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

Moelyci (SH 590 657)

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 a Trimble GeoXH 6000 summit survey and LIDAR bwlch analysis conducted by Myrddyn Phillips.

Moelyci (SH 590 657)

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, accompanying the main list are five categories of sub hills; 500m Sub-Pedwarau, 500m Double Sub-Pedwarau, 400m Sub-Pedwarau, 390m Sub-Pedwarau and the 390m Double Sub-Pedwarau.  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 Moelyci, and it is adjoined to the Glyder Fawr group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned with minor roads to its north, west and south-east, and the B4244 road to its north-west, and has the small community of Rhiwlas towards its west .

When the 400m height band of Welsh P30 hills were published on Geoff Crowders v-g.me website, this hill was listed with a non-interpolated c 410m summit height, with an accompanying note stating; Four points of same height.  This note references the small contour rings that appear on the Ordnance Survey 1:25,000 Explorer map.

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

When the Y Pedwarau booklet was published by Europeaklist in May 2013, the details for this hill were reassessed and its summit height listed as 410m, based on the spot height positioned at SH 59379 65943 that appears on the Ordnance Survey 1:50,000 Landranger map.

Extract from the Ordnance Survey 1:50,000 Landranger map

However, it was not until the survey with the Trimble GeoXH 6000 that the summit details for this hill could be accurately re-assessed.  The grid reference for each contour was noted and the intention was to survey each in turn to ascertain the high point of the hill.  However, sometimes contours do not match what appears on the ground and therefore the ground where one ring contour appears was visually judged lower and was not surveyed, whilst another point not given a 410m ring contour on Ordnance Survey maps was judged to warrant a survey.  The results of the four surveys appear below:

1^st survey:  409.9m (409.864m, converted to OSGM15) at SH 59083 65767

2^nd survey:  409.5m (409.527m, converted to OSGM15)) at SH 59086 65786

3^rd survey:  409.4m (409.415m, converted to OSGM15) at SH 59104 65898

4^th survey:  409.5m (409.486m, converted to OSGM15) at SH 59375 65941

The position of the fourth 410m ring contour that was not surveyed is at SH 59167 65790

The height produced by the Trimble GeoXH 6000 to the summit of this hill is 409.9m and this is positioned at SH 59083 65767, and this 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 either on Ordnance Survey maps or interactive mapping, 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 considered 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.

The Trimble GeoXH 6000 gathering data at the summit of Moelyci, with the old position of the summit in the background on the left of this photograph

Therefore, the height produced by the Trimble GeoXH 6000 to the summit of this hill is 409.9m and is positioned at SH 59083 65767, 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 295 metres west south-westward from where the previously listed summit is positioned. 

The full details for the hill are:

Group:  Glyder Fawr

Name:  Moelyci

OS 1:50,000 map:  114, 115

Summit Height:  409.9m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference (New Position):  SH 59083 65767 (Trimble GeoXH 6000) 

 

Bwlch Height:  336.9m (LIDAR)

Bwlch Grid Reference:  SH 59639 63967 (LIDAR)

Drop:  72.9m (Trimble GeoXH 6000 summit and LIDAR bwlch) 

Myrddyn Phillips and Aled Williams (July 2016)