Williams (March 2017)

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