Sunday 29 April 2018

Mapping Mountains – Hill Reclassifications – Yr Uchafion


Tap Llwyd (SH 719 065) – Uchaf addition

There has been an addition to the listing of Yr Uchafion due to a survey with the Trimble GeoXH 6000 that was instigated by a previous basic levelling survey (BLS) and summit and bwlch spot heights that appear on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website.  

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 in height that have a minimum drop of 15m, the list is a joint compilation between Myrddyn Phillips and Aled Williams with the introduction to the list being published on Mapping Mountains in November 2015.

Tap Llwyd (SH 719 065)

The name of the hill is Tap Llwyd and prior to the Trimble GeoXH 6000 survey this hill was not classified as it had been surveyed on the 29.09.05 by Myrddyn Phillips using the BLS method as having 44ft 6̋ / 13.6m of drop.  Importantly on this day only the high point of the hill outside of its adjacent conifer plantation could be taken as its summit.  Since the BLS was conducted the Ordnance Survey Interactive Coverage Map hosted on the Geograph website has become available, and this map gives this hill 15m of drop with a 566m summit and 551m bwlch spot height.

Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website

The hill is situated in the Tarennydd group of hills with its Cardinal Hill being Tarren y Gesail (SH 710 058) and is placed in the Region of North Wales (Region A, Sub-Region A3).  The hill is positioned between the A 487 road to its east and the B 4405 road to its west and has the small community of Abergynolwyn towards its west, and has conifer plantations surrounding its western slopes and its lower eastern slopes.

As the designated border of open access land only takes in the open hillside and not the conifer plantation to the hill’s immediate west, permission to visit its summit should be sought, however common sense should prevail and as its high point is only a few metres in to what was felled forestry at the time of the Trimble survey, it is likely there would be no objection to its summit being visited.

Two points were surveyed with the Trimble GeoXH 6000 for summit position, the first being the high point of the hill outside of the forestry and the second being the high point of the hill in what was felled forestry, these surveys came to; 564.7m (converted to OSGM15) and 565.7m (converted to OSGM15) respectively, and with a bwlch height of 550.5m (converted to OSGM15), these values give this hill 15.3m of drop, which is sufficient for it to qualify for Uchaf status.

Gathering data with the Trimble GeoXH 6000 at the summit of Tap Llwyd

The full details for the hill are:

Cardinal Hill:  Tarren y Gesail

Summit Height:  565.7m (converted to OSGM15)

Name:  Tap Llwyd

OS 1:50,000 map:  124

Summit Grid Reference:  SH 71990 06571  
 
Drop:  15.3m (converted to OSGM15)


For the additions, deletions and reclassifications to Yr Uchafion / The Welsh 500m P15s reported on Mapping Mountains please consult the following Change Registers:










For details on the survey that confirmed this hill's addition as an Uchaf

Myrddyn Phillips and Aled Williams (April 2018)


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