Mapping Mountains – Trimble Surveys – UKHillwalking Article

UKHillwalking recently published an article on the Trimble survey of the highest mountain in Y Berwyn; Craig Berwyn.  The article and a link to it on the UKHillwalking website appear below.

Thanks to Alan Dawson for photos and details on Bernard Wright, Peter Collins for details relating to Bernard Wright and Aled Williams for suggesting and having input in to the article.

In Search of the 'Lost' Welsh Mountain

Through painstakingly re-measuring some of Britain's borderline summits, independent surveyors G&J Surveys have been responsible for elevating mere hills to mountain status, and dethroning Munros. G&J's Myrddyn Phillips describes his recent work on the highest point of the Berwyns, a mystery mountain that's never before been given an accurate height, and one particularly close to his heart.

Over 25 years ago a party of 20 were walking on the Berwyn mountains in Mid Wales. The party was being led by Bernard Wright, a former motor oils scientist from Tarvin in Cheshire. As they headed up to the main Berwyn ridge they were confronted by a peak that was absent from their Ordnance Survey maps.

The pointed summit of Craig Berwyn (left) and nearby Cadair Berwyn

Bernard and his friends were standing beside the trig pillar on Cadair Berwyn looking south toward Moel Sych. Both hills nowadays are given the same metric height of 827m. In Bernard's day the map had Moel Sych at 2713ft, and Cadair Berwyn at 2712ft. But something was wrong. The map indicated that these two summits were the highest in the Berwyn, but between the two was another hill, a hill that looked higher, but was not shown as such on any map. 

"Between what the map said were the highest two summits in the Berwyn was another, higher hill"

The group visited the unknown and seemingly 'non-existent' hill and Bernard sat on its highest rock and peered out over the top of Cadair Berwyn and Moel Sych. This hill was definitely higher, but why wasn’t it shown as such on the map? As the friends descended, they chatted about the hill and someone proposed that they should name it Berwyn Wright. A Welsh friend in the party suggested the name Craig Uchaf (...highest), and although an appropriate name it has never caught on.

More recent research I conducted for the ‘Y Pedwarau’ hill list (see UKH article here) revealed that the peak is known to some of the local farmers and shepherds as Craig Berwyn, a name that already appears on the Ordnance Survey map.

Trimble GeoXH 6000 on the key spot

Newspaper clipping from 1988

Back in the Eighties, Bernard reported his find to the Ordnance Survey and was told that the two 827m peaks were the highest points for miles around. Dissatisfied with this answer he persevered and gave detailed co-ordinates for the peak. This prompted the OS to examine their large-scale mapping, on which was found a tiny 830m ring contour that did not appear on the publicly available 1:50,000 and 1:25,000 maps.

The news of Bernard’s ‘new mountain’ hit the headlines, and soon the tiny 830m ring contour appeared on the new OS 1:25,000 Explorer map. However, one thing the Ordnance Survey never did was to give the mountain an accurate absolute height, relegating it to among the few principal Welsh mountains that do not have definitive values for elevation. As the summit is made up of a number of embedded rocks, all jutting out of the ground, the height could well be higher than thought. If an accurate height was given to the mountain, it would also be the culmination of a story that first started over 25 years ago when Bernard Wright and his friends came across a mountain that seemed not to exist.

"The Ordnance Survey never gave the mountain an accurate absolute height"

Here's where I entered the story, armed with a new piece of equipment; the Trimble GeoXH 6000. This fancy bit of kit only weighs 2lb and can achieve accurate height results in no more than five minutes. 

The Trimble GeoXH 6000 is proving to be a great piece of equipment to ‘screen’ hills with, as its precision is +/- 0.15m when compared to our Leica GS15 whose accuracy is +/- 0.05m, but only when we collect upwards of two hours of data. Any hill measured quickly with the Trimble whose height is close to a recognised threshold, such as 2000ft or 3000ft, can then be more slowly surveyed to a higher degree of accuracy with our Leica equipment.

The Trimble GeoXH 6000 gathers its ten minutes of data on the high point of Y Berwyn

However, this particular hill was more than a lump of rock that I wanted to place a bit of surveying equipment on top of. It held an emotional tie for me too, as I had scattered some of my father’s ashes from its highest point. The height of the hill had intrigued me ever since I'd read about Bernard Wright’s new mountain in the late 1980s.

The trip to survey Craig Berwyn proved quite an expedition as I wanted to survey all eleven hills and their respective cols that make up the Maen Gwynedd Horseshoe. This is an extended walk I've done on many occasions but never with the intent to carry out so many surveys. Of course it was the high point of Craig Berwyn that really interested me.

I set out on the 21^st June 2014. The surveying expedition would require many hours to complete, but I had settled weather, and the notorious peat paths of the higher Berwyn were dry. As the highest rocks of the Berwyn were approached a slight breeze picked up, but not enough to worry me as I placed the Trimble on the very highest point of the mountain range, the same spot that Bernard Wright had peered from all those years ago. The view from the summit took in all the higher Snowdonia peaks to the west as well as the lower hills towards the English border. In all the surveying trip took over 12½ hours to complete. 

Ten minutes of summit data were collected by the Trimble GeoXH 6000 and later post processed, giving a result of 831.98m +/- 0.15m.  So over 25 years since Bernard Wright first discovered the mountain its true height is now known, and at 832m it seems that the little 830m ring contour on OS maps is hiding quite a substantial rock under it!

Further details of this survey and others can be found on Myrddyn’s blog:

http://mappingmountains.blogspot.co.uk/2014/06/mapping-mountains-trimble-surveys-y_22.html

Please click {here} to see the original article published on the UKHillwalking website

Mapping Mountains – Trimble Surveys – Mynydd Hiraethog

22.08.14  Bryn Trillyn (SH 947 590)

Bryn Trillyn (SH 947 590)

Bryn Trillyn is positioned on the western fringe of Mynydd Hiraethog and looks out on desolation of moor.  It is easily accessible from the A543 which is just to its south-east.  The hill forms part of an extensive upland between the Welsh coast to the north, the Afon Conwy to the west, the hills of the Arennig to the south and the Afon Clwyd to the east.

This was my fourth and last walk of the day, and the second with Mark.  We’d just had a magical illuminated hour in the company of Moel Tywysog (SH 984 657) and confirmed its Pedwar status with a Trimble survey, we now wanted to watch the sun disappear behind the higher Eryri peaks and collect data to see if this 496m map heighted hill could become a fully-fledged Dewey.

We parked in a lay-by a few hundred metres south of the Sportsman’s Arms (SH 952 590).  This house is now for sale, it was once reputed to be the highest Inn in Wales, but the beer stopped being served a number of years ago.

We walked back up the road toward the Sportsman’s Arms and headed west over a foot stile on to a track, this leads to the summit of Bryn Trillyn, we diverged from the track and followed a fence line toward the heather moor.  Bearing left at the next fence junction directed us straight for the summit with reclaimed sheep pasture on the southern side of the fence and heather on the northern.  Mark chose the latter and I the former to walk on.  The heather was ablaze with delicate purples, all colour slightly diffused as the sun sank behind a thickening grey sky to the west.

Heading for the summit of Bryn Trillyn

We were now walking on a heather embankment which led straight to the high point of the hill, at one time this may have been a walled construction, but now nature has re-claimed it.  After we reached the summit Mark went off to investigate the ruin of Gwylfa Hiraethog, whilst I set the Trimble up on its improvised tripod on the high point of the hill.  This was on the heather embankment, and was something Mark and I discussed, as it may have once been a wall, but we both thought it could now be considered part of the hill, if indeed it had ever been some form of a wall.

Mark approaching the high point of Bryn Trillyn

As the Trimble attained its 0.1m accuracy and data were collected I looked up and Mark was standing in the centre of the ruin, much higher than my position as the rubble of the old house had been in situ long enough for it to be stabilised and for grass to grow on it, however we both agreed that this was definitely man-made.

The ruined Gwylfa Hiraethog

The subtle grey of the northern Carneddau

Gathering data at the first of three positions

Gwylfa Hiraethog was once a shooting lodge of Hudson Ewbanke Kearley; the first Viscount Devonport, whose main estate was Wittington House in Buckinghamshire.  Its origins date to the early 1890’s when a wooden chalet was erected; this was transported from Norway in prefabricated sections.  The chalet was later incorporated in to a larger stone built lodge, this was later enlarged in 1913 under the guidance of the architect Sir Edwin Cooper, photographs show the lodge as an imposing mansion in the Jacobean style, with a three gabled front with cross wings, long windows and a stone flagged floor.

Gwylfa Hiraethog was once an impressive house which was used as a shooting lodge

The Gwylfa Hiraethog estate was put up for sale by Viscount Devonport in 1925, it was then described as a shooting box with residence comprising 11 principal bedrooms, two secondary bedrooms and servant’s quarters.  Following the sale the lodge became the residence of the estate gamekeepers and was finally abandoned in the 1960’s.  Its subsequent deterioration has been rapid and it now stands as a ruin.

By now the thickening mass of grey cloud to the west was shielding the sun with only a flicker of piercing orange tailing out to the north, as the black outline of hills mirrored the deep blue of the sky.  This only lasted a few minutes as the blaze of sun disappeared from view, supplanted by twilight’s darkening.

The sun piercing the cloud and tailing out to the north

I definitely wanted to discover a new Dewey and insisted that the rubble strewn inner part of the abandoned old shooting lodge could definitely constitute the summit of a hill!  Therefore five minutes of data were collected from inside the house atop the grassed rubble.

Gathering data at the second of three positions

During this Mark investigated the moor and found a point that looked to be the highest outside of the heather embankment, once the Trimble had gathered its five minutes of allotted data from the top of the rubble summit I headed toward Mark.

Mark stands at the point for the third survey with his walking pole at the high point of the embankment on right of photo

In darkening conditions the Trimble was placed on its improvised tripod at the point Mark had found.  By now photography without the aid of using a flash resulted in a blurred image, once data were stored we headed down the grassed track back to the Sportsman’s Arms and the awaiting car.  Three points surveyed and my vote definitely goes toward the rubble summit!

Tryfan in centre background

Gathering data at the last of three positions

Survey Result:

Bryn Trillyn

Summit Height:  496.4m (converted to OSGM15)  

Summit Grid Reference:  SH 94748 59094

Bwlch Height:  446.5m (converted to OSGM15, from subsequent Trimble GeoXH 6000 survey)

Bwlch Grid Reference:  SH 96287 59668 (from subsequent Trimble GeoXH 6000 survey)

Drop:  49.9m

Dominance:  10.05%

 

 

For details on the bwlch survey of Bryn Trillyn

For further details please consult the Trimble survey spreadsheet click {here}

Mapping Mountains – Trimble Surveys – Mynydd Hiraethog

22.08.14  Moel Tywysog (SH 984 657)

Most evening’s just before sun set the hills can give up part of their beauty, when subtle accentuated deep colours wash over the landscape.  This period of time that the hill’s offer is all too brief and should be savoured as the illuminated colour with radiant greens and deep blacks of shadow is all too soon cast out. 

This evening atop Moel Tywysog in the hills of Mynydd Hiraethog the sun gave up part of this beauty as adjacent fields ran awash with colour and far off hills became grey silhouettes framed against a gentle sky, and all beside a hillside more reminiscent of a hay field with long beige grass swept aside leading up to a solidary trig atop mudstone.

The main reason for choosing Moel Tywysog as an evening wander was that the hill is conveniently placed next to a relatively high road and so access is made easy.  It is also conveniently placed in relation to Wrexham, where Mark had finished his daily chore of work and just eastward is Denbigh, where I met him for a fish supper in Morrisons café.  Another reason for visiting the hill is that it is given a map height of 400m with the flush bracket atop the trig being given a height of 400.668m in the OS Trig Database.  Therefore its Pedwar status had been questioned and Mark had done a reccie earlier in the year and examined the base of the trig which is built on local mudstone.  His verdict was that the base was definitely man-made.  Then, his visit was to a place with hillsides of close cropped green; whereas today the grass had grown and lost its luxuriant greenness, replaced with a yellowish tinge almost shining in the evening’s light.

Mark reccied the summit and found the trig built on a mud-stone base.  Photo: Mark Trengove

We set off for the summit of Moel Tywysog from a small gravelled area to the east where a tee junction of country lanes meet, the time was 6.45pm.  A gate gave us access to a vehicle track which headed uphill toward another gate and the higher part of the hill. 

Mark on the vehicle track that gave access to the higher part of the hill

As I walked up I looked around and took many photographs, some of Mark as he headed for the trig and others of the landscape which was now taking on that magical coloured radiance, to the east was the extended Clwyd ridge with Moel Fama and Foel Fenlli dominating the view.  To the west was Mynydd Tryfan with its three rocky tops being highlighted against the higher Eryri peaks that were cast in grey silhouette, all lined up with memories aplenty.

Heading for the trig

Mynydd Tryfan with the high peaks of Eryri as backdrop

To the north stood Moel Fodiar, a hill I have not yet visited, its upper hillsides of bracken and moor standing out against its lower reclaimed grazed fields of green, with the emeralds highlighted with evening colour.  Further to the west was what we had planned as our last hill for the evening; Bryn Trillyn, a 496m map heighted hill, now dark and foreboding showing an extended moorland top matched against lower pastoral fields of green.

Moel Fodiar with heather, fern and a patch of gorse contrasting the greens of lower fields

We examined the ground at the base of the trig from many angles and decided that the high point looked as if it was about one metre away from the mud-stone plinth, just on the eastern side of the trig.  As the Trimble quickly attained its 0.1m accuracy before data can be logged, Mark sat and watched the ever soothing view.

Mark enjoying the view

Once the ‘Log’ key was pressed I pottered around with camera in hand, taking photos of the trig as the richness of blue with western streaks of cloud met the tawny browns and yellows of swept grass, it was very fulfilling and all too soon over, as the illuminated colour for one evening had given itself and now the sun crept behind the western cloud and the colour dimmed, we also needed to press on toward Bryn Trillyn where we hoped to watch the sunset over the giants of Eryri.

Illuminated colour on the summit of Moel Tywysog

I took one or two quick photos of the Trimble position in relation to the trig and I then packed it away.  Before we headed down to the car we positioned an 18 inch wooden ruler flush with the top of the flush bracket, put a spirit level on the ruler and measured the height between the top of the flush bracket and the ground at the base of the mud-stone plinth with a steel tape.  This measurement came to 66.5cm, this ground is probably slightly lower when compared to the Trimble position, only a level and staff could determine by how much, this we didn’t have, but I’d guess the difference in height would be around 10cm.

The Trimble set-up position in relation to the trig

As we headed down the sky opened with streams of light cast out of a clouding sky.  The walk had only taken 45 minutes and much of that was setting up and then waiting for the Trimble to gather its data, as well as measuring the height from flush bracket to base of the trig plinthed mud-stone. 

Streams of light cast out of a clouding sky

The show of colour only ever lasts for 30 - 45 minutes or so, longer periods are rare, but if fortunate enough to experience the richness on offer, it is one aspect of the hills that can give up part of their beauty, it is to be savoured and appreciated.

   

Survey Result:

Moel Tywysog

Summit Height:  400.2m (converted to OSGM15) 

Summit Grid Reference:  SH 98480 65714

Drop:  42m

Dominance:  10.50%

  

For further details please consult the Trimble survey spreadsheet click {here}

Mapping Mountains – Hill Reclassifications – 100m Twmpau

Castell Dinbych (SJ 051 657) - 100m Sub-Twmpau reclassified to 100m Twmpau 

There has been a reclassification to the Twmpau list with a 100m Sub-Twmpau being reclassified to a 100 Twmpau due to a survey with the Trimble GeoXH 6000.  The hill is situated in the centre of Dinbych (Denbigh) in north-east Wales, and its name is Castell Dinbych (Denbigh Castle in English).  

The present construct is the remains of one of Edward 1’s fortifications after he visited his neighbours and asked them not to be so rebellious.  It is situated in an impressive position overlooking the town to the west and the Vale of Clwyd to the east.  In its time the castle must have been an imposing construction, one no doubt meant to subjugate.  

The critical bwlch of the hill may be placed in someone’s living room beside a road named Bryn Stanley; I asked permission to place the Trimble on a fence post adjacent to a front garden as satellite reception may have been awkward inside the bungalow.

The full details for the hill are:

Cardinal Hill:  Mwdwl Eithin

Summit Height:  143.2m (converted to OSGM15)

Name:  Castell Dinbych

OS 1:50,000 map:  116

Summit Grid Reference:  SJ 051 657

Drop:  33.0m (converted to OSGM15)

Castell Dinbych (SJ 051 657) is now reclassified to a 100m Twmpau

For details on the survey that confirmed this hill's 100m Twmpau status please click {here}

Myrddyn Phillips (August 2014)

Hill Lists – Cymru / Wales – 200m Twmpau updates – Mynydd Epynt

The first list to the Welsh 200m P30 hills was published on Geoff Crowder’s website v-g.me in 2000; this list preceded the list of TuMPs by nine years, the list proved a very useful resource for the TuMP compilation for this category of hill.

The Welsh 200m P30 list documents all hills in Wales that are at or above 200m in height and are below 300m in height, to qualify for the main list each hill requires a minimum of 30m of prominence.

The hills listed below are updates to the Welsh 200m P30 list originally published on Geoff Crowder's website.  To see the original list click {here}

The original published list had a Sub-List which was entitled ‘Hills to Survey’.  This list consisted of all hills in Wales in the stipulated height band that have a minimum of 20m of prominence, but do not meet the minimum 30m of prominence to enter the main list, according to Ordnance Survey map spot heights and contours.  Nowadays the standard Sub-List takes in all hills that have a minimum of 20m of prominence.  However, the Hills to Survey Sub-List discounted hills whose map spot heights gave a drop value of less than 30m, but more than 20m.  By doing so, the only hills that were Sub-Listed were those that map values dictated stood a chance of entering the main list, for example; if a hill had a summit spot height of 250m and a bwlch spot height of 221m, it was not listed in the Hills to Survey Sub-List as with 29m of drop I thought it did not stand a chance of main list qualification.

 

When compiling the Sub-List I was measuring many hills for P30 status using a basic levelling technique, please click {here} for more information concerning this.  I now know that Ordnance Survey spot heights have a standard margin of uncertainty of + / - 3m associated with their accuracy.  Therefore many hills that were not listed in the original Sub-List may have sufficient drop to enter the main list.  Because of this the Sub-List has been altered to include all hills that have a minimum of 20m of drop but are not known to attain the minimum 30m of drop to enter the main list.

The hills listed below are those major amendments to the original Welsh 200m P30 list as it appears on Geoff’s website.  There are many hills that have been promoted from the Hills to Survey Sub-List to the main list, whilst there are many additions to the Sub-List now that it has been standardised to include all 20m minimum but below 30m drop hills.

When the 200m P30 list was first published it was the first to this category of hills and in some way it and its other 100m height band lists paved the way for Clem’s data that later appeared on the RHB file database and then for the TuMPs listing by Mark Jackson.

As well as the first P30 list to this height band the list is now the first to include a comprehensive Sub-List.

TuMP baggers beware; as the main list also includes P30’s not listed by Mark Jackson, so if you want to visit all P30’s you’ll have to include some non TuMPs to do so.

The list will be updated on a weekly basis and will be done so through each Group category, starting from the north and working south.  The twentieth Group is Mynydd Epynt.

Mynydd Epynt

 

North of the Afon Gwydderig at SN 770 342 to SN 871 299 and then north of the Afon Wysg (River Usk) to SO 127 211, continuing west of small stream to bwlch at SO 142 225 and the Afon Llynfi to Llyn Syfaddan (Llangors Lake) and the Afon Llynfi to SO 178 389, continuing south of the Afon Gwy (River Wye) to SO 034 515 and the Afon Irfon to SN 893 459 and the Afon Cledan to bwlch at SN 840 432, continuing east from bwlch and the Afon Gwyddon and Afon Bran to SN 770 342.  Bordering with Y Mynydd Du, Fforest Fawr and Bannau Brycheiniog to the south, Mynyddoedd Duon to the east, Fforest Glud and the Elenydd to the north and the Elenydd to the west. 

    

Twmpau - 200m updates

Pt. 243m    243m    SO 126 320

This hill was originally listed with a part invented name of Moel Meiadd, as this is wholly  unnecessary the name of the hill has reverted to the Pt notation until further enquiry can take place.  The hill qualifies for the Welsh 200m P30 list as it has a 243m summit spot height on Ordnance Surveys maps and a bwlch spot height of 213m on the Ordnance Survey enlarged Geograph map.  These values give this hill 30m of drop.

Sub-Twmpau - 200m updates

Pt. 289m    289m    SN 927 456

Another hill name that follows the Pt notation as no appropriate name is known for it by the blog author.  As the hill has a 263m spot height at the bwlch on the Ordnance Survey enlarged Geograph map at SN 929 454, it gives this hill 26m of drop.

Pt. 256m    256m    SO 097 344

With a summit spot height of 256m and a bwlch spot height of 235m this hill has 21m of drop and therefore qualifies for the Welsh 200m Sub-P30 list.  The height of the bwlch is given as a 235m spot height on the Ordnance Survey 1:50,000 map at SO 097 346 and as a 235m spot height on the Ordnance Survey enlarged Geograph map at SO 098 347.

Coetgae Fawr    213m    SO 046 495

This hill’s bwlch contouring is between c 190m – c 200m and as its valley to valley contours are placed quite near to one another, the height of the bwlch has been estimated as c 192m, giving this hill c 21m of drop.

Pt. 282m    282m    SO 094 412

With a summit spot height of 282m and bwlch contouring between c 260m – c 270m with an estimated bwlch height of c 262m, this hill has c 20m of drop.

Pt. 276m    276m    SN 987 491

As no appropriate name is known for this hill by the blog author it follows the Pt notation.  The bwlch contouring is between c 250m – c 260m with the bwlch centred on SN 989 491 and estimated to be c 256m high, giving this hill c 20m of drop.

Next update due on the 1^st September 2014

Mapping Mountains – Trimble Surveys – Mynydd Hiraethog

22.08.14  Castell Dinbych (SJ 051 657)

Castell Dinbych (SJ 051 657)

Standing aloof above the small town of Dinbych (Denbigh) is a past stronghold of Edward 1’s campaign to pacify Wales.  This construction is Castell Dinbych (Denbigh Castle) which is now a ruin managed by Cadw; the Welsh heritage agency.  The site on which the remains of the castle are situated is impressive and also imposing as it looks down on the fertile plain of the Vale of Clwyd.

The first recorded stronghold on this site was Welsh and originally belonged to Llywelyn the Great, it was later held by Dafydd ap Gruffydd the brother of Llywelyn ap Gruffudd; the last Welsh Prince.  Once Edward had visited his rebellious neighbours the Welsh construct was torn down and supplanted with a new English fortress, the remains of which are on display looking out over Dyffryn Clwyd and Dinbych.

I’d wanted to visit this castle ever since first listing it in the Sub-List that made up the Welsh 100m P30 list that is published on Geoff Crowder’s website (to see the original list click {here}).  Soon after publication I added drop values to each of the 100m height band lists that appear on Geoff’s website, and based on bwlch contouring between c 100m – c 110m I’d estimated the height of the bwlch as c 113m, and as the hill that the castle sits on has a summit spot height of 143m, these values gave the hill c 30m of drop.  Since adding the drop values the Ordnance Survey have made public a rather helpful map that is published on the Geograph website, this map gives bwlch contouring between c 110m – c 115m, with the valley to valley contours being relatively close together, giving an estimated bwlch height of c 111m, giving a drop of c 32m.  It would also be a bit of fun trying to survey the top of a castle as well as trying to find the critical bwlch as it seemed to be placed in someone’s house on a road named Bryn Stanley.

I parked at the top of Love Lane, adjacent to the entrance to Castle Lane, and walked up the latter to the castle entrance, passing the castle walls and part of the foundation rock that it sits upon.  The entrance is through the remains of the three towered main gateway which is an imposing edifice to greet the visitor, Edward certainly knew how to impress through sublegation as his Welsh fortifications testify.

Once inside there is a modern construct with a ticket counter, entrance is £3.50 for adults.  People were sitting enjoying a coffee and looking out over the castle grounds, there are informative leaflets and books for sale, and a helpful artist’s impression on the wall of what the Castle once looked like.  I approached John Sherlock who is the Lead Custodian at the Castle and explained the purpose for my visit, John was soon offay with all details concerning Trimbles, hill lists and the finer detail of drop.  He kindly showed me the entrance door to the castle grounds and let me in for free, I thanked him and asked if the castle is closed outside of opening times, it seems it is not, therefore it seems entrance is free after 5.00pm as he informed me the castle never closes.

Artist's impression of how Castell Dinbych looked

Once in the grounds I headed toward the high point, which is relatively obvious to find and placed the Trimble on the neatly cropped grass near to high stone walls that make up part of the castle’s northern perimeter. 

As data were logged the sun shone and a few people roamed the lower parts of the castle, thankfully no one came near to the high point until ten minutes of data were collected, and even then the family who were walking their young child around the ruins did not approach the high point until the Trimble was closed off.

Gathering data at the high point of Castell Dinbych

Although bagging hills and doing surveys takes you to places that otherwise one wouldn’t visit, I felt that my brief sojourn to Castell Dinbych did not take in a full cultural experience, but as I had a 5.30pm rendezvous with Mark in Morrisons café I could not linger, and I still had to visit the bwlch.

Before leaving I visited John Sherlock and thanked him and walked back to the car and drove to Morrisons, and then walked back up the road toward Bryn Stanley and the area of this hill’s bwlch.  This I found at the end of the road that forms Bryn Stanley, next to a gravel turning area that gives access to a footpath heading in to a field to the south.

I considered setting the Trimble up on the gravelled area but the thought of having it run over for a second time did not seem prudent, so I had a good look at the area and decided that the critical bwlch was probably in or near to someone’s bungalow.  I picked which living room I thought the critical bwlch was situated in and knocked on the accompanying front door, I soon had permission to set the Trimble up on their garden fence adjacent to the road.

The southern view with the Trimble gathering data on the corner of the fence

The northern view with the Trimble gathering data at the critical bwlch of Castell Dinbych

I placed the Trimble on the draughts board which was used to create a flat surface on top of two adjacent fence post tops and measured the offset down to the road.  This still wasn’t ideal as cars could easily knock the Trimble off its perch if they turned in to the gravelled area and touched the slightly overhanging draughts board.  I kept a close eye on it and only asked one car to move on as it had stopped almost in front of it, with engine running for the occupant to make a mobile phone call.  Once ten minutes of data had been gathered I packed it away and walked back to Morrisons car park and awaited the arrival of Mr Trengove.

   

Survey Result:

Castell Dinbych

Summit Height:  143.2m (converted to OSGM15)  

Summit Grid Reference:  SJ 05168 65796

Bwlch Height:  110.2m (converted to OSGM15)

Bwlch Grid Reference:  SJ 04697 65704

Drop:  33.0m  (100m Sub-Twmpau reclassified to 100m Twmpau)

Dominance:  23.04%

For further details please consult the Trimble survey spreadsheet click {here}