Wednesday, 12 April 2017

Mapping Mountains – Hill Reclassifications – Y Trichant


Pt. 360.1m (SH 700 466) - Sub-Trichant addition

There has been an addition to the listing of Y Trichant, this is the draft title for the hills in the 300m height band of the Twmpau (thirty welsh metre prominences and upward) due to analysis of LIDAR data by Aled Williams.  The criteria for Y Trichant being all Welsh hills 300m or more and below 400m in height with 30m minimum drop and the now standardised Sub-Trichant being all Welsh hills 300m or more and below 400m in height with 20m or more and below 30m of drop, with this hill being an addition to the Sub-Trichant category.

The hill is a contentious addition to the Sub-Trichant as it is a part of the Llechwedd Slate Mine and may be viewed by some as not being stable in nature and is described as a Tip (disused) on the Ordnance Survey enlarged mapping hosted on the Geograph website.  As is the norm with such places it is not given any ring contours on current Ordnance Survey maps.

The hill is adjoined to the Arenig group with its Cardinal Hill being Manod Mawr (SH 724 446) and is placed in the Region of North Wales (Region A, Sub-Region A3), and it is situated above the town of Blaenau Ffestiniog which is to its south and has the A 470 road to its west.

As this hill is a part of a slate mine that is worked intermittently permission to visit should be sought, because of this no route to its summit is recommended.

The Point (Pt. 360.1m) notation is being used as I do not know an appropriate local or historical name for this hill, and its addition as a Sub-Trichant is due to 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.

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


Pt. 360.1m

Summit Height:  360.1m

Summit Grid Reference:  SH 70068 46618

Bwlch Height:  332.1m

Bwlch Grid Reference:  SH 70214 46655

Drop:  28.0m


Therefore, the 360.1m LIDAR data produced for the summit position at SH 70068 46618 and the 332.1m LIDAR data produced for the bwlch position at SH 70214 46655 gives this hill 28.0m of drop, which is sufficient for its inclusion as a Sub-Trichant, and the listings of Y Trichant and the Twmpau which will be updated accordingly.


The full details for the hill are:

Cardinal Hill:  Manod Mawr

Summit Height:  360.1m (LIDAR data)

Name:  Pt. 360.1m

OS 1:50,000 map:  115

Summit Grid Reference:  SH 70068 46618 
  
Drop:  28.0m (LIDAR data)


Pt. 360.1m (SH 700 466) a new addition to the Sub-Trichant

My thanks to Aled Williams for sending the details of this hill to me.


Myrddyn Phillips (April 2017)

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