Tuesday, 4 July 2017

Mapping Mountains – Hill Reclassifications – Y Trechol – The Dominant Hills of Wales


Y Trechol – The Dominant Hills of Wales – Hill Reclassifications

Y Trechol –The Dominant Hills of Wales are the Welsh P30 hills whose prominence equal or exceed half that of their absolute height, accompanying the Dominant list is a sub list entitled The Lesser Dominant Hills of Wales with the criteria for this sub category being those additional Welsh P30 hills whose prominence is between one third and half that of their absolute height.  The list commenced publication on Mapping Mountains on 03.012.15 with its initial Introduction giving details to its compilation and criteria.  

The list is authored by Myrddyn Phillips and the posts that have appeared on Mapping Mountains detailing the additions, reclassifications and deletions to the Dominant and Lesser Dominant list appear below presented chronologically in receding order.









Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Bryn Mawr (SJ 251 190) – Lesser Dominant reclassified to Dominant (26th reclassification)

Survey post for Bryn Mawr

Significant Height Revisions post for Bryn Mawr


There has been a reclassification to the listing of Y Trechol – The Dominant Hills of Wales; resulting in this hill being reclassified from a Lesser Welsh Dominant to a Dominant hill.  With the criteria for inclusion to the Dominant list being those Welsh P30 hills whose prominence equal or exceed half that of their absolute height.

The details relating to this hill’s inclusion as a Dominant hill are retrospective as its reclassification was dependent upon a survey with the Trimble GeoXH 6000 which was conducted on the 8th August 2015, with its details appearing in the Carnedd Wen group of hills when published on the Mapping Mountains site on the 3rd June 2017.

Prior to this hill’s inclusion as a Dominant hill it was listed as a Lesser Welsh Dominant hill with 49.13% Dominance based on an estimated c 173m summit height and an estimated bwlch height of c 88m, which gave this hill c 85m of drop.  The bwlch height was later revised to 88m based on the spot height that appears on the Ordnance Survey enlarged mapping hosted on the Geograph website; this revision did not alter this hill’s Dominance value.

The hill is listed in the Carnedd Wen group and is placed in the Region of North Wales (Region A, Sub-Region A4) with its Cardinal Hill being Y Golfa (SJ 182 070), and is situated above the B 4393 road which is to its north and east and the A 483 road to its south-east, and has the Montgomery Canal to its east and the Afon Efyrnwy (River Vyrnwy) to its north, and is positioned between the small communities of Llansantffraid-ym-Mechain to the west north-west, Llanymynech to the north-east, Four Crosses to the east south-east and Ardllin (Arddleen) towards the south.

As the hill is not a part of designated open access land permission to visit should be sought, with the nearest public footpath situated to the north-east of the summit, which consists of overgrown undergrowth and trees.

The name of the hill is Bryn Mawr and it qualifies for Dominant status based on the survey with the Trimble GeoXH 6000 resulting in a summit height of 178.1m (converted to OSGM15) which when coupled with its 88m bwlch spot height gives this hill 90m of drop and 50.53% Dominance.
  

The full details for the hill are:

Group:  Carnedd Wen

Name:  Bryn Mawr

Dominance:  50.53%

OS 1:50,000 map:  126

Summit Grid Reference:  SJ 25117 19054

Summit Height:  178.1m (converted to OSGM15)

Drop Summit to Bwlch:  90m

Drop Bwlch to ODN:  88m 


Bryn Mawr (SJ 251 190) now reclassified to a Dominant hill



Myrddyn Phillips (July 2017)






Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Carn Ysgubor (SM 699 246) – Dominant reclassified to Lesser Dominant (25th reclassification)

Survey post for Carn Ysgubor


Please note; Carn Ysgubor was originally listed as a Lesser Dominant based on map detail, it was then reclassified to a Dominant based on a survey with the Trimble GeoXH 6000, since this survey the Ordnance Survey have adopted OSGM15, this remodelling has altered the known accurate height of Welsh hills by approximately 2-4cm, and the conversion to OSGM15 of data produced by the Trimble for Carn Ysgubor has resulted in this hill being reclassified back to the ranks of Lesser Dominant hills.


There has been a reclassification to the listing of Y Trechol – The Dominant Hills of Wales which has resulted in this hill being reinstated to The Lesser Dominant Hills of Wales list due to a survey with the Trimble GeoXH 6000 and the subsequent conversion of these data to OSGM15. 

The details relating to this hill’s reclassification and reinstatement as a Lesser Welsh Dominant are retrospective as the survey with the Trimble GeoXH 6000 took place on the 15th May 2016 and the conversion of data to OSGM15 was instigated on Mapping Mountains shortly after 30th August 2016.

The criteria for Dominant status are those Welsh P30s whose prominence equal or exceed 50% of their absolute height, whilst the criteria for Lesser Dominant status are those additional Welsh P30s whose prominence is 33% or more and below 50% of their absolute height.

The hill was originally listed as a Lesser Dominant with 49.50% Dominance based on the 101m summit spot height that appears on Ordnance Survey 1:25,000 Explorer maps and an estimated bwlch height of c 51m, with these values giving the hill c 50m of drop. 

The hill was subsequently reclassified to a Dominant with 50.00% Dominance based on a survey with the Trimble GeoXH 6000 resulting in a 102.4m (102.369m) summit height and a 51.2m (51.182m) bwlch height, with these values giving this hill 51.2m (51.187m) of drop and 50.00244% of Dominance.

The hill is listed in the Pembrokeshire Islands group and is placed in the Region of Mid and West Wales (Region B, Sub-Region B4) with its Cardinal Island being Ynys Dewithe hill is positioned on the northern part of Ynys Dewi, this island is also commonly known as Ramsey, and is situated to the west of St David’s in the south-west of Wales.

As the hill is situated on an island the only way to approach is via boat and the only company with permission to land on Ynys Dewi is Thousand Island Adventures (tel: 01437-721721).  The hill can be easily accessed from where the boat docks as a gravelled track leads up to The Farmhouse from where a vehicle path heads toward The Bungalow, which is a house on the eastern slopes of the hill.  A narrower path leaves this main route and heads toward the summit of the hill.

The name of the hill is Carn Ysgubor, with its composition presented as Carnysgubor on current Ordnance Survey maps, and it has been reclassified and reinstated to The Lesser Dominant Hills of Wales list as the conversion using OSGM15 has resulted in an increase of 0.026m in both its summit and bwlch heights as surveyed using the Trimble GeoXH 6000, with the summit height amended from 102.369m to 102.395m and the bwlch height amended from 51.182m to 51.208m.  The increase in heights has also affected the Dominance of the hill from 50.00% to 49.99% and therefore Carn Ysgubor is reclassified from a Dominant to a Lesser Dominant hill.  

Carn Ysgubor is only the third hill that I know of whose status has been altered due to the Ordnance Survey remodelling known as OSGM15.  This remodelling has increased the accurately known height of hills in Wales by approximately 2-4cm, and the other two hills whose status has been altered through the conversion to OSGM15 are Calf Top (SD 664 856) and Pen y Gaer (SO 139 976).



The full details for the hill are:

Group:  Pembrokeshire Islands

Name:  Carn Ysgubor

Dominance:  49.99%

OS 1:50,000 map:  157

Summit Grid Reference:  SM 69953 24603

Summit Height:  102.4m (converted to OSGM15)

Drop Summit to Bwlch:  51.2m

Drop Bwlch to ODN:  51.2m (converted to OSGM15) 


Carn Ysgubor (SM 699 246) has now been reclassified and reinstated to the Lesser Dominant list due to a survey with the Trimble GeoXH 6000 and the conversion of data to OSGM15



Myrddyn Phillips (July 2017)






Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Pt. 259m (SJ 181 438) – Lesser Dominant addition (24th reclassification)


There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales which has resulted in this hill being added to the Lesser Welsh Dominant list.  The criteria for inclusion in this category of sub list is those P30 hills whose prominence is 33% or more and below 50% of their absolute height.

The details relating to this hill’s inclusion as a Lesser Welsh Dominant are retrospective as it appeared in the Y Berwyn group of hills when published on the Mapping Mountains site on the 3rd March 2017.

The hill did not appear in the original listing of Y Trechol – The Dominant Hills of Wales as it was listed with an estimated c 86m of drop, and when coupled with its 259m summit spot height that appeared on the Ordnance Survey 1:25,000 Explorer map it gave this hill 33.20% Dominance, which was just under the minimum required to be classified as a Lesser Welsh Dominant hill.

The hill is listed in the Y Berwyn group and is placed in the Region of North Wales (Region A, Sub-Region A4) with its Cardinal Hill being Moel Fferna (SJ 116 397), and is almost encircled by the Afon Dyfrdwy (River Dee) and is situated with the town of Llangollen to the east south-east.

If wanting to visit the hill the upper section is a part of designated open access land and it can be easily accessed from a track that leaves the A5 road which is positioned to the south of the summit.

The hill is being listed under the point (Pt. 259m) notation as I do not know an appropriate name for it either from local enquiry or historical research, and it qualifies for Lesser Welsh Dominant status based on a re-interpolation of its bwlch height which gives the hill a drop of 87m and a Dominance of 33.59%.


The full details for the hill are:

Group:  Y Berwyn

Name:  Pt. 259m

Dominance:  33.59%

OS 1:50,000 map:  125

Summit Grid Reference:  SJ 18114 43816

Summit Height:  259m

Drop Summit to Bwlch:  87m

Drop Bwlch to ODN:  172m 


Myrddyn Phillips (June 2017)






Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Pt. 258m (SH 647 065) – Lesser Dominant addition (23rd reclassification)


There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales which has resulted in this hill being added to the Lesser Welsh Dominant list.  The criteria for inclusion in this category of sub list is those Welsh P30 hills whose prominence is 33% or more and below 50% of their absolute height.

The details relating to this hill’s inclusion as a Lesser Welsh Dominant hill are retrospective as it appeared in the Tarennydd group of hills when published on the Mapping Mountains site on the 3rd December 2016.

The hill did not appear in the original listing of Y Trechol – The Dominant Hills of Wales as bwlch contours on Ordnance Survey maps of the day implied that the drop for the hill was only c 81m, with this based on the 258m summit spot height and an estimated bwlch height of 177m based on interpolation of bwlch contouring between 170m – 180m, these values would give the hill 31.40% Dominance which is insufficient for it to qualify for this sub list.

The hill is listed in the Tarennydd group and is placed in the Region of North Wales (Region A, Sub-Region A3) with its Cardinal Hill being Foel Wyllt (SH 624 042), and it is situated with the village of Abergynolwyn to its east and it rises above Dyffryn Dysynni and the Afon Dysynni which are to its north-west.

The hill is adjacent to Craig yr Aderyn (Bird’s Rock) and makes a good small circuit with its lower heighted neighbour, with both summits situated on designated open access land and public footpaths connecting with their summits from the valleys towards the north, west and east.

The hill is being listed under the point (Pt. 258m) notation as I do not know an appropriate name for it either from local enquiry or historical research, and it qualifies for Lesser Welsh Dominant status based on the 171m bwlch spot height that appears on the Ordnance Survey enlarged mapping hosted on the Geograph website, this when coupled with its 258m summit spot height gives the hill 87m of drop and 33.72% Dominance.


The full details for the hill are:

Group:  Tarennydd

Name:  Pt. 258m

Dominance:  33.72%

OS 1:50,000 map:  124

Summit Grid Reference:  SH 64705 06587

Summit Height:  258m

Drop Summit to Bwlch:  87m

Drop Bwlch to ODN:  171m 


Myrddyn Phillips (May 2017)






Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Pt. 119m (SH 721 004) – Lesser Dominant reclassified to Dominant (22nd reclassification)


There has been a reclassification to the listing of Y Trechol – The Dominant Hills of Wales; this has resulted in this hill being reclassified from a Lesser Welsh Dominant to a Dominant hill.  With the criteria for inclusion to the Dominant list being all Welsh P30 hills whose prominence equal or exceed half that of their absolute height.

The details relating to this hill’s inclusion as a Dominant hill are retrospective as it appeared in the Tarennydd group of hills when published on the Mapping Mountains site on the 3rd December 2016.

Prior to this hill’s inclusion as a Dominant hill it was listed as a Lesser Welsh Dominant hill with 48.25% Dominance based on an estimated c 114m summit height and a 59m bwlch spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps, which gave this hill c 55m of drop.

The hill is listed in the Tarennydd group and is placed in the Region of North Wales (Region A, Sub-Region A3) with its Cardinal Hill being Tarren y Gesail (SH 710 058), and it is situated between the A 493 road to its north and the Afon Dyfi (River Dovey) and the A 487 road to its south with the town of Machynlleth to its east north-east.

There are tracks leading from the valley up the hill to the north and east of the summit, but as the hill is not situated on a part of designated open access land permission to visit should be sought.

The hill is being listed under the point (Pt. 119m) notation as I do not know an appropriate name for it either from local enquiry or historical research, and it qualifies for Dominant status based on the 119m summit spot height that appears on the Ordnance Survey enlarged mapping hosted on the Geograph website, this when coupled with its 59m bwlch spot height gives the hill 60m of drop and 50.42% Dominance.

  

The full details for the hill are:

Group:  Tarennydd

Name:  Pt. 119m

Dominance:  50.42%

OS 1:50,000 map:  135

Summit Grid Reference:  SH 72136 00406

Summit Height:  119m

Drop Summit to Bwlch:  60m

Drop Bwlch to ODN:  59m 


Myrddyn Phillips (May 2017)







Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Coed y Garth (SH 661 165) – Lesser Dominant addition (21st reclassification)


There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales which has resulted in the hill being added to the Lesser Welsh Dominant list.  The criteria for inclusion in this category of sub list is those P30 hills whose prominence is 33% or more and below 50% of their absolute height.

The details relating to this hill’s inclusion as a Lesser Welsh Dominant hill are retrospective as it appeared in the Cadair Idris group of hills when published on the Mapping Mountains site on the 3rd November 2016.

The hill did not appear in the original listing of Y Trechol – The Dominant Hills of Wales as Ordnance Survey maps only gave the summit of the hill as having an uppermost ring contour of 80m, and with bwlch contouring between 50m – 60m the drop had been estimated as being below the minimum of 30m required for consideration for this list.

Since this list’s inception online mapping has improved and it is details on the Ordnance Survey enlarged mapping hosted on the Geograph website combined with the Harvey 1:25,000 Cadair Idris Superwalker map that has both bwlch and summit spot heights for this hill, with the former being 56m and the latter 87m, with these values giving 31m of drop and 35.63% Dominance.

The hill is listed in the Cadair Idris group and is placed in the Region of North Wales (Region A, Sub-Region A3) with its Cardinal Hill being Cadair Idris (SH 711 130), and it is situated between the small communities of Arthog to the south-west and Abergwynant to the east north-east.

As the hill is situated in conifer plantation a route to its summit may prove problematic, with access from the track that crosses its bwlch to the north-east possibly offering the quickest approach.

The name of the hill is Coed y Garth and it qualifies for Lesser Welsh Dominant status based on the 87m summit spot height on the Harvey 1:25,000 Cadair Idris Superwalker map and the 56m bwlch spot height on the Ordnance Survey enlarged mapping hosted on the Geograph website, with these values giving this hill 31m of drop and 35.63% Dominance.
   

The full details for the hill are:

Group:  Cadair Idris

Name:  Coed y Garth

Dominance:  35.63%

OS 1:50,000 map:  124

Summit Grid Reference:  SH 66100 16583

Summit Height:  87m

Drop Summit to Bwlch:  31m

Drop Bwlch to ODN:  56m


Myrddyn Phillips (May 2017)







Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Ynys Glog (SH 596 398) - Dominant addition (20th reclassification)

Survey post for Ynys Glog


There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales due to detail included on the Ordnance Survey enlarged mapping hosted on the Geograph website and which was first spotted by Aled Williams.  This has resulted in the hill being added to the Dominant list.  With the criteria for inclusion to this list being those Welsh P30 hills whose prominence equal or exceed half that of their absolute height.

The details relating to this hill’s inclusion as a Dominant hill are retrospective as it was added to the list shortly after Aled first proposed it as a new P30 in February 2014, and later appeared in the Moelwynion group of Dominant hills when published on Mapping Mountains on the 25th February 2016.

Prior to Aled proposing this hill as a new P30 and its subsequent inclusion as a Dominant hill, it was not classified as contouring on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map implied that the hill did not have the required minimum 30m of drop to be considered for P30 and Dominant status.

The hill is in the Moelwynion group of hills and is placed in the Region of North Wales (Region A, Sub-Region A1) and is situated between the towns of Porthmadog to the west south-west and Penrhyndeudraeth to the east south-east.

The hill is not on open access land and therefore permission to visit should be sought.  For those wishing to do so the ascent is through undergrowth next to stunted deciduous trees to a summit which is slightly laid back from a large drop to fields below.

The name of the hill is Ynys Glog, and it was included as a Dominant hill based on detail from the Ordnance Survey enlarged mapping hosted on the Geograph website which gives the hill a 42m summit spot height and bwlch contouring between 5 – 10m, with an estimated bwlch height of c 8m, these values gave the hill c 34m of drop and 80.95% Dominance.  The hill has subsequently been surveyed using the Trimble GeoXH 6000 resulting in a 40.6m (converted to OSGM15) summit height and a 7.9m (converted to OSGM15) bwlch height, giving this hill 32.7m of drop and 80.44% Dominance.


The full details for the hill are:

Group:  Moelwynion

Name:  Ynys Glog

Dominance:  80.44%

OS 1:50,000 map:  124

Summit Grid Reference:  SH 59647 39826

Summit Height:  40.6m (converted to OSGM15)

Drop Summit to Bwlch:  32.7m

Drop Bwlch to ODN:  7.9m (converted to OSGM15) 


Ynys Glog (SH 596 398) now listed as a Dominant hill



Myrddyn Phillips (April 2017)







Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Ynys Berfedd (SH 599 398) - Dominant addition (19th reclassification)

Survey post for Ynys Berfedd


There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales due to detail included on the Ordnance Survey enlarged mapping hosted on the Geograph website and which was first spotted by Aled Williams.  This has resulted in the hill being added to the Dominant list.  With the criteria for inclusion to this list being those Welsh P30 hills whose prominence equal or exceed half that of their absolute height.

The details relating to this hill’s inclusion as a Dominant hill are retrospective as it was added to the list shortly after Aled first proposed it as a new P30 in February 2014, and later appeared in the Moelwynion group of Dominant hills when published on Mapping Mountains on the 25th February 2016.

Prior to Aled proposing this hill as a new P30 and its subsequent inclusion as a Dominant hill, it was listed in the sub list that accompanied the Welsh P30 lists that were published on Geoff Crowder’s v-g.me website with a c 30m summit height, and not in the main P30 list as the contouring on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map implied that the hill did not have the required minimum 30m of drop to be considered for Dominant status.

The hill is in the Moelwynion group of hills and is placed in the Region of North Wales (Region A, Sub-Region A1) and is situated between the towns of Porthmadog to the west south-west and Penrhyndeudraeth to the south-east.

The hill is not on open access land and therefore permission to visit should be sought.  For those wishing to do so the ascent is next to stunted deciduous trees and on moss covered rocks to a summit overlooking a vertical drop to the north.

The name of the hill is Ynys Berfedd, and it was included as a Dominant hill based on detail from the Ordnance Survey enlarged mapping hosted on the Geograph website which gives the hill a 43m summit spot height and bwlch contouring between 0 – 10m, with an estimated bwlch height of c 6m, these values gave the hill c 37m of drop and 86.05% Dominance.  The hill has subsequently been surveyed using a Trimble GeoXH 6000 resulting in a 42.9m (converted to OSGM15) summit height and a 6.8m (converted to OSGM15) bwlch height, giving this hill 36.1m of drop and 84.06% Dominance.


The full details for the hill are:

Group:  Moelwynion

Name:  Ynys Berfedd

Dominance:  84.06%

OS 1:50,000 map:  124

Summit Grid Reference:  SH 59943 39865

Summit Height:  42.9 (converted to OSGM15)

Drop Summit to Bwlch:  36.1m

Drop Bwlch to ODN:  6.8m (converted to OSGM15) 


The Trimble GeoXH 6000 gathering data at the summit of Ynys Berfedd



Myrddyn Phillips (April 2017)






Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Ynys Gron (SH 596 392) - Dominant deletion (18th reclassification)

Survey post for Ynys Gron


There has been a deletion to the listing of Y Trechol – The Dominant Hills of Wales due to detail included on current Ordnance Survey maps.  This has resulted in the hill being taken out of the Dominant list.  With the criteria for inclusion to this list being those Welsh P30 hills whose prominence equal or exceed half that of their absolute height.

The details relating to this hill’s deletion as a Dominant hill are retrospective as it did not appear in the Moelwynion group of hills when published on Mapping Mountains on the 25th February 2016.

The hill had been listed in the original Welsh P30 lists when published on Geoff Crowder’s v-g.me website with a 96m summit height based on the Ordnance Survey 1:25,000 Outdoor Leisure spot height, with an accompanying note stating ‘98m on 1984 1:50,000 map.  Summit being reduced due to quarrying’.  When drop values were added to the P30 Master Lists this hill was given an estimated drop of c 50m which gave the hill 52.08% Dominance, and therefore it was included in the original listing of Y Trechol – The Dominant Hills of Wales.

The hill is in the Moelwynion group of hills and is placed in the Region of North Wales (Region A, Sub-Region A1) and is situated between the towns of Porthmadog to the west and Penrhyndeudraeth to the east, and immediately above the busy A 487 road which is to its south.

The hill is not on open access land and its whole south-western part forms the Garth Quarry, which is operational, because of this permission to visit should be sought.  However, the approach from the east is through woodland and would take a visitor direct to the remaining high point of the hill.

The name of the hill is Ynys Gron, which is a locally known name and it has been deleted from the Dominant list as the quarry has now obliterated the upper 30m of the hill and reduced it in height to 69.4m (converted to OSGM15), and as its bwlch has been surveyed as 44.3m (converted to OSGM15) in height, it gives this hill only 25.1m of drop, which is insufficient for it to be considered for Dominant status.


The full details for the hill are:

Group:  Moelwynion

Name:  Ynys Gron

Dominance:  N/A

OS 1:50,000 map:  124

Summit Grid Reference:  SH 59653 39268

Summit Height:  69.4m (converted to OSGM15)

Drop Summit to Bwlch:  25.1m

Drop Bwlch to ODN:  44.3m (converted to OSGM15) 


The view west from the summit of Ynys Gron



Myrddyn Phillips (April 2017)






Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Moel y Penmaen (SH 338 386) - Lesser Dominant addition (17th reclassification)


There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales which has resulted in the hill being added to the Lesser Welsh Dominant list.  The criteria for inclusion in this category of sub list is those Welsh P30 hills whose prominence is 33% or more and below 50% of their absolute height.

The details relating to this hill’s inclusion as a Lesser Welsh Dominant hill are retrospective as it appeared in the Pen Llŷgroup of hills when published on the Mapping Mountains site on the 11th February 2016.

The hill did not appear in the original listing of Y Trechol – The Dominant Hills of Wales even though the details on the then current Ordnance Survey maps showed a 153m summit spot height and bwlch contours between 90m – 100m, with an estimated bwlch height of c 92m giving a drop of c 61m and a Dominance of 39.87% which is sufficient for inclusion into the Lesser Welsh Dominant list.

The hill is listed in the Pen Llŷgroup and is placed in the Region of North Wales (Region A, Sub-Region A1) with its Cardinal Hill being Garn Ganol (SH 364 447), and it is situated between the small communities of Boduan to the south-west and Llannor to the south-east.

If wanting to visit the hill a track to the south-east which makes its way toward a small reservoir gives easy access to the upper part of the hill which is on open access land.

The name of the hill is Moel y Penmaen and it qualifies for Lesser Welsh Dominant status based on a 153m summit and a c 92m bwlch height, with these values giving this hill c 61m of drop and 39.87% of Dominance.


The full details for the hill are:

Group:  Pen Llŷn

Name:  Moel y Penmaen

Dominance:  39.87%

OS 1:50,000 map:  123

Summit Grid Reference:  SH 33810 38687

Summit Height:  153m

Drop Summit to Bwlch:  c 61m

Drop Bwlch to ODN:  c 92m 


Myrddyn Phillips (March 2017)







Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Pt. c 71m (SH 310 297) - Lesser Dominant addition (16th reclassification)


There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales due to detail included on the Ordnance Survey enlarged mapping hosted on the Geograph website.  This has resulted in the hill being added to the Lesser Welsh Dominant list.  The criteria for Lesser Welsh Dominant status is those P30 hills whose prominence is 33% or more and below 50% of their absolute height.

The details relating to this hill’s inclusion as a Lesser Welsh Dominant hill are retrospective as it appeared in the Pen Llŷgroup of hills when published on the Mapping Mountains site on the 11th February 2016.

Prior to this hill’s inclusion as a Lesser Welsh Dominant hill it was listed with c 25m of drop which is insufficient for consideration to this sub category of hill, with this drop value based on an estimated summit height of c 71m based on the size of the uppermost 70m ring contour on Ordnance Survey maps in comparison to the size of contours below it, and an estimated bwlch height of c 46m based on bwlch contouring between 40m – 50m that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps.   

The hill is listed in the Pen Llŷgroup and is placed in the Region of North Wales (Region A, Sub-Region A1) with its Cardinal Hill being Garn Fadrun (SH 278 351), and it is situated between the small communities of Llanbedrog to the north-east, Mynytho to the north-west and Abersoch to the south.

If wanting to visit the hill permission to do so should be sought as the summit area is not a part of open access land, however the hill has a number of public footpaths encircling it that start from the A 499 road to its east and the network of minor roads to its north and west.

The hill is being listed by the point (Pt. c 71m) notation as an appropriate name either known locally or from historical research has not been found by the author, although when the hill was first included in the P30 Welsh lists that appeared on Geoff Crowder’s v-g.me website it was by an invented name of Castellmarch, this name was taken from buildings situated to the east of the summit.

It is included as a Lesser Welsh Dominant hill as the Ordnance Survey enlarged mapping hosted on the Geograph website has contours at 5m intervals giving the hill a 41m bwlch spot height with bwlch contouring between 40m – 45m, as opposed to the previously estimated bwlch height of c 46m based on the 40m – 50m bwlch contouring on the 1:25,000 Explorer map.  With an estimated c 71m summit height and a 41m bwlch height it gives this hill c 30m of drop which is sufficient for consideration to the Dominant list, and as these values give this hill 42.25% Dominance it is now listed as a Lesser Welsh Dominant hill.


The full details for the hill are:

Group:  Pen Llŷn

Name:  Pt. c 71m

Dominance:  42.25%

OS 1:50,000 map:  123

Summit Grid Reference:  SH 31034 29730

Summit Height:  c 71m

Drop Summit to Bwlch:  c 30m

Drop Bwlch to ODN:  41m 


Myrddyn Phillips (March 2017)







Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Carreglefain (SH 324 410) - Lesser Dominant reclassified to Dominant (15th reclassification)

Survey post for Carreglefain


There has been a reclassification to the listing of Y Trechol – The Dominant Hills of Wales due to a survey with the Trimble GeoXH 6000.  This has resulted in the hill being reclassified from a Lesser Welsh Dominant to a Dominant hill.  With the criteria for inclusion to this list being those Welsh P30 hills whose prominence equal or exceed half that of their absolute height.

The details relating to this hill’s inclusion as a Dominant hill are retrospective as it appeared in the Pen Llŷn group of hills when published on the Mapping Mountains site on the 11th February 2016.

Prior to this hill’s inclusion as a Dominant hill it was listed as a Lesser Welsh Dominant hill with 48.66% Dominance based on its 261m summit spot height that appears on Ordnance Survey 1:25,000 Explorer maps and a c 127m drop based on bwlch contouring between 130m – 140m with an estimated bwlch height of c 134m.

The hill is listed in the Pen Llŷgroup and is placed in the Region of North Wales (Region A, Sub-Region A1) with its Cardinal Hill being Garn Ganol (SH 278 351), and it is situated between the small communities of Nefyn towards the west and Llithfaen to the north-east.

If wanting to visit the hill it can be accessed from a number of directions via public footpaths that lead to open access land that takes in the supper section of the hill.

The name of the hill is Carreglefain and the Trimble survey that resulted in its reclassification was conducted by Myrddyn Phillips on the 24th November 2014 resulting in a 260.7m (converted to OSGM15) summit height and a 130.1m (converted to OSGM15) bwlch height, with these values giving this hill 130.6m of drop and 50.08% of Dominance.



The full details for the hill are:

Group:  Pen Llŷn

Name:  Carreglefain

Dominance:  50.08%

OS 1:50,000 map:  123

Summit Grid Reference:  SH 32421 41054

Summit Height:  260.7m (converted to OSGM15)

Drop Summit to Bwlch:  130.6m

Drop Bwlch to ODN:  130.1m (converted to OSGM15) 


Carreglefain (SH 324 410) now reclassified from a Lesser Welsh Dominant to a Dominant hill


Myrddyn Phillips (March 2017)





Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Pt. 66m (SH 299 270) - Lesser Dominant reclassified to Dominant (14th reclassification)


There has been a reclassification to the listing of Y Trechol – The Dominant Hills of Wales due to detail included on the Ordnance Survey enlarged mapping hosted on the Geograph website.  This has resulted in the hill being reclassified from a Lesser Welsh Dominant to a Dominant hill.  With the criteria for inclusion to this list being those Welsh P30 hills whose prominence equal or exceed half that of their absolute height.

The details relating to this hill’s inclusion as a Dominant hill are retrospective as it appeared in the Pen Llŷgroup of hills when published on the Mapping Mountains site on the 11th February 2016.

Prior to this hill’s inclusion as a Dominant hill it was included as a Lesser Welsh Dominant hill based on its summit position being at SH 295 266 where the 64m spot height appears on Ordnance Survey 1:25,000 Explorer maps, with its listed drop being c 31m based on an estimated bwlch height of c 33 and a Dominance of 48.44%, importantly this map showed a 60m ring contour to the north-east of this summit, but with no spot height the 64m map heighted summit was listed as the Lesser Welsh Dominant hill.

In more recent years the Ordnance Survey enlarged mapping hosted on the Geograph website has been made publicly available and this scale of mapping shows many spot heights not on any other publicly available map, and the 60m ring contour to the north-east of the 64m map heighted summit is given a 66m summit spot height on this more detailed and larger scaled map, and therefore the summit position of this hill has changed to the higher map heighted hill and because of this the drop value and Dominance of the hill has also altered, and it is now listed with a 66m summit and 32m bwlch height, with both spot heights taken from the enlarged map on the Geograph website.  These values give the hill 34m of drop and 51.52% Dominance.

The hill is in the Pen Llŷgroup of hills and is placed in the Region of North Wales (Region A, Sub-Region A1) with its Cardinal Hill being Garn Fadrun (SH 278 351), and it is situated with the small community of Llanengan to the west and the small town of Abersoch to the north-east.

If wanting to visit the hill it can be easily ascended as it is near a number of minor roads, however its summit is not a part of open access land so permission to visit should be sought.

The hill is being listed by the point (Pt. 66m) notation as an appropriate name either known locally or from historical research has not been found by the author, although when the old summit was first listed in the sub list that accompanied the P30 Welsh lists that appeared on Geoff Crowder’s v-g.me website it was listed by an invented name of Bryn Llanengan, named after the village to the north-west of the old summit.

The hill is now listed with a 66m summit and 32m bwlch height, with both spot heights taken from the Ordnance Survey enlarged mapping hosted on the Geograph website.  These values give the hill 34m of drop and 51.52% Dominance.


The full details for the hill are:

Group:  Pen Llŷn

Name:  Pt. 66m

Dominance:  51.52%

OS 1:50,000 map:  123

Summit Grid Reference:  SH 29957 27041

Summit Height:  66m

Drop Summit to Bwlch:  34m

Drop Bwlch to ODN:  32m 


Myrddyn Phillips (March 2017)






Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Carreg Rhoson (SM 672 256) - Dominant addition (13th reclassification)


There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales due to detail included on the Ordnance Survey enlarged mapping hosted on the Geograph website.  This has resulted in the hill being added to the Dominant list.  With the criteria for inclusion to this list being those Welsh P30 hills whose prominence equal or exceed half that of their absolute height.

The details relating to this hill’s inclusion as a Dominant hill are retrospective as it was added to the list shortly after its initial compilation was completed with the date of 31st October 2012 given against its details.

Prior to this hill being listed as a P30 and its inclusion as a Dominant hill it had remained unclassified, as the uppermost 30m ring contour on the Ordnance Survey 1:25,000 Explorer map had not been spotted.

The hill is in the Pembrokeshire Islands group of hills and is placed in the Region of Mid and West Wales (Region B, Sub-Region B4) and is situated 5.175km from the nearest paved public road off the Pembrokeshire coast, and is positioned in the island chain of the Bishops and Clerks.

The name of the hill is Carreg Rhoson and this is also the name given to a number of adjacent islets, it is included as a Dominant hill as the Ordnance Survey enlarged mapping hosted on the Geograph website has greater scale and definition when compared to the smaller scaled and publicly available Ordnance Survey maps, and therefore its uppermost 30m ring contour is easier to see, and as this hill is also an island its c 30m summit height also gives it 100.00% Dominance.


The full details for the hill are:

Group:  Pembrokeshire Islands

Name:  Carreg Rhoson

Dominance:  100.00%

OS 1:50,000 map:  157

Summit Grid Reference:  SM 67235 25678

Summit Height:  c 30m

Drop Summit to Bwlch:  N/A

Drop Bwlch to ODN:  N/A 


The island chain of Carreg Rhoson with the new Dominant hill (SM 672 256) being the highest point on the right of this photograph

Myrddyn Phillips (March 2017)






Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Castell Cricieth (SH 500 377) - Dominant addition (12th reclassification)

Survey post for Castell Cricieth


There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales due to detail included on the Ordnance Survey enlarged mapping hosted on the Geograph website and which was first spotted by Alex Cameron.  This has resulted in the hill being added to the Dominant list.  With the criteria for inclusion to this list being those Welsh P30 hills whose prominence equal or exceed half that of their absolute height.

The details relating to this hill’s inclusion as a Dominant hill are retrospective as it was added to the list shortly after Alex first proposed it as a new P30 in September 2014, and later appeared in the Moel Hebog group of hills when published on Mapping Mountains on the 28th January 2016.

Prior to Alex Cameron proposing this hill as a new P30 and its subsequent inclusion as a Dominant hill it had remained unclassified, as the Ordnance Survey 1:50,000 Landranger map and 1:25,000 Explorer map has an uppermost contour of 30m and bwlch contouring between 10m – 20m, which implied that this hill did not have the required 30m of drop to be considered for Dominant status.

The hill is in the Moel Hebog group of hills and is placed in the Region of North Wales (Region A, Sub-Region A1) and is situated in the heartland of the town of Cricieth overlooking the sea, which is to its immediate east and south.

The name of the hill is taken from the castle at its top; Castell Cricieth,  and there is an admittance fee for those wishing to visit, it was included as a Dominant hill as the Ordnance Survey enlarged map hosted on the Geograph website has contours at 5m intervals giving the hill an uppermost contour of 45m and a summit spot height of 48m, with bwlch contouring between 15m – 20m, with an estimated bwlch of c 18m, giving the hill an estimated drop of c 30m and 62.5% Dominance.  The hill has subsequently been surveyed with the Trimble GeoXH 6000 with a summit height of 49.6m (converted to OSGM15) and a bwlch height of 19.3m (converted to OSGM15), with these values giving the hill 30.3m of drop and 61.02% Dominance.


The full details for the hill are:

Group:  Moel Hebog

Name:  Castell Cricieth

Dominance:  61.02%

OS 1:50,000 map:  123

Summit Grid Reference:  SH 50003 37733

Summit Height:  49.6m (converted to OSGM15)

Drop Summit to Bwlch:  30.3m

Drop Bwlch to ODN:  19.3m (converted to OSGM15) 


Castell Cricieth (SH 500 377) confirmed as a Dominant hill


Myrddyn Phillips (March 2017)







Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Ynys Hir (SH 566 396) - Dominant addition (11th reclassification)

Survey post for Ynys Hir

Significant Height Revisions post for Ynys Hir


There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales due to a survey with the Trimble GeoXH 6000.  This has resulted in the hill being added to the Dominant list.  With the criteria for inclusion to this list being those Welsh P30 hills whose prominence equal or exceed half that of their absolute height.

The details relating to this hill’s inclusion as a Dominant hill are retrospective as it was surveyed on the 1st February 2014 and later appeared in the Moel Hebog group of Dominant hills when published on the Mappingn Mountains site on the 28th January 2016.

Prior to the survey with the Trimble this hill was unclassified as the Ordnance Survey 1:50,000 Landranger map, 1:25,000 Explorer map and the enlarged mapping hosted on the Geograph website all give the hill an uppermost 20m ring contour, implying that its height is not sufficient for P30 status and consideration as a Dominant hill.  However, it was Aled Williams who first proposed that this hill may attain P30 status and it was subsequently surveyed in his company.

The hill is in the Moel Hebog group of hills and is placed in the Region of North Wales (Region A, Sub-Region A1) and is situated between the communities of Porthmadog to its south and Tremadog to its north north-west, with the A 487 road to its immediate south.  The hill can be visited from this road where a lay-by gives access through a gate into the woodland that covers this and the other adjacent small hills.

The name of the hill is Ynys Hir and as its name implies it forms an island, which is now landlocked, it is included as a Dominant hill as the survey with the Trimble GeoXH 6000 produced a summit height of 37.3m, and with an estimated bwlch height of c 3m it gives this hill 91.21% Dominance.


The full details for the hill are:

Group:  Moel Hebog

Name:  Ynys Hir

Dominance:  91.21%

OS 1:50,000 map:  124

Summit Grid Reference:  SH 56695 39693

Summit Height:  37.3m (converted to OSGM15)

Drop Summit to Bwlch:  c 34m

Drop Bwlch to ODN:  c 3m 


Beyond the cliffs and immersed in woodland is the summit of Ynys Hir (SH 566 396) which is now classified as a Dominant hill


Myrddyn Phillips (February 2017)






Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Dinas Dinlle (SH 436 564) - Dominant addition (10th reclassification)

Survey post for Dinas Dinlle


There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales due to detail included on the Ordnance Survey enlarged mapping hosted on the Geograph website and which was first spotted by Chris Watson, and subsequently confirmed via a survey with the Trimble GeoXH 6000.  This has resulted in the hill being added to the Dominant list.  With the criteria for inclusion to this list being those Welsh P30 hills whose prominence equal or exceed half that of their absolute height.

The details relating to this hill’s inclusion as a Dominant hill are retrospective as it was added to the list shortly after its initial compilation and later appeared in the Moel Hebog group of hills when published on Mapping Mountains on the 28th January 2016.

Prior to Chris Watson raising the probability of this hill being a P30 and its subsequent inclusion as a Dominant hill it had remained unclassified, as the Ordnance Survey 1:50,000 Landranger map gave a 31m summit spot height and bwlch contouring between 0m – 10m, whilst the 1:25,000 Explorer map gave an uppermost 30m ring contour and the same bwlch contouring, which implied that the hill did not have the required 30m of drop to be considered for Dominant status.

The hill is positioned in the Moel Hebog group of hills and is placed in the Region of North Wales (Region A, Sub-Region A1) and is situated on the outskirts of the small community that takes its name from the hill; Dinas Dinlle, and is positioned with the sea to its immediate west which has eroded much of its slopes over recent years.  If wanting to visit the hill it can be easily accessed from the car park adjacent to the sea front from where a path heads up its northern slopes.

The name of the hill is Dinas Dinlle and as its name implies the upper section of the hill comprises an ancient hill fort, it was included as a Dominant hill as the Ordnance Survey enlarged mapping hosted on the Geograph website has contours at 5m intervals giving the hill an uppermost contour of 35m and bwlch contouring between 0m – 5m, these values gave the hill an estimated drop of c 31m – c 32m.  The summit of the hill has subsequently been surveyed with the Trimble GeoXH 6000 as being 34.7m (converted to OSGM15) high and with an estimated bwlch height of c 3m this gives the hill 92.16% Dominance.


The full details for the hill are:

Group:  Moel Hebog

Name:  Dinas Dinlle

Dominance:  92.16%

OS 1:50,000 map:  115, 123

Summit Grid Reference:  SH 43676 56438

Summit Height:  34.7m (converted to OSGM15)

Drop Summit to Bwlch:  c 32m

Drop Bwlch to ODN:  c 3m


Dinas Dinlle (SH 436 564) now classified as a Dominant hill


Myrddyn Phillips (February 2017)






Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Geirth Mawr (SH 535 393) - Dominant deletion (9th reclassification)


There has been a deletion to the listing of Y Trechol – The Dominant Hills of Wales due to detail included on the Ordnance Survey enlarged mapping hosted on the Geograph website.  This has resulted in the hill being taken out of the Dominant list.  With the criteria for inclusion to this list being those Welsh P30 hills whose prominence equal or exceed half that of their absolute height.

The details relating to this hill’s deletion as a Dominant hill are retrospective as it did not appear in the Moel Hebog group of hills when published on Mapping Mountains on the 28th January 2016.

The hill had been listed in the ‘Hills to be surveyed’ sub-list that accompanied the original Welsh P30 lists when published on Geoff Crowder’s v-g.me website, however when drop values were added to the hand written Master List this hill’s details were re-evaluated and it was catalogued with c 30m of drop based on a summit height of c 58m and a bwlch height of 28m, these values were sufficient for it to be included in the original listing of Y Trechol – The Dominant Hills of Wales with 30m of drop and 51.72% Dominance.

The hill is in the Moel Hebog group of hills and is placed in the Region of North Wales (Region A, Sub-Region A1) and is situated between the small communities of Pentrefelin to its west north-west and Penmorfa to its north-east, with the town of Porthmadog situated to its east.

The hill can be relatively easily accessed from its north-west starting from the A 497 as it makes its way from Porthmadog to Cricieth, the ascent is through deciduous woodland but is not on open access land so permission to visit should be sought.

The name of the hill is Geirth Mawr and it has been deleted from the Dominant list as the Ordnance Survey enlarged mapping hosted on the Geograph website gives the hill a summit spot height of 56m and with a 28m spot height appearing on the area of the connecting bwlch on Ordnance Survey 1:25,000 Explorer maps, it gives this hill 28m of drop, which is insufficient for it to qualify as a Dominant hill.


The full details for the hill are:

Group:  Moel Hebog

Name:  Geirth Mawr

Dominance:  N/A

OS 1:50,000 map:  124

Summit Grid Reference:  SH 53512 39361

Summit Height:  56m

Drop Summit to Bwlch:  28m

Drop Bwlch to ODN:  28m


Myrddyn Phillips (February 2017)






Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Bodlondeb Wood (SH 779 781) - Dominant addition (8th reclassification)


There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales due to detail included on the Ordnance Survey enlarged mapping hosted on the Geograph website.  This has resulted in the hill being added to the Dominant list.  With the criteria for inclusion to this list being those Welsh P30 hills whose prominence equal or exceed half that of their absolute height.

The details relating to this hill’s inclusion as a Dominant hill are retrospective as it appeared in the Carneddau group of hills when published on Mapping Mountains on the 17th December 2015.

Prior to this hill’s inclusion as a Dominant hill it had remained unclassified outside of its recent inclusion as a Tump, as Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map detail only gave the hill an uppermost 50m ring contour and bwlch contouring between 20m – 30m, with a drop of c 27m based on an estimated summit height of c 53m and an estimated bwlch height of c 26m.

The hill is in the Carneddau group of hills and is placed in the Region of North Wales (Region A, Sub-Region A1) and is situated on the outskirts of Conwy with the Afon Conwy to its immediate north and east.

If wanting to visit the hill it can be accessed relatively easily with public parking available next to where the Offices are marked to the south of the summit on Ordnance Survey maps.  There are a number of paths marked on the map that head up to, or contour around the summit, and as the name of the hill suggests it is part of a wood which consists of deciduous trees.

The name of the hill is Bodlondeb Wood and it is included as a Dominant hill as the Ordnance Survey enlarged map hosted on the Geograph website has contours at 5m intervals giving the hill an uppermost contour of 55m and bwlch contouring between 20m – 25m.  Therefore the summit is estimated as being c 57m high and the bwlch estimated as being c 23m high, with these values giving this hill c 34m of drop and 59.65% Dominance.


The full details for the hill are:

Group:  Carneddau

Name:  Bodlondeb Wood

Dominance:  59.65%

OS 1:50,000 map:  115

Summit Grid Reference:  SH 77923 78114

Summit Height:  c 57m

Drop Summit to Bwlch:  c 34m

Drop Bwlch to ODN:  c 23m 


Myrddyn Phillips (February 2017)






Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Mynydd Coch (SH 804 099) - Lesser Dominant deletion (7th reclassification)

Survey post for Mynydd Coch

Significant Name Changes post for Mynydd Coch


There has been a deletion from the listing of Y Trechol – The Dominant Hills of Wales due to a survey with the Trimble GeoXH 6000 and which has resulted in the hill being taken out of The Lesser Dominant Hills of Wales list and subjected to a life of rather pitiful non dominance.  The hill is in the group known as Bryniau Dyfi and is situated between the small communities of Aberllefenni to the west and Aberangell to the east, with the expanse of the Dyfi Forest enclosing the hill on its north, east and south.

The Trimble GeoXH 6000 survey that resulted in this hill’s deletion was conducted on the 13th May 2015 in the company of Graham Jackson on a fine late spring day in clear and sunny conditions.

If wanting to visit the hill it can be accessed relatively quickly from its north-east where a forest track leaves the minor road that crosses these hills and makes its way toward the eastern face of Mynydd Coch and open countryside.  However, a more rewarding and extended walk starts from Aberllefenni with the path making its way to the summit through a deciduous wood and toward the 400m Sub-Pedwar of Foel Lwyd before the final ascent of the hill’s southerly upper slopes.

The name of the hill is Mynydd Coch and it had been listed with 33.48% Dominance which was based on its summit spot height of 469m and a bwlch spot height of 312m, with these values giving the hill 157m of drop.  The result of the Trimble GeoXH 6000 summit survey is 468.3m (468.298m, converted to OSGM15) and when coupled with this hill’s 312m map heighted bwlch gives this hill 156m of drop and only 33.31% Dominance, a smidgeon under the minimum qualifying percentage for Lesser Dominance.


The full details for the hill are:

Group:  Bryniau Dyfi

Name:  Mynydd Coch

Dominance:  33.31%

OS 1:50,000 map:  124, 125

Summit Grid Reference:  SH 80458 09952

Summit Height:  468.3m (converted to OSGM15)

Drop Summit to Bwlch:  156m

Drop Bwlch to ODN:  312m 


Mynydd Coch (SH 804 099) now deleted from the Lesser Welsh Dominants list

For details on the survey that resulted in this hill being demoted from the Lesser Welsh Dominant list please click {here}

Myrddyn Phillips (October 2016)






Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Foel Fawr (SM 705 225) - Lesser Dominant addition (6th reclassification)

Survey post for Foel Fawr


There has been a new entry in to the ranks of Y Trechol – The Dominant Hills of Wales due to a survey with the Trimble GeoXH 6000 and which has resulted in the hill being listed in The Lesser Dominant Hills of Wales list.  The hill is in the group known as the Pembrokeshire Islands and is situated on the southern part of Ynys Dewi, which is also commonly known as Ramsey.  This island is situated to the west of St David’s in the south-west of Wales.

The Trimble GeoXH 6000 survey that resulted in this hill’s reclassification was conducted on the 15th May 2016 on a beautiful afternoon in still and sunny conditions.

As the hill is situated on an island the only way to approach is via boat and the only company with permission to land on Ynys Dewi is Thousand Island Adventures (tel: 01437-721721).  The hill can be easily accessed from where the boat docks as a gravelled track leads up to The Farmhouse from where a good path heads toward the southern part of the island.

The name of the hill is Foel Fawr and until the survey with the Trimble GeoXH 6000 the hill was listed with c 29m of drop, based on the 72m summit spot height on current Ordnance Survey maps, and an estimated bwlch height of c 43m based on bwlch contouring between 40m – 45m, with these values giving the hill c 29m of drop which is insufficient for qualification to the Y Trechol – The Dominant Hills of Wales list.

The survey with the Trimble GeoXH 6000 resulted in a 72.0m (71.954m, converted to OSGM15) summit height and a 41.9m (41.899m, converted to OSGM15)) bwlch height, with these values giving the hill 30.1m of drop and a Dominance of 41.77% which is sufficient for it to qualify as a Lesser Welsh Dominant hill.


The full details for the hill are:

Group:  Pembrokeshire Islands

Name:  Foel Fawr

Dominance:  41.77%

OS 1:50,000 map:  157

Summit Grid Reference:  SM 70542 22567

Summit Height:  72.0m (converted to OSGM15)

Drop Summit to Bwlch:  30.1m

Drop Bwlch to ODN:  41.9m (converted to OSGM15)  



Foel Fawr (SM 705 225) now classified as a Lesser Welsh Dominant


Myrddyn Phillips (May 2016)







Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Carn Ysgubor (SM 699 246) - Lesser Dominant reclassified to Dominant (5th reclassification)

Survey post for Carn Ysgubor


Please note; since this Hill Reclassifications post was announced the Ordnance Survey have adopted OSGM15, this remodelling has altered the known accurate height of Welsh hills be approximately 2-4cm, and the conversion to OSGM15 of data produced by the Trimble for Carn Ysgubor has resulted in this hill being reclassified back to the ranks of Lesser Dominant hills.


There has been a reclassification from the listing of Y Trechol – The Dominant Hills of Wales due to a survey with the Trimble GeoXH 6000 and which has resulted in the hill being taken out of The Lesser Welsh Dominant list and included in the Dominant list.  The hill is in the Group known as the Pembrokeshire Islands and is situated on the northern part of Ynys Dewi, which is also commonly known as Ramsey.  This island is situated to the west of St David’s in the south-west of Wales.

The Trimble GeoXH 6000 survey that resulted in this hill’s reclassification was conducted on the 15th May 2016 on a beautiful morning in still and sunny conditions.

As the hill is situated on an island the only way to approach is via boat and the only company with permission to land on Ynys Dewi is Thousand Island Adventures (tel: 01437-721721).  The hill can be easily accessed from where the boat docks as a gravelled track leads up to The Farmhouse from where a vehicle path heads toward The Bungalow, which is a house on the eastern slopes of the hill.  A narrower path leaves this main route and heads toward the summit of the hill.

The name of the hill is Carn Ysgubor, with its composition presented as Carnysgubor on current Ordnance Survey maps, and it had been listed with 49.50% Dominance based on the 101m summit spot height on Ordnance Survey maps and an estimated bwlch height of c 51m, these values gave this hill c 50m of drop. 

The survey with the Trimble GeoXH 6000 resulted in a 102.4m (102.369m) summit height and a 51.2m (51.182m) bwlch height, giving this hill a Dominance of 50.00% (50.002442%) and therefore it just sneaks in to the ranks of being classified as a Dominant hill and confirms its reclassification from a Lesser Welsh Dominant to the ranks of Y Trechol - The Dominant Hills of Wales.


The full details for the hill are:

Group:  Pembrokeshire Islands

Name:  Carn Ysgubor

Dominance:  50.00%

OS 1:50,000 map:  157

Summit Grid Reference:  SM 69953 24603

Summit Height:  102.4m

Drop Summit to Bwlch:  51.2m

Drop Bwlch to ODN:  51.2m 



Carn Ysgubor (SM 699 246) now reclassified from a Lesser Welsh Dominant to a Dominant hill


Myrddyn Phillips (May 2016)







Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Ynys Fach (SM 822 327) - Dominant deletion (4th reclassification)

Survey post for Ynys Fach


There has been a deletion from the listing of Y Trechol – The Dominant Hills of Wales due to a survey with the Trimble GeoXH 6000 and which has resulted in the hill being taken out of the main Dominant list and subjected to a life of rather pitiful non dominance.  The hill is in the group known as the Pembrokeshire Islands and is situated on the northern coast of Pembrokeshire, and is positioned between the small communities of Trefin (Trevine) to its east and Porthgain to its west.

The hill is better described as an island, and even more so as a tidal island, as it is connected to the coastline of mainland Wales by a pebbled beach that according to maps is cut off from the mainland at high water.  It can be approached by boat, but an ascent of the island is feasible, albeit with a steep and potentially dangerous descent to the bwlch from the mainland.  This approach starts from directly opposite the island and necessitates finding a route down through scrub undergrowth and bi-passing the rock and cliffs that predominate this part of the coastline.  If attempting this route please be careful.

The Trimble GeoXH 6000 survey that resulted in this island’s deletion was conducted on the 14th May 2016 on a beautiful sunny evening in the company of Adrian Rayner, Ayako and Rob Woodall.  It was Rob’s suggestion to go and have a look at it, and he found the route down to the pebbled beach which constitutes this island’s connecting bwlch.

The name of the island is Ynys Fach and it had been listed with 96.77% Dominance based on a summit height of c 31m estimated from the island having an uppermost 30m ring contour on current Ordnance Survey maps, and an estimated bwlch height of 1m taken to the pebbled beach connecting this island to the mainland.

Two points were surveyed for summit position and these are given below:


Summit 1:  30.8m (30.789m, converted to OSGM15) at SM 82209 32743

Summit 2:  30.7m (30.727m, converted to OSGM15) at SM 82217 32752


The data set for the bwlch was remarkably good when considering that the equipment was placed in what resembled an enclosed and walled canyon, with the resulting height being 1.2m (1.225m, converted to OSGM15) at SM 82180 32693.  These values give Ynys Fach a drop of only 29.6m which is below the minimum of 30m drop required for qualification to the Y Trechol – the Dominant Hills of Wales list.


The full details for the hill are:

Group:  Pembrokeshire Islands

Name:  Ynys Fach

Dominance:  N/A

OS 1:50,000 map:  157

Summit Grid Reference:  SM 82209 32743

Summit Height:  30.8m (converted to OSGM15)

Drop Summit to Bwlch:  29.6m

Drop Bwlch to ODN:  1.2m (converted to OSGM15)  



Ynys Fach (SM 822 327) now deleted from the ranks of Y Trechol - The Dominant Hills of Wales


Myrddyn Phillips (May 2016)







Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Moel y Gadair (SH 521 391) - Lesser Dominant deletion (3rd reclassification)

Summit survey post for Moel y Gadair

Bwlch survey post for Moel y Gadair


There has been a deletion from the listing of Y Trechol – The Dominant Hills of Wales due to a survey with the Trimble GeoXH 6000 and which has resulted in the hill being taken out of The Lesser Welsh Dominant list and subjected to a life of rather pitiful non dominance.

The hill is in positioned in the Moel Hebog group and is situated on the south-western outskirts of the small community of Pentrefelin, which is positioned between the towns of Porthmadog to its east and Cricieth to its south-west.

The Trimble GeoXH 6000 survey that resulted in this hill’s deletion was conducted over two days, with the hill’s summit being surveyed on the 15th June 2015 in warm and sunny conditions, and the bwlch being surveyed on the 23rd February 2016 on a beautiful winter’s day.

If wanting to visit the hill it can be accessed from a public footpath to its south-west, but as its summit is not on open access land permission to visit its high point should be sought.

The name of the hill is Moel y Gadair and it had been listed with 45.05% Dominance and a drop value of c 30m, with the latter figure the minimum required for qualification to the Dominance list.  These figures were based on a summit survey of 66.7m (converted to OSGM15) and an interpolated bwlch height of c 37m based on bwlch contouring between 35m – 40m.  During the 15th June 2015 survey the contours at the bwlch had been misinterpreted resulting in the second bwlch survey which was conducted on the 23rd February 2016 and which resulted in a bwlch height of 38.1m (converted to OSGM15).

The survey with the Trimble GeoXH 6000 resulted in a 66.7m (converted to OSGM15) summit height and a 38.1m (converted to OSGM15) bwlch height, giving this hill a drop of only 28.5m which is insufficient for qualification to the Dominant list.


The full details for the hill are:

Group:  Moel Hebog

Name:  Moel y Gadair

Dominance:  N/A

OS 1:50,000 map:  124

Summit Grid Reference:  SH 52165 39135

Summit Height:  66.7m (converted to OSGM15)

Drop Summit to Bwlch:  28.5m

Drop Bwlch to ODN:  38.1m (converted to OGM15)  


The final nail in the coffin - gathering data at the critical bwlch of Moel y Gadair (SH 521 391)  which resulted in this hill's deletion from the Lesser Welsh Dominant list

For details on the survey that resulted in this hill being demoted from The Lesser Welsh Dominant list please click {here} for summit and {here} for the bwlch survey.


Myrddyn Phillips (February 2016)






Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Moelfre (SH 558 375) - Dominant reclassified to Lesser Dominant (2nd reclassification)

Survey post for Moelfre

Significant Name Changes post for Moelfre


There has been a reclassification from the listing of Y Trechol – The Dominant Hills of Wales due to a survey with the Trimble GeoXH 6000 and which has resulted in the hill being taken out of the Dominant list and included in the Lesser Welsh Dominant list.  The hill is in the Group known as Moel Hebog and is situated to the south-west of Porthmadog, overlooking the coast and above the small community of Borth-y-gest.

The Trimble GeoXH 6000 survey that resulted in this hill’s reclassification was conducted on the 23rd February 2016 on a beautiful winter’s morning in sunny conditions.

The hill can be accessed from its west, east, south and north, with my two visits starting from the south and north respectively.  Access to mid-way up the hill can be gained via public footpaths but the high point is not on open access land, so permission to visit should be sought.

The hill remains unnamed on current Ordnance Survey maps but local enquiry with Aled Williams; a native of Porthmadog, confirms that the hill is known locally as Moelfre.

The hill had been listed with 50.00% of Dominance and was therefore included in the main Dominant list.  This was based on it having a 74m summit spot height on the Ordnance Survey enlarged mapping hosted on the Geograph website and an estimated bwlch height of c 37m based on bwlch contouring between 35m – 40m, these values gave the hill a prominence of c 37m, which was enough for it to sneak into the main Dominant list.

The survey with the Trimble GeoXH 6000 resulted in a 74.1m (74.056m, converted to OSGM15) summit height and a 37.8m (37.770m, converted to OSGM15) bwlch height, giving this hill a Dominance of only 49.00% and confirming its reclassification from The Dominant Hills of Wales list to The Lesser Welsh Dominant list.


The full details for the hill are:

Group:  Moel Hebog

Name:  Moelfre

Dominance:  49.00%

OS 1:50,000 map:  124

Summit Grid Reference:  SH 55830 37553

Summit Height:  74.1m (converted to OSGM15)

Drop Summit to Bwlch:  36.3m

Drop Bwlch to ODN:  37.8m (converted to OSGM15)  


Moelfre (SH 558 375) now reclassified to the Lesser Welsh Dominant list

For details on the survey that resulted in this hill being reclassified to a Lesser Welsh Dominant hill please click {here}

Myrddyn Phillips (February 2016)







Mapping Mountains - Hill Reclassifications - Y Trechol - The Dominant Hills of Wales

Pt. 68.2m (SH 383 949) - Dominant reclassified to Lesser Dominant (1st reclassification)

Survey post for Pt. 68.2m


There has been a reclassification from the listing of Y Trechol – The Dominant Hills of Wales due to a survey with the Trimble GeoXH 6000 and which has resulted in the hill being taken out of the Dominant list and included in The Lesser Welsh Dominant list.  The hill is in the first Group to be published in this new hill list; Ynys Môn, and is situated on the northern coast of the island and positioned to the north-east of the small community of Cemaes.

This Hill Reclassifications notification has awaited the listing of Y Trechol – the Dominant Hills of Wales to begin its publication, but the survey result is retrospective as the Trimble GeoXH 6000 survey that resulted in this hill’s reclassification was conducted on the 7th September 2014 on a beautiful sunny day in the company of Alex Cameron.

The hill can be accessed from its west or east via the Wales Coast Path which goes close to its summit, with its eastern approach on this path being joined by a public footpath that gives access toward the hill from its south-east.  However, if wanting a slightly extended walk this hill can be combined with its neighbours of Dinas Gynfor (SH 391 950) and Graig Wen (SH 397 947).

The hill is unnamed on current Ordnance Survey maps and I do not know a locally known name for it or one of historical relevance and therefore the point (Pt. 68.2m) notation is being used for the hill.
The hill had been listed with 50.75% of Dominance and was therefore included in the main Dominant list.  This was based on it having a 67m summit spot height on the Ordnance Survey enlarged mapping hosted on the Geograph website and an estimated bwlch height of c 33m based on bwlch contouring between 30m – 35m, these values gave the hill a prominence of c 34m, which was enough for it to sneak into the main Dominant list.

The survey with the Trimble GeoXH 6000 resulted in a 68.2m (converted to OSGM15) summit height and a 34.2m (converted to OSGM15) bwlch height, giving this hill a Dominance of only 49.85% and confirming its reclassification from The Dominant Hills of Wales list to The Lesser Welsh Dominant list.


The full details for the hill are:

Group:  Ynys Mon

Name:  Pt. 68.2m

Dominance:  49.85% (Lesser Welsh Dominant status confirmed)

OS 1:50,000 map:  114

Summit Grid Reference:  SH 38337 94993

Summit Height:  68.2m (converted to OSGM15)

Drop Summit to Bwlch:  34.0m

Drop Bwlch to ODN:  34.2m (converted to OSGM15)  


Pt. 68.2m (SH 383 949) now reclassified to the Lesser Welsh Dominant list.

For details on the survey that resulted in this hill being reclassified to a Lesser Welsh Dominant hill please click {here}

Myrddyn Phillips (December 2015)












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