Mapping Mountains – Hill Reclassifications – Marilyns

 

Rhinog Fach (SH 664 270) – Submarilyn reclassified to Marilyn

This is one in a series of retrospective Hill Reclassification posts that detail hills whose status has altered in the listing of the Welsh Marilyns.  These reclassification posts will give details of hills where I have had direct association with their change of status, and they will tie in with a Change Register giving detail to this list and its alterations since publication in the TACit Tables booklet. 

The listing of Welsh Marilyns was published in booklet format by TACit Tables in February 1997 and entitled The Hewitts and Marilyns of Wales.  The Marilyns were originally listed as an all British compilation and were published by Cicerone Press in 1992 in the book entitled The Relative Hills of Britain.  The list compiler for the Marilyns is Alan Dawson. 

When the Welsh Marilyns list was published in booklet format there were 156 qualifying hills with a further 27 Welsh Submarilyns also included.  The criteria for Marilyn status being any hill that has a drop of at least 150m, irrespective of their height, with the criteria for Submarilyn being any hill that has 140m or more and below 150m of drop. 

The Hewitts and Marilyns of Wales by Alan Dawson

The details for the hill reclassification appear below: 

The name of the hill is Rhinog Fach, and it is situated in the Rhinogydd group of hills in the north-western part of Wales, and is positioned with the coast and the A496 road to its west and the A470 road to its east, and has the village of Trawsfynydd towards the north north-east and the town of Abermaw (Barmouth) towards the south south-west. 

Prior to this hill’s reclassification to Marilyn status it was listed as a Submarilyn with an estimated c 148m of drop, based on the 712m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated bwlch height of c 564m. 

The Trimble GeoXH 6000 gathering data at the summit of Rhinog Fach

As its estimated c 148m listed drop was near the benchmark value of 150m it was prioritised for a GNSS survey and this took place on the 24^th August 2021.  The summit and bwlch of this hill were surveyed by Myrddyn Phillips using a Trimble GeoXH 6000, with two summit and three bwlch data sets taken, resulting in a 711.6m summit height and a 560.6m bwlch height, with these values giving this hill 151.0m of drop. 

The Trimble GeoXH 6000 gathering data at the bwlch of Rhinog Fach

These details were forwarded via email to the list author of the Marilyns in the evening of the 26^th August 2021, and notification received from Alan Dawson via email in the early hours of the 27^th August 2021 of his acceptance of this hill’s reclassification to Marilyn status. 

 

The full details for the hill are: 

Name:  Rhinog Fach 

OS 1:50,000 map:  124

OS 1:25,000 map:  18

Summit Height:  711.6m (converted to OSGM15) 

Summit Grid Reference:  SH 66485 27017 

Bwlch Height:  560.6m (converted to OSGM15) 

Bwlch Grid Reference:  SH 66561 26533 

Drop:  151.0m 

 

Myrddyn Phillips (November 2021)

 

 

 

 

 

 

 

Rhinog Fach – reclassification to Marilyn status

 

UKHillwalking Article 

UKHillwalking recently published an article on the survey that reclassified Rhinog Fach to Marilyn status.  The original article and a link to it on the UKHillwalking website appear below. 

 

New Welsh Marilyn 'Discovered' - and it's a good one

Rhinog Fach has been added to the list of Marilyns, following a re-survey of its relative prominence. The peak, arguably the most impressive in the Rhinogydd, is a major addition to the list of (now) 1556 summits.

Rhinog Fach and Llyn Hywel

A Marilyn is any hill in Britain that has a minimum drop of 150m, irrespective of its overall height. Authored by Alan Dawson, the list was originally published by Cicerone Press in 1992 in the book The Relative Hills of Britain, and has become a popular objective for ambitious baggers.

Avid hill surveyor Myrddyn Phillips established Rhinog Fach’s Marilyn status on Friday 27th August, having established the height of the summit and the col below, and announced the finding in his blog Mapping Mountainbs.

"Rhinog Fach has been on the prioritised survey list for a number of years as Alan Dawson had listed it as a high prominence Submarilyn with an estimated c 147m of drop in his Hewitts and Marilyns of Wales booklet published by TACit Tables" says Myrddyn.

"I had an email exchange with Alan about surveying this hill soon after getting my Trimble [survey equipment] in late 2013 and I then promised to survey it as soon as possible. It's only taken me another eight years to do so!"

As Marilyn status depends on a minimum 150m of drop, and as drop is dependent upon the summit and connecting col height, both summit and col needed to be surveyed. 

"I operate a piece of equipment named the Trimble GeoXH 6000, this gives highly accurate height and positional data" explains Myrddyn.

The Trimble set up on the summit of Rhinog Fach

"The Trimble operates in a similar way to a SatNav and gathers signals from orbiting satellites. Once gathered, the resulting data is processed against Rinex Data available via the Ordnance Survey website.

One of three data sets taken at the bwlch area of Rhinog Fach

"For Rhinog Fach determining the very highest point of the hill was easy as it consists of a protruding rock positioned about 2 metres from the base of the summit cairn. As the Trimble has an internal antenna it can gather data aligned to the high point without the need for a pole, tripod and external antenna. 

"I took two data sets at the summit, one with the Trimble positioned aligned with the high point and one with the Trimble placed on my rucksack which acts as an improvised tripod, with the measurement offset duly noted. This would give comparison of height; in this instance just 0.01m difference.

"Three data sets were taken from the area of the connecting col, the 1st and 2nd on the hill to hill traverse (low point of these signifies the important data set) and the 3rd on the valley to valley traverse.  The high point of the 3rd compared to the important one of the 1st and the 2nd surveys signifies the all-important col position. This can get a little complicated on occasion, and when conditions are extremely warm and a multitude of surveys are being taken it even baffles me sometimes!"

Evening light on Rhinog Fach

As one of the more impressive peaks in Wales, Rhinog Fach counts as a major addition to the Marilyns. But thanks to their prominence, even less distinctive entries on the list have their attractions, according to Myrddyn:

"One of the joys of the Marilyns is the variety of hills included in the list" he says, "with many of the giants as well as many lower heighted hills qualifying. All of them are relatively prominent and therefore all should, on a good clear day, give extensive views. The last new Welsh Marilyn, Mynydd Anelog (SH 151 272),  is only 191.4m high but is positioned toward the end of Pen Llŷn giving beautiful coastal views out toward another Marilyn on Ynys Enlli." 

Alan Dawson has now confirmed Rhinog Fach as a new Marilyn, the first in Wales since the survey of Mynydd Anelog in July 2013, and the first in Britain since the survey of Beinn Dearg by Jon Metcalf in 2018.

There's still a slim chance that new entries to the list will be uncovered, Dawson thinks:

"Rhinog Fach has been in need of a survey for many years and it is great news that Myrddyn has done it and made this discovery" he told us.

"The only other realistic possibility for a new Marilyn is Faan Hill on Shetland Mainland, a mere 173m high. That will not be an easy one to survey. Meall an t-Suidhe next to Ben Nevis is estimated to have 147m drop and so it also has a small chance of reaching 150m. There is also the possibility of summits being relocated, as happened recently when Lidar data showed that White Hill near Dumfries was higher than nearby Hightown Hill, though OS maps show it to be a metre lower."

 

For the original article published on the UKHillwalking website

Rhinog Fach – reclassification to Marilyn status

 

Grough Article 

Grough recently published an article on the survey that reclassified Rhinog Fach to Marilyn status.  The original article and a link to it on the Grough website appear below. 

 

Surveying sleuth Myrddyn Phillips adds a new Marilyn to hill-baggers' list

Myrddyn Phillips, Guest contributor

Monday 30 August 2021 12:13 AM GMT

 

To non-hill-list baggers, the Marilyns can seem a strange group.

Conceived from a homonymous linking of Sir Hugh Munro’s list of Scottish 3,000-footers and the stage surname of glamorous actor Norma Jean Mortenson, the Marilyns don’t even need to soar too high.

Rhinog Fach, Britain's newest Marilyn

There’s no minimum altitude needed for a hill to join the club, just the necessity of the peak protruding by 150m (492ft) from the surrounding land, or sea.

The Marilyns list was devised by Alan Dawson and detailed in his book The Relative Hills of Britain, ranging from the UK’s highest peak Ben Nevis to Crogearraidh na Thobha on North Uist, which is only just over 500ft high.

A complete round of the marilyns is no mean feat, as the list includes remote sea stacks in the St Kilda archipelago.

But seasoned hill sleuths have their eye on the list with a view to adding to it.

Myrddyn Phillips is one such man. He set out in his native Welsh hills in the search for a new Marilyn. Here’s his account of the latest discovery.

 

The Marilyns burst upon the hill-listing scene almost 30 years ago with a qualifying criterion that tore up the norm of minimum height and minimum drop and used just one defining definition: minimum drop. This simple one-pronged use of qualification revolutionised how many people view what a worthy and interesting hill can be.

Over subsequent years the list has become well established with many dedicated followers slowly working their way through what was the current total of 1,555 British hills, all of which have a minimum 150m of drop.

With two St Kilda sea stacks to tackle, the marilyns are one of the most sought-after lists. It was not until 13 October 2014 that Rob Woodall, closely followed by Eddie Dealtry, climbed Stac Lee, their final Marilyn. Since then another nine people have climbed all the Marilyns.

Gathering data at the summit of Rhinog Fach

Recent years have seen a great swathe of surveying activity scrutinising the list and concentrating on those marginal hills, the ones close to or just over that all-important 150m of drop mark. This has resulted in a number of additions since first publication; however these additions are now becoming a rarity as more hills are accurately surveyed and their drop values confirmed.

The last new Marilyn entered the list three years ago when Jon Metcalf surveyed Beinn Dearg (NC 279 658) as having 150.7m of drop. The last new Welsh Marilyn entered the list eight years ago, this was Mynydd Anelog (SH 151 272) with 151.0m of drop.

Well, guess what, Wales has another new Marilyn, its first since 2013!

The hill is Rhinog Fach (SH 664 270) which is positioned in west Wales, with the town of Barmouth to its south and the village of Trawsfynydd to its north. The hill forms part of the northern Rhinogydd, one of the toughest, but also one of the most rewarding mountain landscapes anywhere in the country.

Rhinog Fach was surveyed on 24 August using a Trimble GeoXH 6000, a piece of equipment that gives highly accurate results both in height and position and which has been responsible for a number of status changes to hills over recent years, but never for a Marilyn.

Two data sets were taken at the summit, one on the ground with the equipment’s internal antenna aligned to the high point with the end of the Trimble placed on a rock taken from the cairn to give it horizontal alignment, and the second atop my rucksack with the measurement offset duly noted.

At the col with the Trimble GeoXH 6000 gathering one of its data sets

For such surveys every centimetre can be vital, so for those of a numerical mind the all-important figures appear below:

 

Rhinog Fach summit:

711.632m at SH 66485 27017 – Trimble on ground

711.642m at SH 66485 27017 – Trimble on rucksack

Average: 711.637m.

 

Three data sets were taken from the area of the bwlch, which is positioned just to the east of the solid stone wall traversing these hills. The ground on the west side of the wall and ground at the base on its eastern side is lower compared to where the Trimble was set-up.

 

Rhinog Fach bwlch:

560.618m at SH 66555 26531 – hill to hill traverse

560.560m at SH 66557 26533 – hill to hill traverse

560.599m at SH 66561 26533 – valley to valley traverse, and what turned out to also be the hill-to-hill traverse.

 

These values give Rhinog Fach 151.038m of drop.

Once data were processed I notified Alan Dawson who has kindly submitted the following:

“Rhinog Fach has been in need of a survey for many years and it is great news that Myrddyn has done it and made this discovery.

“The only other realistic possibility for a new Marilyn is Faan Hill on Shetland Mainland, a mere 173m high. That will not be an easy one to survey.

Rhinog Fach and Llyn Hywel

“Meall an t-Suidhe next to Ben Nevis is estimated to have 147m drop and so it also has a small chance of reaching 150m. There is also the possibility of summits being relocated, as happened recently when Lidar data showed that White Hill near Dumfries was higher than nearby Hightown Hill, though OS maps show it to be a metre lower.”

This now brings the overall total of British Marilyns to 1,556.

For the original article published on the Grough website

 

Mapping Mountains – Trimble Surveys – Y Llethr

 

24.08.21  Rhinog Fawr (SH 656 290, only bwlch surveyed), Rhinog Fach (SH 664 270) and Pt. 558.3m (SN 661 267) 

Rhinog Fach (SH 664 270)

There are many upland areas in Wales that captivate me and draw me back time and again.  The trackways of the Radnorshire hills on a bright and crisp spring morning with skylarks singing overhead or the tranquil surrounds of the open Elenydd in autumn, but few can compare to the quality of the northern Rhinogydd, these hills are rugged and unforgiving and form a barrier between the land to their east and the coastal plain to their west. 

For many years my walking was dominated by the Welsh 2,000ft hills with many repeated ascents, nowadays it is mainly on lower heighted hills, and to an extent is led by my surveying.  However, when opportunity arises to visit those higher 2,000ft’s it is one not to miss. 

Today I wanted to visit a hill I had been up on 18 previous occasions and one that was long overdue an accurate survey.  The hill is Rhinog Fach which is positioned in the northern Rhinogydd. 

Rhinog Fach is currently listed with an estimated c 148m of drop, just a tantalising 2m short of the 150m drop criterion for Marilyn status.  Over recent years Alan Dawson; the hill list compiler of the Marilyns and author of the Relative Hills of Britain book, has surveyed many hills marginal to the 150m drop criterion.  The majority of these hills are in Scotland, but there is one hill in Wales that also requires an accurate survey to determine its drop value and status, and that hill is Rhinog Fach. 

With a high pressure system centred over the country giving relatively dry conditions, albeit with drizzly morning’s around the eastern part of Mid Wales, and with a forecast of west is best and lots of sun symbols on the Trawsfynydd Met Office web page, I headed toward Coed y Brenin to park at the end of a narrow paved road that heads west from the busy A470.  I knew even before seeing the Rhinogydd that their higher tops would be immersed in morning clag, as the tops of all other hills heading west from Welshpool were cloaked in cloud.  However, I was in no rush and leaving my car I proceeded to slowly make my way through the undergrowth constituting the public footpath toward Graigddu-isaf, an old farm house that is now an Airbnb let. 

The old farmhouse is positioned in a small clearing with the forest track leading past it; I was soon on it walking along the forest track heading south.  Overhead the sky was grey with a constant cloud blanket that stretched the full width of Wales.  But I knew as time progressed the cloud would rise and if the same weather condition were applicable to this part of Wales, as to Welshpool, the sun would break through by early afternoon. 

I lazily plodded up the continuation of the forest track, eventually emerging at a sign that pointed confidently toward Bwlch Drws Ardudwy.  At this junction the conifer infestation had been felled giving an unobstructed view of the two Rhinog hills; Fawr and Fach; both heading skyward in to the morning murk. 

The way to the bwlch with Rhinog Fach enshrouded in early morning clag

A gravelled path led from the junction up to a gate and the continuation of a path on to the open hillside.  It was good to be back here, although this was a route I had used in the past, my favoured route of ascent for Rhinog Fach is from the west via Cwm Nantcol, this gives an open view of the hills from a beautiful high valley, but the forest route has a higher start and is much easier to get to when driving in from the east. 

My first planned survey of the day was the bwlch of Rhinog Fawr and as I walked up the path heading toward it, the open nature of the hillside quickly closed in, with the boulder strewn slopes of Rhinog Fawr rising upward on my right and the steep slopes of Rhinog Fach doing likewise on my left.  It was a humbling place to find myself. 

The steep path leading up Rhing Fach from Bwlch Drws Ardudwy

The bwlch position for Rhinog Fawr was relatively easy to pinpoint and soon the Trimble was set up atop my rucksack, the measurement offset between its internal antenna and the ground at its base noted and once the 0.1m accuracy level was attained before data should be logged, I set it to gather data and sat behind a rock to wait the allotted five minutes. 

Gathering data at the bwlch of Rhinog Fawr

Once the first data set of the day was gathered and stored, I packed the Trimble away and peered up at the horrendously steep slope I had somehow voluntarily chosen as my ascent route.  This route is uncompromising and just heads up through heather and rock.  It looked intimidating. 

The cloud base was still relatively low and would remain so for another 90 minutes, therefore I was in no rush and with the steep slope immediately in front of me I made slow, but steady progress up it.  I rested frequently and looked out east where the cloud still hung to all high hills.  Behind me the cloud danced on the upper section of Rhinog Fawr with the brisk breeze whisking it across the summit rocks. 

Eventually the steepest section of the ascent was behind me and cresting a rise the upper part of the hill bulged up in front.  This resembles a cone of a hill seemingly plonked on top of what is already quite a substantial land mass, thankfully by the time I was looking up at this scene the cloud base was slowly edging ever higher and the route ahead was clear. 

The path eventually crests the northern ridge of Rhinog Fach, at this point I had just walked up in to the mist which was being skimmed across the hill by a strengthening breeze, so much so that I contemplated stopping to put on my one skin jacket as my arms were getting quickly chilled, I persevered without and continued following the path toward the summit of the hill. 

The summit of Rhinog Fach consists of a small protruding rock about 2 metres from the base of an untidy cairn.  I quickly set the Trimble up aligned with the highest part of the rock and set it to gather data.  I was thankful that the summit was easy to identify as I wondered if I would have to take a number of data sets from various points surrounding it.  But to compare survey results I wanted to gather a second data set with the Trimble now positioned over the highest rock and on my rucksack.  As I was setting the equipment up I was joined by two walkers, one from Llanelli and the other from Caerffili who were bagging hills around the Rhinogydd for a few days based in Maentwrog.  As the Trimble gathered the second summit data set we sat below the equipment chatting about the hills. 

Gathering data at the summit of Rhinog Fach

To have wanted to survey this hill for many years and many other surveys seemingly always getting in the way, and now to finally be here on its summit with the Trimble quietly beeping away gathering individual datum points, was both a relief and a joy.  As I sat glimmers of sunshine fed across the land toward the coast to the west.  It felt like being on top of the world, perched on this boulder strewn hill, sitting on a rock looking out at an ever evolving view.  As I turned to close the Trimble down I suddenly realised that the cloud base was now above the summit, which boded well for the remainder of the walk. 

I walked part of the way down toward the connecting bwlch in the company of the two walkers from south Wales, but as I opted for my normal descent route on the western side of the stone wall, they reversed their inward route on its eastern side.  We met again down on leveller ground and walked to the bwlch together.  They still had a long day ahead with Y Llethr, Diffwys and a walk back in to Cwm Nantcol ahead, whilst I now concentrated on the bwlch adjoined to Rhinog Fach. 

Y Llethr rising above Llyn Hywel

I was surprised to find that ground on the eastern side of the stone wall that crosses the bwlch was higher than on its western side, imagining that the wall would cross the actual bwlch.  Therefore I concentrated my efforts on a small area of land just to the east of the stone wall, taking three data sets in all, two on the hill to hill traverse and one on the valley to valley traverse. 

I was at the bwlch for over 40 minutes and watched the two South Walian walkers crest the upper part of Y Llethr and disappear from view.  By now the full extent of Rhinog Fach was on view and would remain so for the remainder of the walk. 

Gathering the first of three data sets on the area of the bwlch

Happy with my efforts at the bwlch I packed the Trimble away, scrambled back over the wall and walked a short distance back toward Rhinog Fach to connect with the path leading down to the northern shore of Llyn Hywel, which I’ve heard by many to be the most beautiful mountain lake in Wales, I would not argue otherwise. 

The path led to the outflow of the lake, I now wanted to survey the small prominence hill that overlooks Llyn Hywel from the lake’s western edge and therefore followed the continuation of the path around the western shore, only leaving it to head up toward the connecting bwlch of the hill.  This bwlch was typical northern Rhinogydd country as it has large boulders strewn around it, many amongst reed grassed tussocks.  I soon picked my preferred spot and soon the Trimble was gathering its seventh data set of the day. 

Gathering data at the bwlch of Pt. 558.3m

Once the Trimble was closed down and packed away I followed a narrow path leading toward the summit, which is crowned by a flattish outcrop of rock.  By now the breeze was blowing across the lake and therefore I placed the Trimble on the ground aligned with the highest part of the summit rock.  During data collection the sun finally broke through as the cloud that had lingered all day began to break, and this gave me wonderful colour for the remainder of the walk. 

Gathering data at the summit of Pt. 558.3m (SH 661 267)

All that remained was to follow paths back to the forest track.  I took my time and enjoyed the wonderful mountain scenery with Rhinog Fawr looking a beast of hill from this perspective.  Its profile a great lump of rock and heather, from this vantage point Rhinog Fawr must be one of the most impressive hills that Wales has to offer.  I savoured this view, as I did when I left the shore of Llyn Hywel, it had been 16 years since I last stood on the summit of Rhinog Fach and it is now reaching a point that when on a higher hill I wonder if I will ever return.  The afternoon sunshine, with the purple of heather and the rusted tips of reed grass just starting to turn and that stunning profile of Rhinog Fawr was to be remembered and if this is the last time I venture to this particular domain, it gave me a fine memory to implant in my mind’s eye, one that will remain with me for a long time to come. 

The route back toward Llyn Hywel with Y Llethr in the background

The mountain goats of the northern Rhinogydd

Leaving the outflow of Llyn Hywel I connected with the good path leading down in to Cwm Nantcol, on the way I met two backpackers heading up to the lake to overnight.  They were from Cardiff and we stopped and chatted for ten minutes or so.  I enjoy meeting people when on the hill and the conversation that ensues, this time it also gave me a rest as my energy levels were beginning to plummet.  A little lower I met a man from Manchester who was doing the full traverse of the Rhinogydd, his father lived in Harlech and was picking him up in Barmouth later in the evening, he still had a long way to go. 

Rhinog Fawr with Llyn Cwmhosan in the foreground

Arriving in the upper reaches of Cwm Nantcol was a blessing as my knees no longer had any steep descent to contend with.  However, it also meant that I now had to veer right and reclaim lost height to crest the upper part of Bwlch Drws Ardudwy, this I found a struggle and stopped an inordinate amount of time to recover my breath.  My energy levels had completely plummeted; I sat frequently, ate a banana and a club biscuit and struggled on, eventually reaching a prominent cairn signifying the top of the path overlooking the bwlch. 

The wall leading to Bwlch Drws Ardudwy

Before leaving the bwlch I peered up at that horrendously steep slope I had tackled earlier in the morning, leading toward the summit of Rhinog Fach.  I will probably never have the misfortune to head up it again.  I found this a comforting thought. 

I slowly continued on the path leading back to the felled section of forestry and the gravelled path leading down to the junction with the forest track.  On the way I watched a multitude of butterflies feeding on buddleia plants, which added their light purples to the bloom of heather and the red berries of the rowan.  I stopped to watch and take a few photographs and looked back toward the hill, now free of clag and bathed in late afternoon sunshine. 

Jen, Rog and Archie Lewins

The forest track gave an easy way back to my car, and one that was to get easier as when I approached the forest gate across the track there were four cars parked on the opposite side with a number of people beside them.  When I arrived I said my hello’s and within a few minutes was sitting in a car with Jen, Rog and Archie Lewins being driven the remaining distance on the forest track back to my car.  This was a kind gesture given to a tired hill walker, thank you. 

 

Survey Result:

 

Rhinog Fawr

Summit Height:  720.9m (LIDAR)

Summit Grid Reference:  SH 65696 29009 (LIDAR) 

Bwlch Height:  352.6m (Trimble GeoXH 6000)

Bwlch Grid Reference:  SH 66446 28164 (Trimble GeoXH 6000)

Drop:  368.2m (LIDAR summit and Trimble GeoXH 6000 bwlch)

Dominance:  51.08% (LIDAR summit and Trimble GeoXH 6000 bwlch )

 

 

Rhinog Fach

Summit Height:  711.6m (converted to OSGM15)

Summit Grid Reference:  SH 66485 27017   

Bwlch Height:  560.6m (converted to OSGM15)

Bwlch Grid Reference:  SH 66561 26533

Drop:  151.0m (Submarilyn reclassified to Marilyn)

Dominance:  21.22%

 

 

Pt. 558.3m

Summit Height:  558.3m (converted to OSGM15)

Summit Grid Reference:  SH 66160 26783   

Bwlch Height:  535.3m (converted to OSGM15)

Bwlch Grid Reference:  SH 66225 26636

Drop:  23.1m

Dominance:  4.13%

 

 

For further details please consult the Trimble Survey Spreadsheet