Sunday, 24 September 2017

Mapping Mountains – Trimble Surveys – Arenig

01.07.17  Pen y Foel Ddu (SH 753 394), Foel Cynfal (SH 749 395), Pt. 548.6m (SH 743 393), Graig Wen (SH 739 394), Moel y Croesau (SH 748 383) and Pt. 369.5m (SH 739 374)

Pt. 548.6m (SH 743 393) with Arenig Fawr in the background

I’ve often looked over to my left when travelling the minor road beyond Llyn Celyn that skirts the wilds of the Y Migneint and heads toward Llan Ffestioniog, and often thought that an approach to the hills taking in Graig Wen looked a boggy and pathless affair, and therefore always shied away from making an ascent from this side, however this was the ascent route suggested by Aled and with a second car left at the entrance to Bryn-celynog it would give an opportunity to visit and Trimble a number of hills, including two marginal Uchaf hills, one of which had been on Aled’s radar for a number of months.

A green track confidently leaves the minor road and looks as if it’s heading straight up toward the hills, unfortunately it abruptly ends with a narrow path continuing next to the course of a fence line, this also soon peters out with only the remnants of sheep paths to follow.

Heading toward the first hill of the day

The fence line led us to ground beside the quietly situated Llyn Cors-y-barcud, which today was a tranquil spot nestled and forgotten amongst its reed grass and bog.  A grassed ridge of sorts headed up and I slowly followed Aled toward the first summit of the day.

Llyn Cors-y-barcud

Aled heading toward Pen y Foel Ddu

Pen y Foel Ddu is the last hill of any subsequent prominence on the eastern side of this compact group, I’d visited this hill in September 2005 when immersed in my basic levelling surveys (BLS) with the resulting drop value being 50ft 6˝ (15.4m).  There is an overgrown cairn at the summit and I quickly set the Trimble up on my rucksack which was positioned on its back as there was a brisk breeze blowing, measured the offset between its internal antenna and the ground below and joined Aled away from the equipment for its five minutes of allotted data collection.

Gathering data at the summit of Pen y Foel Ddu

The next three hills and their respective bylchau and summits came quickly and at each we assessed the lay of land and gathered another five minute data set.  After surveying the summit of Pen y Foel Ddu the next point to gather data from was its bwlch, this consists of a browned water laden bog, and data were gathered from the northern and southern extremities of its watery ground.  Whilst assessing these points a grouse shot up from immediately beside us, a busied flap of wings and off it went, I’ve experienced this on the hill many times over the years, but then three young grouse shot up in all directions, quickly followed by two others and finally a single youngster shot up and away, they flew off in all directions with some of the youngsters following each other and others just skimming the moor grass and coming to rest beyond our eyesight.  This all happened so quickly and straight at our feet, the mother later had the attentions of a hawk which flapped down for the kill, it again shot off heading this time toward Aled and rested in the grass close by using it and also probably us for cover.

Gathering data at one of two points surveyed for the critical bwlch position of Pen y Foel Ddu

Pen y Foel Ddu and its water laden bwlch from the ascent of Foel Cynfal

Heading west the next summit belonged to Foel Cynfal, a relatively flat topped hill without a spot height on any map that I’ve seen.  Once at its summit the ground was assessed and the point judged the highest chosen, and the Trimble set up to gather data.  As I waited beside Aled for the 300 datum points to be stored, the morning’s blue sky had changed slightly with bulbous clouds occasionally blocking the warmth and colour given by the sun, and with a forecast of rain sweeping in from the west at approximately 4.00pm – 5.oopm we knew we could not linger if we were to get back to the awaiting car, dry.

Gathering data at the summit of Foel Cynfal

The next bwlch was positioned to the west and the steep grassed slopes leading down to it helped in assessing its critical point, I headed to its northern extremity and as this looked like the boggied outflow we concentrated our assessment on its southern side, and again the Trimble was set up and gathered its allotted five minutes of data.

Gathering data at the critical bwlch of Foel Cynfal

Our next hill lay on the land heading toward Graig Wen and it was a hill that I’d surveyed with my old wooden staff in September 2005, resulting in its inclusion in the fledgling Uchaf list, I remembered that it has two tops and these were on display as we followed sheep paths and contoured up on ground toward it.  We judged the first top which is the more northerly as the higher.  I set the Trimble up on my rucksack which was laid on its back as the breeze whipped across the hill.  This summit is a fine one and it would be sad to see it go from the Uchaf list if proven to have less that 15m of drop, before heading down to its connecting bwlch we walked to the southern top and peered back and agreed that this was lower.

The land leading toward the two tops of Pt. 548.6m (SH 743 393)

Looking back toward Foel Cynfal

Gathering data at the summit of Pt.548.6m (SH 743 393)

The connecting bwlch proved more expansive than those previously encountered but assessing the lay of land from a number of directions and vantage points helped in judging the placement for the Trimble.  Once five minutes of data were stored the equipment was packed away and we headed up toward the cairned summit of Graig Wen.

Gathering data at the critical bwlch of Pt. 548.6m (SH 743 393)

Pt. 548.6m (SH 743 393)

Pt. 548.6m (SH 743 393) with Arenig Fach in the background on the right

I positioned the Trimble on the highest rock of the cairn having moved one or two to accommodate proper placement, then measured the offset to the highest ground at its base and sat with Aled waiting for five minutes of data to be collected.  By now a ribbon of grey cloud was emerging way off on the western horizon heralding the forecast rain, so once the Trimble was packed away I followed Aled back along the broad eastern ridge and down to a land of bog and wilderness.

Gathering data at the summit of Graig Wen

We aimed for a dry hummock close to where pylons crossed this land, this according to LIDAR data that Aled had analysed is where the critical bwlch of our next hill; Moel y Croesau, lay.  I felt knackered when we arrived but the ten figure grid reference obtained from Aled’s analyses soon led me to the correct Trimble placement and again the customary five minutes of data were gathered.

Gathering data at the critical bwlch of Moel y Croesau

The following ascent to the summit of Moel y Croesau seemed to go very quickly, and once there we used the LIDAR placement to zero in on one of two high points.  I soon assembled the Trimble on top of my rucksack which was again positioned on its back.  Our route down was via a gravelled track that heads through these hills that once must have given access to the small mines dotted beside the Afon Llafar. 

Emperor moth caterpillar

Gathering data at the summit of Moel y Croesau

Llyn y Garn with Moel Llyfnant in the background

The gravelled track led down to the remains of the old farm house of Dolddinas and the blue skies of earlier had now been replaced with white cloud as the westerly rain front edged ever nearer.  The track now turned in to a greened path that led up toward Llyn Hiraethlyn, as the high point of this greened path was only just below a Trichant we headed up to claim a new hill for both of us.  Once at the summit the Trimble was quickly set up to gather data, and away to the west the rain front was now depositing its wet stuff on a part of the Moelwynion, so we knew that we hadn’t beaten it and in all likelihood we were going to get wet.

One summit left to visit with Moel y Croesau in the background

The rain massing beyond Trawsfynydd

Gathering data at the summit of Pt. 369.5m (SH 739 374)

The Trimble set-up position at the summit of Pt. 369.5m (SH 739 374)

Following a fence line steeply down beside the remains of a grassed over stone wall led us down to the connecting bwlch.  Thankfully the bwlch was tight and therefore minimum assessment was necessary, as I packed the Trimble away after its data collection the first wind-blown raindrops fell and we quickened the pace on the continuation of the green track that we had left to head up and bag the Trichant.

Gathering data at the critical bwlch of Pt. 369.5m

The path led past the expansive Llyn Hiraethlyn, which must be another forgotten lake seldom visited and yet tranquilly placed.  Contouring the land beyond the path led down toward the old railway line that once went to Y Bala, by now the drizzled raindrops had disappeared east and a slight bright spell developed and remained with us as we headed under the old railway line and down across summer growthed fields with views of Y Garn and past the old farm house of Bryn-celynog to my car.

Llyn Hiraethlyn

Pt. 369.5m (SH 739 374)

Passing under the old railway that once went to Y Bala

A fine view of Y Garn

We’d visited six hills in all and surveyed each summit and five bylchau with only the bwlch for Graig Wen remaining un-Trimbled, with this compact group of hills making a fine circuit and one that portray a wild scene of landscape.  

Survey Result:

Pen y Foel Ddu

Summit Height:  531.2m (converted to OSGM15)

Summit Grid Reference:  SH 75395 39452

Bwlch Height:  514.6m (converted to OSGM15)

Bwlch Grid Reference:  SH 75250 39548

Drop:  16.6m (Uchaf status confirmed)

Dominance:  3.13%

Foel Cynfal

Summit Height:  545.5m (converted to OSGM15)  

Summit Grid Reference:  SH 74998 39546

Bwlch Height:  517.4m (converted to OSGM15)

Bwlch Grid Reference:  SH 74884 39528

Drop:  28.1m (500m Sub-Twmpau status confirmed)

Dominance:  5.16%

Pt. 548.6m

Summit Height:  548.6m (converted to OSGM15) 
Summit Grid Reference:  SH 74389 39398

Bwlch Height:  532.4m (converted to OSGM15)

Bwlch Grid Reference:  SH 74328 39295

Drop:  16.2m (Uchaf status confirmed)

Dominance:  2.95%

Graig Wen

Summit Height:  555.6m (converted to OSGM15) 
Summit Grid Reference:  SH 73910 39474

Drop:  139m

Dominance:  25.02%

Moel y Croesau

Summit Height:  490.6m (converted to OSGM15)  

Summit Grid Reference:  SH 74812 38345

Bwlch Height:  456.4m (converted to OSGM15)

Bwlch Grid Reference:  SH 75052 38555

Drop:  34.2m (Pedwar status confirmed)

Dominance:  6.97%

Pt. 369.5m

Summit Height:  369.5m (converted to OSGM15) 
Summit Grid Reference:  SH 73944 37497

Bwlch Height:  338.8m (converted to OSGM15)

Bwlch Grid Reference:  SH 74077 37523

Drop:  30.7m (Trichant status confirmed)

Dominance:  8.31%

Saturday, 23 September 2017

Mapping Mountains – Hill Reclassifications – Y Trichant

Penmaen Mawr (SH 698 755) Sub-Trichant addition

There has been an addition to the listing of Y Trichant initiated by a survey with the Trimble GeoXH 6000, with subsequent confirmation through analysis of LIDAR data by Aled Williams.  Y Trichant is the title for the hills in the 300m height band of the Twmpau (thirty welsh metre prominences and upward) and takes in all Welsh hills at or above 300m and below 400m in height that have a minimum 30m of drop, with the introduction to the re-naming of this list appearing on Mapping Mountains on the 13th May 2017.

The details relating to this hill’s addition as a Sub-Trichant are retrospective as its new classification was dependent upon a survey with the Trimble GeoXH 6000 which was conducted on the 14th July 2016.

The hill did not appear in the sub category that accompanied the original Welsh P30 lists when published on Geoff Crowder’s website, this sub category has now been standardised and named the Sub-Trichant and comprises all Welsh hills at or above 300m and below 400m in height with 20m or more and below 30m of drop.

The hill was not classified prior to the survey with the Trimble as much of the hill has been quarried and as is the norm in such circumstances there is a lack of uppermost contour lines on current Ordnance Survey maps.  But at one stage it was a part of a relatively substantial hill that had a prominence in excess of 100m and a 1,550ft (472m) summit map height shown on the Ordnance Survey Popular and New Popular One-Inch maps, with this height also appearing on the Ordnance Survey Six-Inch map published in 1888, and therefore it would have met the criteria specified for inclusion to the Humps and the main Y Pedwarau listings.  The subsequent quarrying has produced two distinct summits with the details given in this post relating to the higher of the two summits that are both known by the same name.  The hill no longer meets the qualification for these two listings as its summit has been quarried and current Ordnance Survey maps only give it an uppermost 370m contour line.  However, quarried areas are usually given no contour lines on Ordnance Survey maps indicating that the ground is or has been in flux, and photographic and map study by Aled indicated that the remaining high point was substantially higher than 370m.

The name of the hill is Penmaen Mawr and it is a part of the Carneddau range with its Cardinal Hill being Tal y Fan (SH 729 726) and is placed in the Region of North Wales (Region A, Sub-Region A1).  The hill is situated to the south of the A 55 road and is positioned between the towns of Llanfairfechan to its west and Penmaenmawr to its east, with the latter taking its name from the hill.

The hill can be easily accessed from a minor road to the south of the summit that reaches over 260m in height, a public footpath heads north from just below the high point of this minor road and joins a track designated a bridleway that contours around the southern slopes of the upper section of the hill.  A large section of the land above the bridleway is designated open access land and the summit of Penmaen Mawr is close to this.

The full details for the hill are:

Cardinal Hill:  Tal y Fan

Summit Height:  390.4m (converted to OSGM15)

Name:  Penmaen Mawr

OS 1:50,000 map:  115

Summit Grid Reference:  SH 69865 75523
Drop:  26.9m (converted to OSGM15)

Penmaen Mawr (SH 698 755) is now included in the listing of Sub-Trichant hills

Myrddyn Phillips (September 2017)

Friday, 22 September 2017

Mapping Mountains – Hill Reclassifications – Humps

Mynydd Caerau (SS 890 944) – Subhump addition

This is the thirteenth in a series of Hill Reclassification posts that detail hills whose status has been altered in the listing of the Humps (HUndred Metre Prominences) through map study and / or surveys that I have instigated.

This and forthcoming posts are retrospective as many of these hill reclassifications were initiated from studying the Ordnance Survey enlarged mapping that is hosted on the Geograph website, and for the reclassifications that affected the Humps the email sent to DJM&M was dated 03.10.12 and the details of this hill were then forwarded to Mark Jackson via email on the 04.010.12.

The listing of Humps was published in book format by Lulu in 2009 and entitled More Relative Hills of Britain, its author; Mark Jackson gives credit to a number of people who contributed toward the formation of this list, these include; Eric Yeaman, Alan Dawson, Clem Clements, Rob Woodall, Bernie Hughes, Pete Ridges and others.  When the list was published in book format there were 2987 Humps listed with their criteria being any British hill that has 100m or more of drop, accompanying the main list is a sub category entitled Subhumps, with the criteria being any British hill that has 90m or more and below 100m of drop.

More Relative Hills of Britain by Mark Jackson

The details for the reclassification appear below:

There has been a reclassification to the listing of the Humps (HUndred Metre Prominences) due to consulting the Ordnance Survey enlarged mapping that is hosted on the Geograph website, with these details being sent to Mark Jackson on 04.10.12.

Prior to this notification Mark Jackson had listed this hill with c 87m of drop based on the 555m spot height given to a triangulation pillar on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated bwlch height of c 468m based on bwlch contouring at 10m intervals.  However, with a 464m spot height appearing at the bwlch of this hill on the Ordnance Survey enlarged mapping hosted on the Geograph website it meant that when coupled with the 555m summit height it gave this hill 91m of drop, which is sufficient for it to be classified as a Subhump.  Since this notification LIDAR data has become publicly available and analysis of these data by Aled Williams gives this hill just under the 90m of drop required for Subhump status.

Extract from the Ordnance Survey enlarged mapping hosted on the Geograph website showing the 464m spot height at the bwlch of this hill

The hill is adjoined to the Y Cymoedd range of hills and is situated overlooking the A 4107 road to its north and the A 4064 road towards its south-east, with the small communities of Blaengarw and Pontycymer towards the hill’s south-east and Abergwynfi towards the hill’s north.

The addition of this hill to Subhump status was accepted by Mark Jackson and its new classification augmented in to the listing of the Humps on the 01.12.12.

The full details for the hill are:

Name:  Mynydd Caerau

Summit Height:  555m (as listed in the Humps)

OS 1:50,000 map:  170

OS 1:25,000 map:  166

Summit Grid Reference:  SN 89057 94411 (as listed in the Humps)

Drop:  91 (as listed in the Humps)

Myrddyn Phillips (September 2017)

Thursday, 21 September 2017

Mapping Mountains – Summit Relocations – The 500-Metre Tops of England and Wales

The 500-Metre Tops of England and Wales – Summit Relocations

The 500-Metre Tops of England and Wales are the English, Welsh and Manx hills at or above 500m and below 609.6m (2,000ft) in height that have a minimum drop of 30m.  The list is affectionately known as The Deweys.

The list is authored by Michael Dewey and the posts that have appeared on Mapping Mountains detailing the summit relocations to the list appear below presented chronologically in receding order.

Mapping Mountains - Summit Relocations - The 500-Metre Tops of England and Wales

Esgair Greolen (SN 835 920) - 1st summit relocation

First survey post for Esgair Greolen

Second survey post for Esgair Greolen

Michael Dewey has confirmed that the summit of Bryn yr Ŵyn (SN 83919 92571) is relocated to the higher summit of Esgair Greolen (SN 83574 92022) and therefore replaces Bryn yr Ŵyn as the hill listed in his 500-Metre Tops of England and Wales, which is affectionately known as the Deweys.

My word you’ve been busy in the Pumlumon area. Excellent work and I know it’s going to be appreciated by the people doing the Five-hundreds.  I’m pleased to accept the summit relocations of Bryn yr Ŵyn at grid reference SN 83919 9257 and Esgair Greolen at SN 83574 92022.

Michael Dewey (May 2016)

Esgair Greolen (SN 835 920) centre left of photo and Bryn yr Ŵyn (SN 839 925) on right of photo

The listing to The 500-Metre Tops of England and Wales appeared in Michael’s Mountain tables book which was published by Constable in 1995.  Since that date there have only been a few summit relocations which have resulted in replacement summits being confirmed, those affecting Wales include:

Pen y Bedw East Top (SH 784 470) replaces Pen y Bedw West Top (SH 779 469)

Cerrig Llwydion (SN 909 731) replaces Sychnentydd (SN 909 724)

Esgair Greolen (SN 835 920) replaces Bryn yr Ŵyn (SN 839 925)

Mountain tables by Michael Dewey

This summit relocation and replacement summit was confirmed by a survey conducted over two days; 05.05.16 and 13.05.16 with the Trimble GeoXH 6000.  In all five data sets were taken from the summit of Bryn yr Ŵyn and four from the summit of Esgair Greolen.  Each summit height has been averaged from these combined surveys:

Esgair Greolen 501.4m (converted to OSGM15) summit at SN 83574 92022

Bryn yr Ŵyn 499.9m (converted to OSGM15) summit at SN 83919 92571

Gathering data from the summit of Bryn yr Ŵyn

Gathering data from the summit of Esgair Greolen

If wanting more detail please consult the blog post for the 1st Trimble survey and the 2nd Trimble survey of these summits.  All details relating to each data set taken during the two days which took in these surveys are given in the Trimble Survey Spreadsheet.

Myrddyn Phillips (May 2016)