Mapping Mountains – Hill Reclassifications – Y Pedwarau – The 400m Hills of Wales

Moel Wnog (SH 735 440) – Pedwar reclassified to 400m Sub-Pedwar

There has been a reclassification to the listing of the Y Pedwarau – The 400m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail produced by Joe Nuttall in his surface analysis progamme, with subsequent LIDAR analysis conducted by the DoBIH team and independently by Aled Williams and Myrddyn Phillips. 

LIDAR image of Moel Wnog (SH 735 440)

The criteria for the list that this reclassification applies to are:

Y Pedwarau – The 400m Hills of Wales.  Welsh hills at or above 400m and below 500m in height that have 30m minimum drop, accompanying the main Y Pedwarau list are five categories of sub hills, with this hill being reclassified to the 400m Sub-Pedwar category.  The criteria for this sub category being all Welsh hills at or above 400m and below 500m in height that have 20m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.

Y Pedwarau - The 400m Hills of Wales by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Moel Wnog and it is adjoined to the Arenig Fach group of hills, which are situated in the north-westerly part of North Wales (Region A, Sub-Region A2), and it is positioned with a minor road to its west, the A470 road farther to its west, the B4391 road to its south-west and the B4407 road to its south-east, and has the village of Ffestiniog towards the south-west.

When the original 400m height band of Welsh P30 hills was published on Geoff Crowder’s v-g.me website, this hill was not included in the Hills to be surveyed sub list, as it was considered not to meet the criteria then used for this sub category.

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 an estimated c 29 of drop, based on an estimated c 468m summit height and an estimated c 439m bwlch height, with both heights based on interpolation of 10m contouring that appears on the Ordnance Survey 1:25,000 Explorer map. 

Extract from the Ordnance Survey 1:25,000 Explorer map

Prior to the 1^st edition of the Y Pedwarau being published by Europeaklist in May 2013, the details for this hill were re-evaluated and it was listed as a Pedwar with an estimated c 34m of drop, based on the 473m summit spot height that appears on the Harvey 1:40,000 British Mountain Map and an estimated c 439m bwlch height.

However, it was not until 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.

Therefore, the reclassification of this hill to 400m Sub-Pedwar status is due to LIDAR analysis, resulting in a 471.3m summit height and a 441.5m bwlch height, with these values giving this hill 29.8m of drop, which is insufficient for it to be classified as a Pedwar. 

 

The full details for the hill are:

Group:  Arenig Fach 

Name:  Moel Wnog 

OS 1:50,000 map:  124

Summit Height:  471.3m (LIDAR) 

Summit Grid Reference:  SH 73522 44084 (LIDAR) 

Bwlch Height:  441.5m (LIDAR) 

Bwlch Grid Reference:  SH 73597 44355 (LIDAR) 

Drop:  29.8m (LIDAR)

 

For the additions, reclassifications and deletions to Y Pedwarau – The 400m Hills of Wales reported on Mapping Mountains since the May 2013 publication of the list by Europeaklist please consult the following Change Registers:

 

Y Pedwarau

 

Y Pedwarau – 400m Sub-Pedwarau

 

Y Pedwarau – 390m Sub-Pedwarau

 

Y Pedwarau – 390m Double Sub-Pedwarau

 

Myrddyn Phillips and Aled Williams (August 2023)