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

Lan (SO 052 391) – 400m Sub-Pedwar reclassified to 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 LIDAR analysis initially conducted by Aled Williams and subsequently by Myrddyn Phillips. 

Lan (SO 052 391)

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 from 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 now listed by is Lan, and this was derived from the Tithe map, and it is adjoined to the Mynydd Epynt group of hills, which are situated in the central part of South Wales (Region C2, Sub-Region C2A), and it is positioned with the B4520 road to its west and a minor road to its east, with the A470 road farther to its east, and has the small community of Llaneglwys towards the east south-east.

When the original 400m height band of Welsh P30 hills compiled by Myrddyn Phillips was published on Geoff Crowder’s v-g.me website, this hill was included in the Hills to be surveyed sub list, with a non interpolated c 400m summit height.

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 29m of drop, based on an estimated c 407m summit height and an estimated c 378m bwlch height, with both heights based on 10m contouring that appear on the Ordnance Survey 1:25,000 Explorer map, and these are the details given the hill when the 1^st edition of the Y Pedwarau, now co-authored by Myrddyn Phillips and Aled Williams was published by Europeaklist in May 2013. 

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

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. 

LIDAR image of Lan (SO 052 391)

Therefore, the reclassification of this hill from 400m Sub-Pedwar status is due to LIDAR analysis, resulting in a 413.9m summit height and a 377.2m bwlch height, with these values giving this hill 36.7m of drop, which is sufficient for it to be classified as a Pedwar.

 

The full details for the hill are:

Group:  Mynydd Epynt

Name:  Lan

OS 1:50,000 map:  160

Summit Height:  413.9m (LIDAR)

Summit Grid Reference:  SO 05239 39141 (LIDAR)

Bwlch Height:  377.2m (LIDAR)

Bwlch Grid Reference:  SO 04853 39386 (LIDAR)   

Drop:  36.7m (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 (December 2016)