Wednesday, 4 January 2017

Mapping Mountains – Hill Reclassifications – Yr Uchafion


Cwar yr Ystrad (SO 084 142) - Uchaf addition

There has been a new addition to the listing of Yr Uchafion due to analysis of LIDAR data by Aled Williams with a subsequent Trimble GeoXH 6000 surveyYr 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 Cymoedd Gwent group of hills 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.

Contemporary 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 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.

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:  559.0m

Bwlch Grid Reference:  SO 08376 14189

Drop:  21.1m


The subsequent Trimble GeoXH 6000 survey produced a summit height of 579.3m and a bwlch height of 558.8m, with these values giving this hill 20.5m of drop, which is sufficient for this hill to be classified as an Uchaf.

This now revises the total in Yr Uchafion which will be updated accordingly.


The full details for the hill are:

Cardinal Hill:  Pen y Fan

Summit Height:  579.3m (converted to OSGN15)

Name:  Cwar yr Ystrad

OS 1:50,000 map:  160

Summit Grid Reference:  SO 08445 14278  
  
Drop:  20.5m

Cwar yr Ystrad (SO 084 142)

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


UCHAF ADDITIONS



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




UCHAF RECLASSIFICATIONS







UCHAF DELETIONS





Myrddyn Phillips and Aled Williams (January 2017)



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