Mapping Mountains – Significant Name Changes – Y Pedwarau

Bwlch Bank (SO 242 720)

There has been a Significant Name Change to a hill that is listed in the Y Pedwarau, with the height of the summit confirmed by a survey with the Trimble GeoXH 6000 which took place on the 19^th April 2018, and the height of the bwlch ascertained from LIDAR analysis conducted by Aled Williams.

The criteria for the list that this name change applies to are:

Y Pedwarau – Welsh hills at and above 400m and below 500m in height that have 30m minimum drop.  The list is co-authored by Myrddyn Phillips and Aled Williams, with the introduction to the Mapping Mountains publication of the list appearing on the 30^th January 2017.

The hill is adjoined to the Beacon Hill range of hills, which are situated in the north-eastern part of Mid and West Wales (Region B, Sub-Region B1), and is positioned between the B4355 road to the north-east and the A488 road to the south-east, and has the small town of Tref-y-clawdd (Knighton) to the east.

Bwlch Bank (SO 242 720)

The hill appeared in the 400m P30 list on Geoff Crowder’s v-g.me website under the name of Bailey Hill.  Hill list authors are prone to list a hill by the name that appears nearest to its summit on contemporary Ordnance Survey maps, without much consideration for its local or historical confirmation, or whether map placement is appropriate, and in the case of this hill it was examination of Ordnance Survey historical maps and local enquiry that confirmed the name of the hill and the land area that constitutes that of Bailey Hill respectively.  

Bailey Hill

426m

SO242720

137/148

201

Clem/Yeaman

Since publication of these P30 lists on Geoff Crowder’s v-g.me website there have been a number of Ordnance Survey maps made available online, some of these are historical such as the series of Six-Inch maps on the National Library of Scotland website, whilst others are current and digitally updated such as the Interactive Coverage Map hosted on the Geograph website.  Two of the historical maps now available are the Ordnance Survey Draft Surveyors map which formed the basis for the Ordnance Survey One-Inch ‘Old Series’ map, and it was the former of these maps that name the hill as Bwlch Bank.

Extract from the Ordnance Survey Draft Surveyors map

The Draft Surveyors maps consist of the preliminary drawings made by the Ordnance Survey’s surveyors between the 1780s and 1840 and formed the basis for the first publicly available One-Inch map.  They were drawn at scales of six inches to the mile for areas considered of particular military significance and down to two inches to the mile for other areas.  Fair copies were then produced from these preliminary drawings to one inch to the mile and then copper plates were prepared for printing.  The Draft Surveyors maps for the whole of Wales are now available online and they form an important part in the study of Welsh upland place-names as they bridge the time frame between the late 18^th century and the mid-19^th century when the Ordnance Survey produced their first One-Inch maps.

The placement of names on maps from one scale to another and from one edition to another are prone to be moved over time, however study has shown that one of the best publicly available Ordnance Survey maps for name placement is the 1:25,000 historical map and this map also shows the name of Bwlch Bank adjoined to this hill.

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

When visiting this hill place-name enquiries were made with a number of local farmers and Bailey Hill was confirmed to take in a large area associated with a number of individual hills and is not applicable just to this hill, this is in evidence on the Ordnance Survey Draft Surveyors Map as well as the historical 1:25,000 map, both of which use the name of Bailey Hill as an elongated ridge name, whereas the contemporary 1:25,000 Explorer map dispenses with the use of an elongated ridge name giving the impression that this name is applicable just to one hill and not a large area of land taking in more than just this one hill.

Guy Hodnett from Brookhouse Farm

John and Liz Riberts from the Racecourse Farm

David Williams from White Anthony Farm

Therefore, the name this hill is now listed by in the Y Pedwarau is Bwlch Bank, and this was derived from the Ordnance Survey Draft Surveyors map and substantiated by the Ordnance Survey historical 1:25,000 map, with the land area taking in Bailey Hill confirmed by local enquiry.

The full details for the hill are:

Group:  Beacon Hill

Name:  Bwlch Bank

Previously Listed Name:  Bailey Hill

Summit Height:  424.9m (converted to OSGM15)

OS 1:50,000 map:  137, 148

Summit Grid Reference:  SO 24234 72023

Drop:  95.1m (Trimble summit and LIDAR bwlch)

The Trimble GeoXH 6000 gathering data at the summit of Bwlch Bank (SO 242 720)

For details on the survey of Bwlch Bank

Myrddyn Phillips and Aled Williams (June 2018)

Mapping Mountains – Significant Height Revisions – 100m Twmpau

Bryn y Beili (SJ 235 643)

There has been a Significant Height Revision initiated by a survey with the Trimble GeoXH 6000 to the listing of the 100m Twmpau (thirty welsh metre prominences and upward), with these details being retrospective as the survey that resulted in this height revision was conducted on 8^th April 2014.  With the criteria for 100m Twmpau status being all Welsh hills at or above 100m and below 200m in height that have a minimum 30m of drop.

The name of the hill is Bryn y Beili (Bailey Hill in English) and it is situated in the Bryniau Clwyd range of hills and is positioned in the town centre of Yr Wyddgrug (Mold), which is situated in north-east Wales.  The survey was conducted in the company of Mark Trengove over two days, three weeks apart, and it was Mark who proposed that this hill was a candidate for becoming a new P30, his inclination proved correct.  With the first survey concentrating on the bwlch and which resulted in an unfortunate incident when the Trimble wrestled with a car and was run over, whilst the second survey concentrated on the summit of the hill.

The hill can be accessed from the top of the High Street in Yr Wyddgrug (Mold), although the hill is prominent within the town it is almost hidden from view as it rises behind the former Pendref Chapel and is surrounded by a high wall, trees and shrubs.

The summit height of Bryn y Beili has been increased from its current Ordnance Survey map height, as prior to the survey with the Trimble GeoXH 6000 the hill was not listed as it only had an uppermost ring contour of 130m on Ordnance Survey 1:25,000 Explorer maps, with a 135m spot height appearing on lower ground in the centre of a bowling rink on the Ordnance Survey enlarged mapping hosted on the Geograph website.  The hill's new summit height is 143.0m (converted to OSGM15) which is 8.0m higher than the 135m spot height.

The full details for the hill are:

Cardinal Hill:  Moel y Gamelin

Summit Height (New Height):  143.0m (converted to OSGM15)

Name:  Bryn y Beili

OS 1:50,000 map:  117

Summit Grid Reference:  SJ 23544 64367

  

Drop:  31.5m (converted to OSGM15)

Bryn y Beili, a new P30 and a hill whose height has been significantly revised

For details on the survey that significantly revised the summit height of this hill

Myrddyn Phillips (August 2015)

Mapping Mountains - Hill Reclassifications – 100m Twmpau

Bryn y Beili (SJ 235 643) - 100m Twmpau addition

There has been a new addition to the Welsh 100m P30 list due to a recent survey with the Trimble GeoXH 6000.  The hill is situated in the centre of Yr Wyddgrug (Mold) in north-east Wales.  The name of the hill is Bryn y Beili (Bailey Hill in English), and it is almost hidden from view when approaching from the High Street as it rises behind the former Pendref Chapel and is surrounded by a high wall, trees and shrubs.  

Bryn y Beili has the remains of a Norman castle on its summit which may have been built on a much earlier burial mound.  This hill lends its name to the current usage of Yr Wyddgrug and Mold as the name of the town; yr, gŵydd, crug (high hill, the prominent mound) in Cymraeg, and mont, hault in Norman French.  

The hill was proposed by Mark Trengove as a potential new P30 and involved an exciting survey as the Trimble GeoXH 6000 was run over by a car whilst surveying in the area of the bwlch.  Our second survey attained a good data set from the tree covered summit and was backed up with a basic levelling survey from the position of a spot height just below the summit.

The full details for the hill are:

Cardinal Hill:  Moel y Gamelin

Summit Height:  143.0m (converted to OSGM15)

Name:  Bryn y Beili

OS 1:50,000 map:  117

Summit Grid Reference:  SJ 235 643

Drop:  31.5m (converted to OSGM15)

Bryn y Beili (SJ 235 643), the new 100m Twmpau

For details on the survey that promoted this hill to 100m Twmpau status please click {here}

Myrddyn Phillips (May 2014)

Mapping Mountains – Trimble Surveys – Moel y Gamelin

18.03.14 and 08.04.14  Bryn y Beili (SJ 235 643)

Bryn y Beili (SJ 235 643)

And what a dramatic day this turned out to be!  It had started with a visit to Moel Ffagnallt (SJ 189 700) a rather unimposing small hill above the hamlet of Rhes-y-cae.  I was with Mark Trengove who had suggested a day spent looking for ‘new’ P30’s, Moel Ffagnallt was the first possibility (it just failed with 27.2m of drop).  The second possibility was Bryn y Beili (Bailey Hill in English).

At the top of Bryn y Beili is an impressive motte and bailey built on an old glacial mound, just below the summit is a bowling green which has a 135m spot height on it on the Ordnance Surveyed enlarged Geograph map.  It also has a small recreational area with a slide, and a stone gorsedd circle where John, Graham and I filmed one of the introductory videos to the survey of Tryfan.  We used the upright stones to demonstrate how we planned to survey Adam or Eve.

The rise from the bowling green to the top of the motte is steep; we estimated it as a minimum of 5m, placing the height of the summit at approximately 140m (+/- 2m).  The critical bwlch for the hill lies in the cobweb of roads near to the centre of Mold with the northerly valley to valley contour making its way up (south) Ffordd Pennant until it reaches the junction with Gwernaffield Road.  Just east of this road junction is Park Avenue, which is the opposing road on the valley to valley traverse that makes its way up (north) until it reaches the junction with Gwernaffield Road.  This latter road junction has a 111m spot height on the Ordnance Survey enlarged Geograph map.

We parked on Ffordd Pennant and assessed the area of the bwlch as we walked into town for a relaxing hour in a pub with dinner time grub.  Whilst walking from the car down (or should that be up) Gwernaffield Road we realised that we would probably need two data sets from the road as it seems quite flat for 200 metres or so.  From one direction it seemed to be going up and when looking back at the previously sighted point from the point of upness it also seemed to be going up.  We debated this predicament and assessed the upness from a number of points.  During lunch we struck upon a cunning plan and decided that a shop in Mold must sell a surveying implement that may solve the ‘upness’ problem.  The surveying implement was found in a joke shop, it cost £2.50 (money well spent!), with the theory being that when the newly bought, expensive surveying implement was placed on the ground it would roll downhill.  Unfortunately it was a little windy and the technicalities of the surveying procedure quickly got out of hand as the surveying implement kept being blown uphill.  This resulted in a number of giggles and the thought of what John and Graham would think about the whole thing!  A photograph of the expensive surveying implement appears below.

Mark proudly holds the expensive surveying implement

Once we were fed we walked back to the area of the bwlch and visited the car to pick up all necessary gear, we deposited the football in the boot as its surveying life was probably not a lengthy one.  Our next stop was the junction of Gwernaffield Road and Park Avenue, this is where the 111m spot height appears on the OS enlarged Geograph map.  The Trimble was placed on the pavement near to the road and whilst it gathered its ten minutes of data Mark headed south to assess the bwlch from that direction, and I kept my eye fixed on all traffic as I didn’t want the Trimble to end up as road kill.  We then headed further down / up Gwernaffield road to the second point where we wanted to gather prospective bwlch data from.

At the junction of Gwernaffield Road and Park Avenue - gathering data next to roads can be highly dangerous for Trimbles

Again the Trimble was positioned on the pavement near to the road, we stood about four metres away, sufficiently close to grab it if any rogue car decided to try and squash it, but also sufficiently far away from it that we wouldn’t disrupt satellite coverage.  It took quite some time to get toward the required 0.1m accuracy before starting to ‘Log’ data; this was due to it having cars passing it every few seconds.  During this time Mark and I chatted and waited patiently.  I remember looking to my right and being shocked to see a car on the pavement, having cut the corner of the road junction, at that stage I remember being quite horrified as its front wheel had already passed the Trimble by inches, but its rear wheel was on a collision course with a very expensive bit of surveying equipment.

DON'T SQUASH THE TRIMBLE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I shouted in desperation for the driver to stop and then watched as he drove straight over the Trimble.  The car’s rear wheel went straight over the centre of the Trimble and kicked it up slightly from the pavement.  I expected to see it completely crushed and splintered across the pavement, remarkably it sat there in one piece.  Hard little beasts these Trimbles!  The driver realised that something was amiss because of me dashing towards his car shouting just before he tried to kill it.  He stopped and got out and was very apologetic, we spoke for two or three minutes, he apologised profusely, and as it was still in one piece and I was probably more concerned with its immediate welfare than anything else, I didn’t think about asking or swapping insurance details.  After a few minutes he got back in to his car and drove off.  I inspected the Trimble and the only external damage seemed to be on the outer casing on the back, where the force of the impact had scuffed the black surround.  Slight external damage is one thing but it is the prospect of internal damage that is the concern.

Battered

Bruised

But still intact

On our way to the top of Bryn y Beili we chatted about the incident.  Once on top we set the Trimble up, firstly on the floor operating with its internal antenna, and secondly on its 2m pole, operating with its external antenna.  On both occasions it didn’t reach its required 0.1m accuracy, therefore we did not ‘Log’ any data.  The nearest it reached was 0.12m with its external antenna.  The reason for this may be because of the mature tree coverage around the summit area.  But of course it may be because the Trimble was in a state of unrepairable shock.

Mark suggested we take a data set on a field close to his house, which we did.  The accuracy of 0.1m was reached; it gathered data and this was then post-processed with no seeming problem.  I then gathered a data set from a datum point outside my bungalow later that night and post-processed the data the following morning.  The standard deviation was o.6 which is very poor and the height was 0.5m below the usual measurement.  This latter data set coupled with the screen showing signs of flickering when trying to gather data at the top of Bryn y Beili is a sign for concern.

The Trimble will have to be looked at by the experts at KOREC UK.  This has been organised and I await their assessment.  I suspect there will be no more Trimbling for a few weeks.  Hopefully when looked at/ repaired/ replaced we can come back to Bryn y Beili and survey its summit.  But until then the GeoXH 6000 is in the Trimbe hospital being assessed.

I handed the Trimble over to Martyn Palmer at a service station off the M54 near to Telford.  He set it running next to a new 7series Trimble, operating each machine in sync with the other, his first assessment was encouraging as he said he would be amazed if there was any internal damage.  After a coffee and a good chat Martyn took the Trimble off to the workshop at KOREC UK in Huntington.

Can I have the nice pretty new one on the right please sir?

Martyn Palmer assessing the XH 6000 against the new 7series

Two weeks later it was delivered back to me with a clean bill of health, quite remarkable considering a car tried to squish it to smitherines.  Bryn y Beili awaited and it had to be surveyed with Mark.  We decided upon this evening, a lovely early spring day with blue sky, a slight breeze and daylight hours extending to just beyond 8.00pm.

I parked in Mold and by 5.00pm I was on top of the hill, having paid my respects to the scene of the crime.  Mark was due to meet me at 6.00pm.  I first tried the Trimble on the high point using its internal antenna whilst on the ground.  It achieved 0.12m accuracy, but never the 0.1m required to start logging data; pesky tree coverage was to blame.

The scene of the crime with Bryn y Beili in the background

I’d brought my old measuring staff as the bowling green on the south of the motte has a 135m spot height on it on the Ordnance Survey enlarged Geograph map, it also has good clear sky above it, so if the tree coverage hampered data gathering at the summit, we could at least gather data on the bowling green and then survey from this point to the summit using my old staff.

Although the Trimble didn’t achieve its required 0.1m accuracy it was great to be out with it again.  I then decided to try it at the gorsedd circle just to the north of the motte, if I could get data from here we could use the old staff to measure up to the high point.  Twenty minutes later and it still hadn’t reached the required accuracy; it slowly crept down toward 0.1m but kept bouncing back up when reaching 0.15m.  When this happens experience has taught me to be patient, as each time it creeps back toward the required accuracy it seems to get closer before bouncing back up again.  But after the third or fourth time of this happening I decided to visit the Bowling Green and its view of clear sky.

The view of the motte from the gorsedd stone circle

I paced out the bowling green and put the Trimble where I imagined the spot height appeared on the map.  It was 5.50pm by the time the Trimble attained 0.1m and I celebrated by quickly pressing ‘Log’.  A few minutes later and Mark appeared in his trendy surveying threads.  We gathered data at the bowling green for 20 minutes and then line surveyed from this point to the summit; the height difference came to 26½ft / 8.1m.  We’d already estimated that if this figure came to 7m or more Bryn y Beili would probably be a new P30.  But we really needed to get a good data set from the summit.

Gathering data on the bowling green with the motte behind the trees in the background

One last try and this time we set the Trimble up on its 2m pole, pushing this in to the ground for extra stability whilst also using its bipod.  The distance from bottom of antenna to the ground was measured and input as a measurement offset and we then waited and hoped that the magical 0.1m would appear on the screen.  Every few minutes I checked it and every few minutes the figure crept down; 0.19, 0.15, 0.13 and then 0.11m, the closest yet.  A few minutes later and there it was – 0.1m – at last!

Mark watches for rogue cars as the Trimble GeoXH 6000 eventually attains its 0.1m required accuracy

It only took a road accident, over three weeks and four goes on the summit to get the required accuracy.  Once ‘Log’ was pressed I joined Mark and we waited until over 30 minutes of data had been collected.  All that was left was to pack everything away and visit a pub for an evening meal, an excellent way to end a very fulfilling evening’s survey.

Survey Result:

Bryn y Beili

Summit Height:  143.0m (converted to OSGM15) (significant height revision) 

Summit Grid Reference:  SJ 23544 64367

Bwlch Height:  111.5m (converted to OSGM15)

Bwlch Grid Reference:  SJ 23251 64429

Drop:  31.5m (100m Twmpau addition)

Dominance:  22.02%

The survey on the bowling green came to 135.276m (converted to OSGM15), the height from this point to the summit using the old staff was measured as 8.077m.  Therefore the absolute height of the hill from this back-up survey is 143.4m.  Whilst doing the survey Mark asked me the margin of uncertainty associated with using the old measuring staff over the distance and terrain from the bowling green to the summit, I estimated +/- 1ft / 0.3m.

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