Thursday, 15 June 2017

Mapping Mountains – Hill Reclassifications – Y Pellennig –The Remotest Hills of Wales


Y Pellennig –The Remotest Hills of Wales – Hill Reclassifications

Y Pellennig –The Remotest Hills of Wales are all Welsh hills whose summit is 2.5km or more from the nearest paved public road and have a minimum drop of 15m, with the Change Register to this list available on Mapping Mountains.

The list is co-authored by Myrddyn Phillips and Aled Williams and the posts that have appeared on Mapping Mountains detailing the additions and deletions to this list appear below presented chronologically in receding order.







Mapping Mountains - Hill Reclassifications - Y Pellennig - The Remotest Hills of Wales

Pembrey Forest (SN 393 016) - Pellennig deletion (6th reclassification)


There has been a deletion of a hill from the list of Y Pellennig – The Remotest Hills of Wales, due to analysis of LIDAR data by Aled Williams.  The criteria for qualification as a Pellennig is any hill in Wales whose summit is at least 2.5km from the nearest paved public road and the hill having a minimum drop of 15m.  The list of Y Pellennig – The Remotest Hills of Wales is available as a downloadable e-booklet or print-booklet version on Mapping Mountains Publications with the up-to-date master list available on the Mapping Mountains site.

The hill is situated in the west south-western part of the Mynydd Sylen group of hills and as its name suggests; it is a part of a relatively large area of land comprising almost 2,500 acres of woodland whose south-western boundary borders sand dunes with the sea beyond.  Its Cardinal Hill is Mynydd Sylen (SN 515 080) and it is placed in the Region of South Wales (C-1).  The hill and conifer plantation is named the Pembrey Forest and it is situated with the community of Pen-bre and the town of Porth Tywyn (Burry Port) to its east south-east.   

The hill can be accessed from one of the main forest tracks that emerge out of the Pembrey Country Park to its south-east, or from a public footpath to its north that forms a part of the Wales Coastal Path.

The name of the hill is Pembrey Forest and it was listed as a Pellennig with 2.560km distance between its summit and the nearest paved public road and with c 18m of drop.  The previously listed summit is positioned at SN 390 021, this position is to one of five 25m ring contours that are shown on the Ordnance Survey 1:25,000 Explorer map, and importantly this ring contour is the furthest from any paved public road.

The deletion of Pembrey Forest from the listing of Pellennig hills is due to analysis of LIDAR data by Aled Williams.  LIDAR (Light Detection & Ranging) is highly accurate height data that is now freely available for much of England and Wales.

Aled’s analysis of LIDAR data to the highest natural ground within the forest gives the hill the following details:


Pembrey Forest

Summit Height:   27.1m

Summit Grid Reference:  SN 39390 01694

Bwlch Height:  9.5m

Bwlch Grid Reference:  SN 38702 02181

Drop:  17.6m

Remoteness:  2.360km from SN 41696 02197 (does not qualify on distance) 


The bwlch position given above connects this hill to the Pembrey Forest Ski Slope, which is given a much larger 25m ring contour and also a 30m ring contour; although in all probability the summit has been altered during the building of the ski slope.  The critical bwlch for whichever high point is taken is positioned at SN 409 019 and is c 7m high.

The summit previously listed in the Y Pellennig list is to the north of the details to the hill given above, and its LIDAR data came to:


24.8m at SN 38984 02162


However, there is a higher summit in the vicinity of the old Pellennig summit and this hill’s details was also analysed with LIDAR data, these are given below:


Pembrey Forest

Summit Height:   25.7m

Summit Grid Reference:  SN 39118 02003

Bwlch Height:  13.4m

Bwlch Grid Reference:  SN 39288 01922

Drop:  12.3m (does not qualify on drop)

Aled’s analysis of LIDAR data gave the hill a 27.1m summit height at SN 39390 01694, and a 9.5m bwlch height at SN 38702 02181 (bwlch position connecting to probable artificial summit of ski slope), these values give this hill 17.6m of drop, and a 2.360km distance from the nearest paved public road which is insufficient for it to retain its Pellennig status.

This now brings the overall total for Y Pellennig to 168 hills for the Complete list (All Wales), with the total for the Mainland Wales list being 124 hills.  The Master List will be duly updated on the Mapping Mountains site.


The full details for the hill are:

Cardinal Hill:  Mynydd Sylen

Summit Height:  27.1m (LIDAR data)

Name:  Pembrey Forest

OS 1:50,000 map:  159

Summit Grid Reference:  SN 39390 01694 
   
Drop:  17.6m (LIDAR data)

Distance:  2.360km


The list of additions and deletions in the Pellennig list since the 1st edition of Y Pellennig – The Remotest Hills of Wales was published by Europeaklist (1st edition, April 2015) is as follows:


ADDITIONS







DELETIONS


Pembrey Forest (SN 393 016)



Y Pellennig – The Remotest Hills of Wales is now published by Mapping Mountains Publications (2nd edition, July 2016).


Myrddyn Phillips and Aled Williams (January 2017)






Mapping Mountains - Hill Reclassifications - Y Pellennig - The Remotest Hills of Wales

Esgair y Llyn (SN 841 701) - Pellennig addition (5th reclassification)


There has been a new hill that has entered the list of Y Pellennig – The Remotest Hills of Wales, due to detail on the Ordnance Survey enlarged mapping on the Geograph website aided by analysis of LIDAR data by Aled Williams.  The hill is situated in the Elenydd group of hills which are positioned in the central part of the Region of Mid and West Wales.

This grouping of hills forms one of the wildest in Wales and takes in some of the most remote hills in the country.  The hill is situated in an immense grassland of moor and tussocks with Llyn Cerrigllwydion Isaf to its south-east and the higher summits of Cnapyn Drawsffos (SN 834 706) to its north-west and Blaen Rhestr (SN 843 693) towards its south.  Any towns or villages are a far distance away with Ysbyty Ystwyth towards the west and Rhaeadr Gwy (Rhayader) towards the east.

The hill can be accessed from its north-east via a track that leads to the farmhouse of Glanhirin, a path then leads toward and up the north-eastern ridge of Blaen Rhestr.  However, an alternate route is from the east north-east via the Monks Trod, which is an ancient route across the hills developed by the Cistercian monks as a bi-way between the abbeys of Cwm-Hir and Strata Florida.  Whichever way is chosen it leads into land that is open and featureless, and when visiting the hill a day comprising good weather is highly recommended.

The name of the hill is Esgair y Llyn and its inclusion as a Pellennig was spotted by Aled as the Ordnance Survey enlarged mapping on the Geograph website gives this hill a 529m summit spot height and a 513m bwlch spot height, these values give the hill 16m of drop which is sufficient to enter the list of Pellennig hills with the caveat of the distance from the hill’s summit to the nearest paved public road being a minimum of 2.5km.  As Aled was analysing other hills in the vicinity against LIDAR data, he did likewise with Esgair y Llyn.  LIDAR (Light Detection & Ranging) is highly accurate height data that is now freely available for much of England and Wales.

Aled’s analysis of LIDAR data gave the hill a 528.8m summit height at SN 84118 70177, and a 513.3m bwlch height at SN 83811 70087, these values give this hill 15.5m of drop which is sufficient when coupled with its summit being 4.535km from the nearest paved public road for qualification as a Pellennig hill.

This now brings the overall total for Y Pellennig to 169 hills for the Complete list (All Wales), with the total for the Mainland Wales list being 125 hills.  The Master List will be duly updated on the Mapping Mountains site.


The full details for the hill are:

Cardinal Hill:  Carny yr Hyrddod

Summit Height:  528.8m (LIDAR data)

Name:  Esgair y Llyn

OS 1:50,000 map:  135, 136, 147

Summit Grid Reference:  SN 84118 70177
     
Drop:  15.5m (LIDAR data)

Distance:  4.535km


The list of additions and deletions in the Pellennig list since the 1st edition of Y Pellennig – The Remotest Hills of Wales was published by Europeaklist (1st edition, April 2015) is as follows:


ADDITIONS




Esgair y Llyn (LIDAR data) (SN 841 701)



DELETIONS






Myrddyn Phillips and Aled Williams (December 2016)






Mapping Mountains - Hill Reclassifications - Y Pellennig - The Remotest Hills of Wales

Bryn Llwyd (SN 835 920) - Pellennig addition (4th reclassification)

1st Survey post and 2nd survey post for Bryn Llwyd

Significant Name Changes post for Bryn Llwyd  


There has been a new hill that has entered the list of Y Pellennig – The Remotest Hills of Wales, due to a recent Trimble survey.  The hill is situated in the Pumlumon group of hills in the northern part of mid Wales and is situated between the towns of Llanidloes to its south-east and Machynlleth to its north-west.

The hill was surveyed over two days on 5th and 13th May 2016, both in beautiful sunshine and its name is Bryn Llwyd.  It can be accessed from the east via a track that leaves a minor road toward the farm of Nant-yr-hafod, or alternatively it can be accessed from its north via a track that leaves a minor road leading toward the lake of Glaslyn, or from a track that leaves the same minor road and makes its way around the southern flank of Y Grug.  These approaches from the north have to contend with Cors yr Ebolion, which as its Welsh name suggests is a bog.  If tempted by one of these northern approaches it is advisable to keep to a path that contours the eastern flank of Banc Bugeilyn before losing height to cross the reed infested stream close to the south-west corner of the conifer plantation to the north of this hill’s summit.

Bryn Llwyd was surveyed by the Trimble GeoXH 6000 as being 501.4m (converted to OSGM15, and average of four summit surveys) high, and prior to this survey the highest point listed hereabouts was Bryn yr Ŵyn which had been regarded as being higher than Bryn Llwyd and therefore listed as the summit in the 500m Twmpau list.  However, Bryn yr Ŵyn was surveyed by the Trimble as being 499.9m (converted to OSGM15, and average of five summit surveys) high, and as contour interpolation and a rudimentary survey suggested that the connecting bwlch between these two hills was not low enough to give each sufficient drop to be listed as separate summits; only Bryn yr Ŵyn was previously listed.  This Trimble survey confirms Bryn Llwyd to be the higher summit (see Summit Relocation post) and as the nearest paved public road at SN 84696 94288 is 2.525km from the summit this hill qualifies for the listing of Y Pellennig – The Remotest Hills of Wales, having the required 15m minimum drop and 2.5km minimum distance between the summit and the nearest paved public road.

This now brings the overall total for Y Pellennig to 168 hills for the Complete list (All Wales), with the total for the Mainland Wales list being 124 hills.  The Master List will be duly updated on the Mapping Mountains site.


The full details for the hill are:


Cardinal Hill:  Pumlumon Fawr

Summit Height:  501.4m (converted to OSGM15, and average of four summit surveys)

Name:  Bryn Llwyd

OS 1:50,000 map:  135, 136

Summit Grid Reference:  SN 83574 92022

Drop:  30.3m (converted to OSGM15)

Distance:  2.525km


The list of additions and deletions in the Pellennig list since the 1st edition of Y Pellennig – The Remotest Hills of Wales was published by Europeaklist is as follows:


ADDITIONS



Bryn Llwyd (SN 835 920) 1st survey2nd survey



DELETIONS




Bryn Llwyd (SN 835 920) now confirmed as a Pellennig hill

For details on the 1st Trimble survey and the 2nd Trimble survey that promoted this hill to Pellennig status.


Myrddyn Phillips and Aled Williams (May 2016)






Mapping Mountains - Hill Reclassifications - Y Pellennig - The Remotest Hills of Wales

Graig Fach (SN 821 931) - Pellennig deletion (3rd reclassification)

Survey post for Graig Fach


There has been a deletion of a hill from the list of Y Pellennig – The Remotest Hills of Wales, due to a survey with the Trimble.  The hill is situated in the Pumlumon group in northern mid Wales and is situated between the towns of Machynlleth to its north-west and Llanidloes to its south-east with the mountain lakes of Glaslyn to its north and Bugeilyn to its south.

The hill was surveyed on 5th May 2016 in beautiful early morning sunshine and its name is Graig Fach.  It can be easily accessed from the north via the track that leaves a minor road toward the lake of Glaslyn, or alternatively a longer approach to the hill is from the south-west following the path above the course of the Afon Hengwm. 

Graig Fach has a 514m summit spot height and bwlch contouring between 490m – 500m with a 499m spot height appearing on the Ordnance Survey enlarged mapping on the Geograph website, this latter spot height is positioned on the track and interpolation suggests that it is not positioned where the critical bwlch is situated.

The bwlch consists of moor grass and heather and two data sets were taken, both within a few metres of one another, whilst the summit consists of moor grass and again, two data sets were taken resulting in the hill only having 14.5m of drop and therefore below the 15m minimum drop value required to qualify for the list.  This hill is a loss for the Pellennig listing as it is one that must be seldom visited and affords good views across to the expanse of wilderness situated around Llechwedd Crin and Banc Bugeilyn.

This now brings the overall total for Y Pellennig to 167 hills for the Complete list (All Wales), with the total for the Mainland Wales list also decreasing by one to 123 hills.  The Master List will be duly updated on the Mapping Mountains site.


The full details for the hill are:

Cardinal Hill:  Foel Fadian

Summit Height:  513.1m (converted to OSGM15)

Name:  Graig Fach

OS 1:50,000 map:  135, 136

Summit Grid Reference:  SN 821 931

Drop:  14.5m (converted to OSGM15)


The list of additions and deletions in the Pellennig list since the 1st edition of Y Pellennig – The Remotest Hills of Wales was published by Europeaklist is as follows:


ADDITIONS





DELETIONS




Graig Fach (SN 821 931) now deleted from the Y Pellennig list



Myrddyn Phillips and Aled Williams (May 2016)






Mapping Mountains - Hill Reclassifications - Y Pellennig - The Remotest Hills of Wales

Ynys Arw (SH 266 945) - Pellennig addition (2nd reclassification)

Survey post for Ynys Arw

Significant Height Revisions post for Ynys Arw 


There has been a new hill that has entered the list of Y Pellennig – The Remotest Hills of Wales, due to a recent Trimble survey.  The hill is situated on Ynysoedd y Moelrhoniaid, this small group of islands are positioned to the north-west, off the north-west coast of Ynys Môn; its name is Ynys Arw.

Ynys Arw (SH 266 945) is the most south-westerly island of this archipelago and has two high points, with the more southerly of these being the highest.  Ynys Arw is tidal and is connected by land to its higher neighbour at low tide, the higher island is where The Skerries Lighthouse is situated and is the highest point of the archipelago and is also listed as a Pellennig hill.

The summit of Ynys Arw is easily accessed at low tide from the Lighthouse, although hands on rock are required to get down to the connecting land that is submerged at high tide.  The ascent from this wet sea weeded land is on rock and then grass that has a multitude of burrowed Tern nests excavated into it.

The high point of Ynys Arw has a 10m ring contour on it and no spot height on current Ordnance Survey maps, it was surveyed with the Trimble GeoXH 6000 at being 15.2m (converted to OSGM15) high, and as the criteria for qualification to the Pellennig list is a hill whose summit is a minimum of 2.5 km from the nearest paved public road and which has a minimum drop of 15m, this hill easily qualifies on the distance criterion and now meets the necessary minimum drop criterion to become the latest entry to the Pellennig list.

This now brings the overall total for Y Pellennig to 168 hills for the Complete list (All Wales), with the total for the Mainland Wales list remaining the same at 124 hills.  The Master List will be duly updated on the Mapping Mountains site.


The full details for the hill are:

Cardinal Island:  Ynysoedd y Moelrhoniaid

Summit Height:  15.2m (converted to OSGM15)

Name:  Ynys Arw

OS 1:50,000 map:  114

Summit Grid Reference:  SH 266 945

Drop:  15.2m (converted to OSGM15)


The list of additions in the Y Pellennig list since the 1st edition of Y Pellennig – The Remotest of Wales was published by Europeaklist is as follows:


ADDITIONS


Ynys Arw (SH 266 945)


Ynys Arw (SH 266 945) - the new Pellennig hill

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

Myrddyn Phillips and Aled Williams (September 2015)







Mapping Mountains - Hill Reclassifications - Y Pellennig - The Remotest Hills of Wales


Pen Diban (SH 112 205) - Pellennig addition (1st reclassification)

Survey post for Pen Diban


There has been a re-instatement of a Pellennig hill due to a recent Trimble survey.  The hill is situated on Ynys Enlli and is positioned at the south of the island; its name is Pen Diban.

Pen Diban (SH 112 205) was included in the original list of Y Pellennig that was published on Geoff Crowder’s v-g.me website and listed with a 20m high summit and a c 5m high bwlch, giving a drop of c 15m.  The drop was estimated and based on contour interpolation with the Ordnance Survey 1:25,000 paper maps having 10m contour intervals.
Since the original publication of Y Pellennig, the Ordnance Survey enlarged mapping on the Geograph website has become available; this mapping for the area where Pen Diban is situated gives contour intervals at 5m and narrows the area and the height of the bwlch to c 5m – c 10m.  Therefore the drop of Pen Diban was re-evaluated as c 14m and it was deleted from the ranks of Y Pellennig – The Remotest Hills of Wales.

This hill has now been surveyed with the Trimble GeoXH 6000, its surveyed summit height is 20.0m (converted to OSGM15) and its surveyed bwlch height is 5.0m (converted to OSGM15).


The raw processed survey result for the summit is 19.975m converted to OSGM15

The raw processed survey result for the bwlch is 4.982m converted to OSGM15

The margin of uncertainty for the height in relation to the position of the Trimble on the summit is 0.0m and for the bwlch 0.05m.

The precision of the equipment is +/- 0.15m.

The accuracy of the equipment is 0.1m.

Therefore the raw result for the drop should be rounded to one decimal place; 15.0m


This now brings the overall total for Y Pellennig to 167 hills for the Complete list (All Wales), with the total for the Mainland Wales list remaining the same at 124 hills.  The Master List will be duly updated on the Mapping Mountains blog.


The full details for the hill are:

Cardinal Island:  Ynys Enlli

Summit Height:  20.0m (converted to OSGM15)

Name:  Pen Diban

OS 1:50,000 map:  123

Summit Grid Reference:  SH 112 205

Drop:  15.0m (converted to OSGM15)


Pen Diban (SH 112 205) the re-instated Pellennig hill

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

Myrddyn Phillips and Aled Williams (April 2015)


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