Mapping Mountains – Summit Relocations – Y Pedwarau – The 400m Hills of Wales

Panylau Gwynion (SH 935 063) 

There has been a Summit Relocation to a hill that is listed in the Y Pedwarau – The 400m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail on contemporary maps produced from Ordnance Survey data and a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips and Aled Williams. 

Panylau Gwynion (SH 935 063)

The criteria for the list that this summit relocation applies to are:

Y Pedwarau – The 400m Hills of Wales.  Welsh hills at or above 400m and below 500m in height that have 30m minimum drop, the list is co-authored by Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.

Y Pedwarau - The 400m Hills of Wales by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Panylau Gwynion and it is adjoined to the Carnedd Wen group of hills, which are situated in the southern part of North Wales (Region A, Sub-Region A3), and it is positioned with the A470 road to its south-west and a minor road to its south-east, and has the village of Talerddig towards the south.

When the 1^st edition of the Y Pedwarau was published by Europeaklist in May 2013, this hill was listed with 39m of drop, based on the 451m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map at SH 93575 06311 and a 412m bwlch spot height that appeared on the Ordnance Survey Vector Map Local that was hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

Extract from the Ordnance Survey 1:25,000 Explorer map

The upper part of this hill has two 450m map ring contours.  The 451m map spot height appears in a relatively large 450m contour that until recent times was a part of a conifer plantation, whilst just to the west of the plantation’s boundary fence was a small 450m map ring contour on open ground that logs on the Hill Bagging website reported as a knoll and which could be higher. 

The Trimble GeoXH 6000 gathering data from the lower deforested top with the higher summit of Panylau Gwynion in the background

The Trimble GeoXH 6000 gathering data at the heathery knoll summit of Panylau Gwynion with the lower deforested top in the background

However, it was not until the Trimble GeoXH 6000 survey that the details for this hill could be accurately re-assessed.  The summit height and position produced by the Trimble GeoXH 6000 survey is 450.3m positioned at SH 93557 06357, as opposed to 449.1m positioned at SH 93575 06303 to the high point of what used to be within the conifer plantation, and this position in relation to that previously given comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies when the high point of the hill is found to be positioned; in a different field, to a different feature such as in a conifer plantation,  within a different map contour, to a different point where a number of potential summit positions are within close proximity, when natural ground or the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary or covered reservoir that is judged to be a relatively recent man-made construct, or a relocation of approximately 100 metres or more in distance from either the position of a map spot height or from where the summit of the hill was previously thought to exist.

Therefore, the summit height produced by the Trimble GeoXH 6000 survey is 450.3m and this is positioned at SH 93557 06357, this position is not given a spot height on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, and is approximately 55 metres south south-eastward from where the previously listed summit is positioned.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Carnedd Wen

Name:  Panylau Gwynion

OS 1:50,000 map:  125

Summit Height:  450.3m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference (New Position):  SH 93557 06357 (Trimble GeoXH 6000)  

Bwlch Height:  412m (spot height)

Bwlch Grid Reference:  SH 93627 06715 (spot height)

Drop:  38m (Trimble GeoXH 6000 summit and spot height bwlch)

 

Myrddyn Phillips and Aled Williams (September 2022)