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)

Mapping Mountains – Trimble Surveys – Glyder Fawr

14.07.16  Moelyci (SH 590 657), Parc Drysgol (SH 589 644) and Moel Rhiwen (SH 581 643)

Parc Drysgol (SH 589 644)

The three hills of Moelyci, Parc Drysgol and Moel Rhiwen make a good circuit from the small community of Rhiwlas, which nestles on their seaward side overlooking the Menai Strait and the expanse of Ynys Môn (Anglesey) beyond.

Having not been on the hills for two months the summer’s greenery struck me as I walked up the narrow lane toward the track which gained the bwlch between Moelyci and Parc Drysgol.  The adjacent hedgerow was overflowing with growth as flowers of all natures sprang out from a multitude of greens, and all highlighted by flashes of sunlight as it gleamed out from the deep grey morning’s sky.

I’d visited these hills once before in May 2004 and remembered them as good hills, the last of the higher Glyderau as their lands descended toward Bangor and Caernarfon, they are last hill bastions and their like usually give excellent views as they look upward to their higher neighbours, but also give perspective downward upon sea and coastline.

Leaving the track I gained height on a good path edged in amongst the upper heathery slopes of Moelyci.  This hill is given four small uppermost 410m ring contours on the Ordnance Survey 1:25,000 map, two close together, the third slightly to their east, whilst the fourth is farther east and beside a cairn.  It is this last easterly point that is given a 410m spot height on the Ordnance Survey 1:50,000 map and therefore listed as the summit in Y Pedwarau, with the hill’s trig pillar marked as being 396m high and positioned on the northerly part of the summit plateau.

Moel Rhiwen (SH 581 643) from high on the slopes of Moelyci

I wanted to survey each high point in turn to determine the hill’s summit position and found the first potential summit to be on rock beside copious amounts of heather.  As the Trimble gathered its customary five minutes of data I looked toward the high Glyderau as a mass of grey swirled around their upper ridges and peaks.  The second point surveyed was close to the first, but this time immersed in heather and therefore I positioned the Trimble on top of my rucksack giving it elevation above the heather and measured a 0.49m offset which will be taken off the processed result.

Gathering data at what turned out to be the high point of Moelyci surveyed with the Trimble GeoXH 6000

The ten figure grid reference for the third point I surveyed did not match the one I had noted for where the next 410m ring contour was on the map, this wasn’t surprising as the lay of land on a hill doesn’t always match that given on the map, with this third position further north on an attractive small rock outcrop and according to the map this didn’t have a separate ring contour.

The third point surveyed on the summit area of Moelyci

The fourth point surveyed was beside a cairn and roughly matched that of the farthest easterly 410m ring contour.  As the Trimble gathered data I stood a safe distance below it and watched as one small figure appeared on the ridge between the points I had previously surveyed.  I wondered who they were and where they were going; their small silhouette pottered across the ridge and then disappeared from view.

Having surveyed all potential high points I gathered the Trimble and retraced my steps back on the slightly wet peaty path to the first point surveyed and dropped down the path toward the connecting bwlch.  I was delayed when I got back onto my inward track by the delights of a number of large juicily tempting bilberries, I only tried a few as I had more surveys to do and a 5.00pm appointment later in the day for an evening walk with Aled, so I didn’t want to linger.

The connecting bwlch to Parc Drysgol was amongst grass and was not hard to determine where its critical point lay.  As the Trimble ebbed down to its 0.1m accuracy level before data should be logged, a Landrover and trailer appeared on the track from the east, the driver stopped, opened the gate and drove into the adjacent field, and we were separated by a high stone wall.  Standing on the bottom of the wall I waved, and as the vehicle drove past I signalled for it to stop and then chatted with the farmer for the next fifteen minutes or so.  We introduced ourselves, Elwyn Jones farmed locally and I asked him about the three hills and their names, he named each one and these match the names that appear on the map.  During this I checked on the Trimble’s downward progress and it still hadn’t reached the 0.1m accuracy level so we continued our chat, I then asked him if he knew any of the farmers from Dyffryn Nantlle, this is where my Mother used to live and where my Brother now lives, he smiled as I mentioned Huw and Olive Jones who were friends with my Mum and who farmed from Tal-y-mignedd, Olive died a few weeks after my Mum, both from the ravages of cancer.  Elwyn continued smiling and told me that Olive was his sister; I smiled back at him and said that I used to sit with her, holding her hand and chatting away during her chemotherapy which coincided with my Mother’s at Ysbyty Gwynedd on the outskirts of Bangor, on occasion tis a small world.

Elwyn Jones

It was good to meet Elwyn and our chance meeting brought back many memories from years gone by, as I packed the Trimble away I headed back to the high wall, asked if I could take a photo of him and put it on my blog, before leaving we shook hands and I smiled back at him as I started the ascent of Parc Drysgol.

The upper part of this hill is covered in heather which gives it a soft feeling, one that adds to its humble 404m map height, I took two data sets on its summit ridge, the second point was visually higher than the first.  As the Trimble gathered data I stood and looked out toward the higher Eryri peaks, many were bathed in low grey murk, but others peered out, their profiles sharp and inviting.

Gathering data at one of two points surveyed for the summit of Parc Drysgol with Moelyci in the background

Moelyci (SH 590 657)

A path led from the summit of Parc Drysgol down toward its connecting bwlch with Moel Rhiwen, once at the bwlch I assessed the lay of land, chose my spot and positioned the Trimble on top of my rucksack for another five minute data set.  Above the bwlch loomed Moel Rhiwen with the profile of three or four horses peering down at me from its higher slopes.

The path leading down to the bwlch continued up toward another stone wall which I clambered over and which gave access to the last bit of uphill to the summit cairn atop Moel Rhiwen.

Gathering data at the summit of Moel Rhiwen

After quickly assessing the land at the summit I judged a point on the western side and at the base of the cairn to be the high point of the hill, and again set the Trimble up on top of my rucksack to give it elevation above its immediate surrounds, this improvised tripod system is now the norm and works well as it is easy to set up and doesn’t require additional equipment to be carried, before leaving I took a second data set from a point a dew metres from the cairn.

All that remained was to retrace my route back toward the last bwlch where a path headed northward out of the heather to the greenery below, as with some walks complication arrives after leaving the hill, and it took me a while to work out where the onward path lay as I was confronted by overgrown fields, old gates, grazing cows and a back garden of a house, and I eventually arrived close to where I had parked my car.

Moelyci from the ruin of Maes Meddygon

All that remained was to retrace my route back toward the last bwlch where a path headed northward out of the heather to the greenery below, as with some walks complication arrives after leaving the hill, and it took me a while to work out where the onward path lay as I was confronted by overgrown fields, old gates, grazing cows and a back garden of a house.  However, as with most walks a way through is usually found and I eventually arrived close to where I had parked my car.

LIDAR summit image of Parc Drysgol (SH 589 644)

Postscript

Since visiting these hills full LIDAR coverage is now available.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height and positional data that is now freely available for England and Wales.  Consequently the numerical details for these hills have been analysed using this technique, resulting in the LIDAR height and position being prioritised for some of these hills.

Survey Result:

Moelyci

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

Summit Grid Reference:  SH 59083 65767 (Trimble GeoXH 6000) (summit relocation)

Bwlch Height:  336.9m (LIDAR)

Bwlch Grid Reference:  SH 59639 63967 (LIDAR)

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

Dominance:  17.79% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

Parc Drysgol

Summit Height:  404.2m (LIDAR)

Summit Grid Reference:  SH 58927 64456 (LIDAR)

Bwlch Height:  342.1m (converted to OSGM15, Trimble GeoXH 6000)

Bwlch Grid Reference:  SH 59094 65303 (Trimble GeoXH 6000)

Drop: 62.1m (LIDAR summit and Trimble GeoXH 6000 bwlch)

Dominance:  15.36% (LIDAR summit and Trimble GeoXH 6000 bwlch)

  

Moel Rhiwen

Summit Height:  401.5m (converted to OSGM15)

Summit Grid Reference:  SH 58141 64300

Bwlch Height:  358.3m (converted to OSGM15)

Bwlch Grid Reference:  SH 58405 64191

Drop:  43.2m

Dominance:  10.76%

For further details please consult the Trimble Survey Spreadsheet.