Mapping Mountains – Hill Reclassifications – Y Pedwarau

Lan (SN 952 552) – 390m Sub-Pedwar deletion

There has been a deletion to the listing of Y Pedwarau due to analysis of LIDAR data by Aled Williams.  Y Pedwarau is the title for the list of 400m hills of Wales and takes in all Welsh hills at or above 400m and below 500m in height that have a minimum 30m of drop, the list is a joint compilation between Myrddyn Phillips and Aled Williams and it commenced publication on Mapping Mountains on the 30.01.17.

LIDAR image of Lan (SN 952 552)

Accompanying the main Y Pedwarau list are five categories of sub hills, with this hill being deleted from the 390m Sub-Pedwar category.  The criteria for 390m Sub-Pedwar status being all Welsh hills at or above 390m and below 400m in height that have a minimum 30m of drop.

Prior to analysis of LIDAR data the hill was listed with 76m of drop based on the 390m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and the 314m bwlch spot height that appears on the Ordnance Survey enlarged mapping hosted on the Geograph website.

The hill is situated in the Elenydd range with its Cardinal Hill being Gorllwyn (SN 917 590) and is placed in the Region of Mid and West Wales (Region B, Sub-Region B2), the hill is positioned between the small communities of Llanafan Fawr to the east north-east and Glandulas towards the south.

As the hill is not a part of designated open access land permission to visit should be sought, if permission is granted there are public footpaths that approach the hill from the north, west and south.

The name the hill is listed by is Lan and this was derived from the Tithe map, and its deletion from 390m Sub-Pedwar status is due to the analysis of LIDAR data by Aled Williams.  LIDAR (Light Detection & Ranging) is highly accurate height data that is now freely available for much of England and Wales.

LIDAR analysis gives the hill the following details:

Lan

Summit Height:  389.4m

Summit Grid Reference:  SN 95203 55201

Bwlch Height:  314.4m

Bwlch Grid Reference:  SN 95556 55887

Drop:  74.9m

Therefore, the 389.4m LIDAR data produced for the summit position at SN 95203 55201 and the 314.4m LIDAR data produced for the bwlch position at SN 95556 55887 gives this hill 74.9m of drop and with its summit height being below 390m it is insufficient for its continued inclusion as a 390m Sub-Pedwar.

The full details for the hill are:

Cardinal Hill:  Gorllwyn

Summit Height:  389.4m (LIDAR)

Name:  Lan

OS 1:50,000 map:  147

Summit Grid Reference:  SN 95203 55201

Drop:  74.9m (LIDAR)

The total for Y Pedwarau remains at 442 hills with nine additions, and fourteen reclassifications to 400m Sub-Pedwar status since publication of the list by Europeaklist in May 2013.

The total for the 390m Sub-Pedwarau decreases by one to 37 hills and the total for the 390m Double Sub-Pedwarau remains at 26 hills.

The list of Pedwar hills is available from the Haroldstreet website (January 2014) with all subsequent changes detailed on the Mapping Mountains site, with the list also having commenced publication on Mapping Mountains on the 30.01.17.

For the additions, reclassifications and deletions to Y Pedwarau 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 (July 2017)