Wednesday, 4 January 2017

Mapping Mountains – Hill Reclassifications – Yr Uchafion

Cwar yr Ystrad (SO 083 142) - Uchaf addition

There has been a new addition to the listing of Yr Uchafion instigated from analysis of LIDAR data by Aled Williams.  Yr Uchafion is the draft title for a list of the Welsh 500m P15s that takes in all hills in Wales at or above 500m that have a minimum drop of 15m, the list is a joint compilation with Aled Williams.  Details relating to this list were published on the Mapping Mountains site in November 2015.

The hill is situated in the southern part of the Bannau Brycheiniog (Brecon Beacons) group of hills with its Cardinal Hill being Pen y Fan (SO 012 215) and is placed in the Region of South Wales (C-2).  As its name suggests the hill is a part of a quarry with its qualification as an Uchaf partly due to past quarry activities, it is situated between the Pentwyn and Pontsticill Reservoirs to its west and the Talybont Reservoir to its north north-east, with the town of Merthyr Tudful to its south south-west and the small community of Trefil to its east south-east.

Current Ordnance Survey 1:50,000 and 1:25,000 mapping does not give this hill any ring contours, as is the norm for areas of land that have been quarried.  The hill is of interest as it is only now listed as an Uchaf through the quarrying activities of past years that has resulted in producing a new bwlch for the hill.

The hill can be accessed from a number of directions on public footpaths including from its south-west and from its north, whilst the route from the paved road north of Trefil also gives access onto the quarry track, but if wishing to ascend from this direction it should be noted that there is a barrier across the road beyond Trefil that is locked at 5.00pm and unlocked at 6.30am with online write ups stating this barrier is locked at weekends.

The name of the hill is Cwar yr Ystrad and its inclusion as an Uchaf is due to the analysis of LIDAR data by Aled.  LIDAR (Light Detection & Ranging) is highly accurate height data that is now freely available for much of England and Wales, and as mentioned in the first paragraph of this post; if Cwar yr Ystrad has a minimum drop of 15m it would be included in the listing of Welsh hills at or over 500m in height that has a minimum of 15m of drop, and has the working title of Yr Uchafion.

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

Cwar yr Ystrad

Summit Height:  579.9m

Summit Grid Reference:  SO 08358 14245

Bwlch Height:  558.9m

Bwlch Grid Reference:  SO 08376 14189

Drop:  21.0m

Therefore, the 579.9m LIDAR data produced for the summit position at SO 08358 14245 and the 558.9m LIDAR data produced for the bwlch position at SO 08376 14189 is sufficient for this hill to be classified as an Uchaf with 21.0m of drop.

This now revises the total in Yr Uchafion which will be updated accordingly and the hill is now listed as an Uchaf.

The full details for the hill are:

Cardinal Hill:  Pen y Fan

Summit Height:  579.9m (LIDAR data)

Name:  Cwar yr Ystrad

OS 1:50,000 map:  160

Summit Grid Reference:  SO 08358 14245 
Drop:  21.0m (LIDAR data)

The reclassifications to Yr Uchafion / The Welsh 500m P15s reported on Mapping Mountains are ills of wales as follows:


Cwar yr Ystrad (LIDAR data) (SO 083 142) added as an Uchaf with 21.0m of drop.



Myrddyn Phillips and Aled Williams (January 2017)

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